BỘ GIAO THÔNG VẬN
TẢI
CỤC HÀNG KHÔNG VIỆT NAM
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CỘNG HÒA XÃ HỘI CHỦ
NGHĨA VIỆT NAM
Độc lập - Tự do - Hạnh phúc
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Số: 1045/QĐ-CHK
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Hà Nội, ngày 10
tháng 5 năm 2024
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QUYẾT
ĐỊNH
VỀ VIỆC BAN HÀNH HƯỚNG DẪN VIỆC THỰC HIỆN QUY
ĐỊNH, KHUYẾN CÁO THỰC HÀNH CỦA ICAO (DOC 9157 - PART 2) VỀ ĐƯỜNG LĂN, SÂN ĐỖ
TÀU BAY VÀ SÂN CHỜ TẠI SÂN BAY
CỤC
TRƯỞNG CỤC HÀNG KHÔNG VIỆT NAM
Căn cứ Luật Hàng không
dân dụng Việt Nam ngày 29/6/2006 và Luật sửa đổi, bổ sung một số điều của Luật Hàng
không dân dụng Việt Nam ngày 21/11/2014;
Căn cứ Nghị định số
66/2015/NĐ-CP ngày 12/8/2015 của Chính phủ quy định về Nhà chức trách hàng
không;
Căn cứ Nghị định số
05/2021/NĐ-CP ngày 25/01/2021 của Chính phủ về quản lý, khai thác cảng hàng không,
sân bay, Nghị định số 20/2024/NĐ-CP ngày 23/02/2024 sửa đổi Nghị định số 05/2021/NĐ-CP ;
Căn cứ Nghị định số
64/2022/NĐ-CP ngày 15/9/2022 của Chính phủ về sửa đổi, bổ sung một số điều của
các Nghị định liên quan đến hoạt động kinh doanh trong lĩnh vực hàng không dân
dụng;
Căn cứ Thông tư số 29/2021/TT-BGTVT
ngày 30/11/2021 của Bộ Giao thông vận tải quy định chi tiết về quản lý, khai
thác cảng hàng không, sân bay;
Căn cứ Thông tư số 19/2017/TT-BGTVT
ngày 06/6/2017 của Bộ Giao thông vận tải về quản lý, bảo đảm hoạt động bay, Thông
tư số 32/2021/TT- BGTVT ngày 14/12/2021 của Bộ Giao thông vận tải sửa đổi Thông
tư số 19/2017/TT-BGTVT ;
Căn cứ Quyết định số
651/QĐ-BGTVT ngày 29/5/2023 của Bộ trưởng Bộ Giao thông vận tải quy định chức
năng, nhiệm vụ, quyền hạn và cơ cấu tổ chức của Cục Hàng không Việt Nam; Quyết
định số 371/QĐ-BGTVT ngày 02/4/2024 của Bộ trưởng Bộ Giao thông vận tải về việc
sửa đổi Điều 3 Quyết định số 651/QĐ-BGTVT;
Xét đề nghị của Trưởng
phòng Quản lý cảng hàng không, sân bay.
QUYẾT
ĐỊNH:
Điều 1. Ban
hành kèm theo Quyết định này Hướng dẫn việc thực hiện quy định, khuyến cáo thực
hành của ICAO (Doc 9157 - Part 2) về Đường lăn, sân đỗ tàu bay và sân chờ tại
sân bay (Số tham chiếu: GM 2.2).
Điều 2. Quyết
định này có hiệu lực kể từ ngày ký.
Điều 3. Các
ông/bà Tổng giám đốc Tổng công ty Cảng hàng không Việt Nam - CTCP, Tổng giám
đốc Tổng công ty Quản lý bay Việt Nam, Tổng giám đốc Cảng hàng không quốc tế
Vân Đồn, Giám đốc các Cảng vụ hàng không miền Bắc, miền Trung, miền Nam, Trưởng
phòng Quản lý cảng hàng không, sân bay và Thủ trưởng các cơ quan, đơn vị liên
quan chịu trách nhiệm thi hành Quyết định này./.
Nơi nhận:
-
Như Điều 3;
- Cục trưởng (để b/c);
- Các Phó Cục trưởng;
- Các phòng: QLC, QLHĐB, TCATB, ANHK, KHCNMT, PC-HTQT, TTHK;
- Lưu: VT, QLC (TD 10bn).
|
KT. CỤC TRƯỞNG
PHÓ CỤC TRƯỞNG
Phạm Văn Hảo
|
AERODROME
DESIGN MANUAL
Taxiways,
Aprons and Holding Bays
Hướng dẫn việc thực hiện quy định, khuyến cáo
thực hành của ICAO (Doc 9157 - Part 2) về Đường lăn, sân đỗ tàu bay và sân chờ
tại sân bay
(GM 2.2)
Issued
herewith Decision No. 1045/QD-CHK dated 10th May 2024
VERSION
RECORDS
Date
of issue
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Subject(s)/
Amendment
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Source
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Effective
date
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Note
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10th
May 2024
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First
Edition
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ICAO
Doc 9157 - Part 2 (2020)
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10th
May 2024
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TABLE
OF CONTENTS
FOREWORD
1. BACKGROUND
2. SCOPE AND PURPOSE
CHAPTER 1
TAXIWAYS
1.1 TAXIWAY SYSTEMS
1.2 PHYSICAL
CHARACTERISTICS DESIGN CRITERIA
1.3 RAPID EXIT
TAXIWAYS (RETS)
1.4 TAXIWAYS ON
BRIDGES
1.5 FILLETS
1.6 TAXIWAY SHOULDERS
AND STRIPS
1.7 FUTURE AIRCRAFT
DEVELOPMENTS
CHAPTER 2
HOLDING BAYS AND
OTHER BYPASSES
2.1 NEED FOR HOLDING
BAYS AND OTHER BYPASSES
2.2 TYPES OF BYPASSES
2.3 COMMON DESIGN
REQUIREMENTS AND CHARACTERISTICS
2.4 SIZE AND LOCATION
OF HOLDING BAYS
2.5 HOLDING BAY
MARKING AND LIGHTING
CHAPTER 3
APRONS
3.1 TYPES OF APRONS
3.2 DESIGN
REQUIREMENTS
3.3 BASIC TERMINAL
APRON LAYOUTS
3.4 SIZE OF APRONS
3.5 APRON GUIDANCE
3.6 DE-ICING/ANTI-ICING
FACILITIES
CHAPTER 4
SEGREGATION OF
TRAFFIC ON THE MOVEMENT AREA
4.1 NEED FOR TRAFFIC
SEGREGATION
4.2 ACTIVITIES
CAUSING A MIX OF AIRCRAFT AND GROUND VEHICLES
4.3 METHODS TO
ACHIEVE SEGREGATION
APPENDIX 1
FILLET DESIGN
APPENDIX 2
JET BLAST AND BLAST
FENCE CONSIDERATIONS
APPENDIX 3
AEROPLANE
CLASSIFICATION BY CODE NUMBER AND LETTER
APPENDIX 4
TAXIWAY DEVIATION
STUDIES
APPENDIX 5
DESIGN, LOCATION AND
NUMBER OF RAPID EXIT TAXIWAYS
FOREWORD
1. BACKGROUND
1.1 Pursuant to Article
11, Clause 2 of the Decree No. 66/2015/ND-CP dated 12th August 2015 on the
Civil Aviation Authority stipulating the function and responsibility of the
Civil Aviation Authority of Viet Nam (CAAV) in guiding the implementation of
Standards and Recommended Practices of ICAO.
1.2 Pursuant to Article
8, Clause 10 of the Decree No. 05/2021/ND-CP dated 25th January 2021 on the management
and operation of airport and aerodrome stipulating the function and responsibility
in providing guidance on and issue professional instructions related to
management and operation of airports/aerodromes in line with regulations of law
and regulations of ICAO (including: documents providing guidelines for
airport/aerodrome design; documents providing guidelines for operation and
assurance of security and safety at airports/aerodromes).
1.3 Pursuant to Article
4, Clause 6 of the Decree No. 0/5/2021/ND-CP dated 25th January 2021 stipulating
details of airport/aerodrome infrastructure shall be designed and operated
according to the standards of International Civil Aviation Organization (ICAO).
1.4 This Manual is
issued by CAAV specifying the details of provisions to be met by the AO organizations,
originators related. The details in this Manual are based on those stipulated
in ICAO Doc 9157 - Part 2 [as in force and amended from time to time by the
Council of the International Civil Aviation Organization (ICAO)] and with such
modifications as may be determined by CAAV to be applicable in Viet Nam.
1.5 Amendments to
this document are the responsibility of the Airport Management Department -
CAAV. Readers should forward advice of errors, inconsistencies or suggestions
for improvement to this Manual to the addressee stipulated below.
Airport Management
Department - CAAV
No. 119, Nguyen Son
Street, Gia Thuy ward, Long Bien district, Ha Noi. Email Address:
and@caa.gov.vn.
2.
SCOPE AND PURPOSE
2.1 This Manual
includes guidance on the general layout and description of updated design
criteria for taxiway physical characteristics, including the shoulder and
strips. The guidance is based on well-equipped modern aircraft which have
increased capabilities offered by advanced technologies, often providing very
precise guidance on landing, take-off and taxiing.
In accordance with the
provisions in Annex 14 - Aerodromes, Volume I - Aerodrome Design and Operations,
it is recommended to provide holding bays when the traffic volume is high and
the provision of aprons where necessary, to permit the on- and off- loading of
passengers, cargo or mail as well as the servicing of aircraft without
interfering with the aerodrome traffic. The guidance for holding bays and dual
or multiple taxiways, which describes the advantages and disadvantages of the
different configurations, is aimed at providing aerodrome controllers with
greater flexibility in adjusting the take-off sequence to overcome undue
delays. The guidance concerning aprons describes, inter alia, basic apron layouts,
design requirements and the area required for a particular apron layout.
This manual also includes
guidance for the segregation of traffic on the movement area and considerations
for designing aerodrome facilities in order to achieve the maximum practical
segregation of aircraft and ground vehicular traffic.
2.2 The purpose of this
manual is to assist in the implementation of the specifications described above
and help ensure their uniform application.
CHAPTER 1
TAXIWAYS
1.1 TAXIWAY SYSTEMS
Functional
requirements
1.1.1 Maximum
capacity and efficiency of an aerodrome are realized only by obtaining the
proper balance between the need for runways, passenger and cargo terminals, and
aircraft storage and servicing areas. These separate and distinct aerodrome
functional elements are linked by the taxiway system. The components of the
taxiway system therefore serve to link the aerodrome functions and are
necessary to develop optimum aerodrome utilization.
1.1.2 The taxiway system
should be designed to minimize the restriction of aircraft movement to and from
the runways and apron areas. A properly designed system should be capable of
maintaining a smooth, continuous flow of aircraft ground traffic at the maximum
practical speed with a minimum of acceleration or deceleration. This
requirement ensures that the taxiway system will operate at the highest levels
of both safety and efficiency.
1.1.3 For any given aerodrome,
the taxiway system should be able to accommodate (without significant delay) the
demands of aircraft arrivals and departures on the runway system. At low levels
of runway utilization the taxiway system can accomplish this with a minimum number
of components. However, as the runway acceptance rate increases, the taxiway
system capacity must be sufficiently expanded to avoid becoming a factor which
limits aerodrome capacity. In the extreme case of runway capacity saturation,
when aircraft are arriving and departing at the minimum separation distances,
the taxiway system should allow aircraft to exit the runway as soon as
practical after landing and to enter the runway just before take-off. This enables
aircraft movements on the runway to be maintained at the minimum separation
distance.
Planning principles
1.1.4 Runways and
taxiways are the least flexible of the aerodrome elements and must therefore be
considered first when planning aerodrome development. Forecasts of future
activity should identify changes in the rate of aircraft movements, the nature
of the traffic, type of aircraft and any other factors affecting the layout and
dimensioning of the runway and taxiway systems. Care should be taken not to
place so much attention on the present needs of the system that later phases of
development that have equal or greater importance are neglected. For example,
if an aerodrome is forecast to serve a higher category of aircraft type in the
future, the current taxiway system should be designed to accommodate the
greatest separation distances that ultimately will be required (see Table 1-1).
1.1.5 In planning the
general layout of the taxiway system, the following principles should be
considered:
a) taxiway routes
should connect the various aerodrome elements by the shortest distances, thus
minimizing both taxiing time and cost;
b) taxiway routes
should be as simple as possible in order to avoid pilot confusion and the need
for complicated instructions;
c) straight runs of
pavement should be used wherever possible. Where changes in direction are necessary,
curves of adequate radii, as well as fillets or extra taxiway width, should be
provided to permit taxiing at the maximum practical speed (see Section 1.4 and
Appendix 1);
d) taxiway crossings
of runways and other taxiways should be avoided whenever possible in the interests
of safety and to reduce the potential for significant taxiing delays;
e) taxiway routings should
have as many one-way segments as possible to minimize aircraft conflicts and delay.
Taxiway segment flows should be analysed for each configuration under which
runway(s) will be used;
f) the taxiway system
should be planned to maximize the useful life of each component so that future
phases of development incorporate sections from the current system; and
g) ultimately, a taxiway
system will perform only as well as its least adequate component. Therefore,
potential bottlenecks should be identified and eliminated in the planning
phase.
1.1.6 Other important
considerations when planning a taxiway system include the following:
a) taxiway routes
should avoid areas where the public could have easy access to the aircraft. Security
of taxiing aircraft from sabotage or armed aggression should be of primary
importance in areas where this is of particular concern;
b) taxiway layouts
should be planned to avoid interference with navigation aids by taxiing aircraft
or ground vehicles using the taxiway;
c) all sections of
the taxiway system should be visible from the aerodrome control tower. Remote
cameras can be used to monitor sections of taxiways shadowed by terminal
buildings or other aerodrome structures if such obstructions cannot be
practically avoided;
d) the effects of jet
blast on areas adjacent to the taxiways should be mitigated by stabilizing loose
soils and erecting blast fences where necessary to protect people or structures
(see Appendix 2); and
e) the location of taxiways
may also be influenced by ILS installations due to interferences to ILS signals
by a taxiing or stopped aircraft. Information on critical and sensitive areas
surrounding ILS installations is contained in Annex 10, Volume I, Attachment C.
Table
1-1. Design criteria for a taxiway
Outer
main gear wheel span
|
Physical
characteristics
|
Up
to but not including 4.5 m
|
4.5
m up to but not including 6 m
|
6
m up to but not including 9 m
|
9
m up to but not including 15 m
|
9
m up to but not including 15 m
|
9
m up to but not including 15 m
|
Minimum width of:
|
|
|
|
|
|
|
taxiway
pavement
|
7.5
m
|
10.5
m
|
17
ma
15
mb,c
|
23
mc
|
23
m
|
23
m
|
graded
portion of taxiway strip
|
20.5
m
|
22
m
|
25
m
|
37
m
|
38
m
|
44
m
|
Minimum clearance
distance of outer main wheel to taxiway edge
|
1.5
m
|
2.25
m
|
4.0
ma
3
mb
|
4.0
m
|
4.0
m
|
4.0
m
|
|
Code
letter
|
Physical
characteristics
|
A
|
B
|
C
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D
|
E
|
F
|
Minimum width of
|
|
|
|
|
|
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taxiway pavement
and shoulder
|
-
|
-
|
25
m
|
34
m
|
38
m
|
44
m
|
taxiway strip
|
31
m
|
40
m
|
52
m
|
74
m
|
87
m
|
102
m
|
Minimum separation
distance between taxiway centre line and: centre line of instrument runway
code
|
|
|
|
|
|
|
number 1
number 2
number 3
number 4
|
77.5
m
77.5
m
-
-
|
82
m
82
m
152
m
-
|
88
m
88
m
158
m
158
m
|
-
-
166
m
166
m
|
-
-
172.5
m
172.5
m
|
-
-
180
m
180
m
|
centre line of
non-instrument runway code
|
|
|
|
|
|
|
number 1
|
37.5
m
|
42
m
|
48
m
|
-
|
-
|
-
|
number 2
|
47.5
m
|
52
m
|
58
m
|
-
|
-
|
-
|
number 3
|
-
|
87
m
|
93
m
|
101
m
|
107.5
m
|
115
m
|
number 4
|
-
|
-
|
93
m
|
101
m
|
107.5
m
|
115
m
|
taxiway centre line
object
|
23
m
|
32
m
|
44
m
|
63
m
|
76
m
|
91
m
|
taxiwayd
|
15.5
m
|
20
m
|
26
m
|
37
m
|
43.5
m
|
51
m
|
aircraft stand
taxilane
|
12
m
|
16.5
m
|
22.5
m
|
33.5
m
|
40
m
|
47.5
m
|
|
|
|
|
|
|
|
Maximum
longitudinal slope of taxiway:
|
|
|
|
|
|
|
pavement
|
3%
|
3%
|
1.5%
|
1.5%
|
1.5%
|
1.5%
|
change in slope
|
1%
per 25 m
|
1%
per 25 m
|
1%
per 30 m
|
1%
per 30 m
|
1%
per 30 m
|
1%
per 30 m
|
Maximum transverse
slope of:
|
|
|
|
|
|
|
taxiway pavement
|
2%
|
2%
|
1.5%
|
1.5%
|
1.5%
|
1.5%
|
graded portion of
taxiway strip upwards
|
3%
|
3%
|
2.5%
|
2.5%
|
2.5%
|
2.5%
|
graded portion of
taxiway strip downwards
|
5%
|
5%
|
5%
|
5%
|
5%
|
5%
|
ungraded portion of
strip upwards or downwards
|
5%
|
5%
|
5%
|
5%
|
5%
|
5%
|
|
Code
letter
|
Physical
characteristics
|
A
|
B
|
C
|
D
|
E
|
F
|
Minimum radius of
longitudinal vertical curve
|
2
500 m
|
2
500 m
|
3
000 m
|
3
000 m
|
3
000 m
|
3
000 m
|
Minimum taxiway
sight distance
|
150
m from
|
200
m from
|
300
m from
|
300
m from
|
300
m from
|
300
m from
|
|
1.5
m above
|
2
m above
|
3
m above
|
3
m above
|
3
m above
|
3
m above
|
a. Taxiway intended
to be used by aeroplanes with a wheel base equal to or greater than 18 m.
b. Taxiway intended
to be used by aeroplanes with a wheel base less than 18 m.
c. On straight portions.
d. Taxiway other than
an aircraft stand taxilane.
1.1.7 There should be
a sufficient number of entrance and exit taxiways serving a specific runway to accommodate
the current demand peaks for take-offs and landings. Additional entrances and
exits should be designed and developed ahead of expected growth in runway
utilization. The following principles apply to the planning of these taxiway system
components:
a) the function of exit
taxiways is to minimize the runway occupancy time of landing aircraft. In
theory, exit taxiways can be located to best serve each type of aircraft
expected to use the runway. In practice, the optimum number and spacing are
determined by grouping the aircraft into a limited number of classes based upon
landing speed and deceleration after touchdown;
b) the exit taxiway should
allow an aircraft to move off the runway without restriction to a point clear
of the runway, thus allowing another operation to take place on the runway as
soon as possible;
c) an exit taxiway
can be either at a right angle to the runway or at an acute angle.
The former type
requires an aircraft to decelerate to a very low speed before turning off the
runway, whereas the latter type allows aircraft to exit the runway at higher
speeds, thus reducing the time required on the runway and increasing the runway
capacity (details about the location and geometry of the acute angle type
[called rapid exit taxiway] are presented in Section 1.3 and Appendix 5); and
d) a single runway
entrance at each end of the runway is generally sufficient to accommodate the
demand for take-offs. However if the traffic volume warrants, the use of bypasses,
holding bays or multiple runway entrances can be considered (see Chapter 2).
1.1.8 Taxiways
located on aprons are divided into two types as follows (see Figure 1-1):
a) apron taxiway is a
taxiway located on an apron and intended either to provide a through taxi route
across the apron or to gain access to an aircraft stand taxilane; and
b) aircraft stand taxilane
is a portion of an apron designated as a taxiway and intended to provide access
to aircraft stands only.
1.1.9 The
requirements for apron taxiways regarding strip width, separation distances,
etc., are the same as for any other type of taxiway. The requirements for
aircraft stand taxilanes are also the same except for the following
modifications:
a) the transverse
slope of the taxilane is governed by the apron slope requirement;
b) the aircraft stand
taxilane does not need to be included in a taxiway strip; and
c) the requirements
for the separation distances from the centre line of the taxilane to an object
are less stringent than those for other types of taxiways.
1.1.10 Aircraft stand
lead-in lines, which branch off to the parking positions, are not considered to
be a part of the aircraft stand taxilane and, therefore, are not subject to the
requirements for taxiways.
1.1.11 Figure 1-2
provides a reference to the minimum separate distances as provided in Table 3-1
of Annex 14, Volume I, for each of the taxiways and taxilanes mentioned in
Figure
Stages
in taxiway system development
1.1.12 To minimize
current construction costs, an aerodrome’s taxiway system should be only as
complex as needed to support the near-term capacity needs of the runway. With
careful planning, additional taxiway components can be added to the system in
stages to keep pace with the growth in aerodrome demand. Different stages in
taxiway system development are described in the following paragraphs (see
Figure 1-3):
a) a minimum aerodrome
taxiway system, supporting a low level of runway utilization, can consist of
only turnaround pads or taxiway turnarounds at both ends of the runway and a
stub taxiway from the runway to the apron;
b) traffic growth
which results in a low to moderate level of runway utilization may be accommodated
by building a partial parallel taxiway to connect one or both turnarounds
(parallel taxiways provide safety benefits as well as greater efficiency);
c) as runway utilization
increases, a full parallel taxiway can be provided by completing the missing
sections of the partial parallel taxiway;
d) exit taxiways, in
addition to the ones at each runway end, can be constructed as runway
utilization increases toward saturation;
e) holding bays and bypass
taxiways can be added to further enhance runway capacity. These facilities
seldom restrict the attainment of full aerodrome capacity within the existing
aerodrome property because land is usually available to permit their
construction; and
f) a dual-parallel
taxiway, located outboard of the first parallel taxiway, should be considere`d
when movement in both directions along the taxiway is desirable. With this
second taxiway, a one-way flow network can be established for each direction of
runway use. The need for the dual-parallel system increases in proportion to
the amount of development alongside the taxiway.
For additional
information, see the Airport Planning Manual (Doc 9184), Part 1 - Master
Planning.
Figure
1-1. Taxiways on aprons
Figure
1-2. Taxiway minimum separation distances
a)
Angular turnaround
b)
Circular turnaround
Figure
1-3. Turnarounds
Figure
1-3. Turnarounds (cont.)
Evaluating
taxiway layout alternatives
1.1.13 An evaluation
of alternative taxiway systems must take into account the operating efficiency
of each system in combination with the runway and apron layouts it is designed
to serve. The greater the complexity of the runway, taxiway and apron layouts,
the greater the possibility for reducing operating costs through a comparison
of alternative taxiway systems. Several computerized aircraft traffic flow
simulation models have been developed for this purpose by consultants, aircraft
operators and airport authorities.
1.1.14 For example,
the United States Federal Aviation Administration has the Airfield Delay Model
which simulates all significant aircraft movements performed on an aerodrome
and its runway approach paths during an extended period of time. Such models
are able to consider a variety of input variables such as:
- aircraft mix;
- traffic volume;
- traffic peaking;
- aerodrome layouts
(taxiway and runway);
- terminal destinations
of aircraft;
- runway
configurations;
- taxiway
configurations;
- rapid exit taxiways;
and
- use of particular
runways by categories of aircraft.
From these inputs, these
models produce outputs for evaluation and comparison which include:
- taxiing fuel costs;
- taxiing distances;
- taxiing travel times;
- taxiing delays; and
- runway arrival
anddeparture delays.
Aircraft
taxi distances
1.1.15 The main
reason to minimize aircraft taxi distances is to reduce taxi time and thus save
fuel and enhance aircraft utilization and safety. Of particular importance are
the taxi distances for the heavily loaded aircraft taxiing for take-off. Even
small airports should have layouts which recognize this need.
1.1.16 At larger airports
the issue of aircraft safety has greater significance. Detailed investigations
have shown that when a fully laden aircraft is taxied over a distance varying
from 3 to 7 km (depending upon the aircraft type, its tire size and type, and the
ambient temperature), the tire carcass temperature during take-off can exceed a
critical value of 120°C (250°F). Exceeding this critical temperature affects the
nylon cord strength and rubber adhesion of the tire and significantly increases
the risk of tire failure. The 120°C limit used in the industry applies to
taxiing for take-off as well as the take-off run. At 120°C the nylon tensile
strength is reduced by 30 per cent. Higher temperatures cause permanent
deterioration of rubber adhesive properties. Tire failures during take-off are
serious because they can result in an aborted take-off with braking being
ineffective on those wheels having blown tires.
1.1.17 Taxi distances
should therefore be kept to the minimum practicable. In the case of large
wide-bodied aircraft, a distance of 5 km is considered to be the acceptable
upper limit, and where unfavourable factors exist, such as those which require
frequent use of brakes, this limit may have to be reduced.
1.1.18 Every airport
master plan, irrespective of the size of the airport development, should
recognize the need to minimize taxi distances, especially for departing aircraft,
for both economy and safety. The suitable location of rapid exit taxiways can
do much to reduce taxi distances for landing aircraft. Further, take-offs from
taxiway intersections and the use of rapid exit taxiways not only reduce taxi
distances and runway occupancy time but also increase runway capacity.
1.2 PHYSICAL CHARACTERISTICS DESIGN CRITERIA
General
1.2.1 Design criteria
for taxiways are less stringent than those for runways since aircraft speeds on
taxiways are much slower than those on runways. Table 1-1 shows the main
physical characteristics design criteria recommended for a taxiway in
accordance with the specifications in Annex 14, Volume I. It should be emphasized
that with respect to the clearance distance between the outer main wheel of the
aircraft and the edge of the taxiway, it is assumed that the cockpit of the
aircraft remains over the taxiway centre line markings.
Aerodrome
reference code
1.2.2 The reference code
is intended to provide a simple method for interrelating the numerous specifications
concerning the characteristics of aerodromes to ensure that the aerodrome facilities
are suitable for the aeroplanes that are intended to operate at the aerodrome. The
code is composed of two elements which are related to the aeroplane performance
characteristics and dimensions. Element 1 is a number based on the aeroplane
reference field length, and Element 2 is a letter based on the aeroplane
wingspan.
1.2.3 A particular
specification is related to the more appropriate of the two elements of the
code or to an appropriate combination of the two code elements. The code letter
or number within an element selected for design purposes is related to the critical
aeroplane characteristics for which the facility is provided. When applying the
relevant specifications in Annex 14, Volume I, the aeroplanes which the
aerodrome is intended to serve are identified first followed by the two
elements of the code.
1.2.4 An aerodrome
reference code - a code number and a letter - selected for aerodrome planning
purposes shall be determined in accordance with the characteristics of the
aeroplane for which an aerodrome facility is intended. Further, the aerodrome
reference code numbers and letters shall have the meanings assigned to them in Table
1 - 2. A classification of representative aeroplanes by code number and code
letter is included in Appendix 3.
1.2.5 The code number
for Element 1 shall be determined from Table 1-2, selecting the code number
corresponding to the highest value of the aeroplane reference field lengths of
the aeroplanes for which the runway is intended. The aeroplane reference field
length is defined as the minimum field length required for take-off at maximum
certificated take-off mass, sea level, standard atmospheric conditions, still air
and zero runway slope, as shown in the appropriate aeroplane flight manual
prescribed by the certificating authority or equivalent data from the aeroplane
manufacturer. Accordingly, if 1 650 m corresponds to the highest value of the
aeroplane reference field lengths, the code number selected would be “3”.
1.2.6 The code letter
for Element 2 shall be determined from Table 1-2, selecting the code letter
which corresponds to the greatest wing span of the aeroplanes for which the
facility is intended.
1.2.7 The wingspan component
is relevant for aerodrome characteristics related to separation distances (e.g.
obstacles, strips), while outer main gear wheel span (OMGWS) components impact ground-based
manoeuvring characteristics (e.g. runway and taxiway widths). The two
determining components should be used separately, since using the most
demanding component may cause overdesign, either for separations or
runway/taxiway width for some aeroplane types. As the OMGWS is the relevant
parameter for determining runway width, taxiway width and graded portion of taxiway
strips, it is referenced directly in the relevant provisions to avoid the
complexity of a third code element.
Table
1-2. Aerodrome reference code
Code
element 1
|
Code
number
|
Aeroplane reference
field length
|
1
|
Less than 800 m
|
2
|
800 m up to but not
including 1 200 m
|
3
|
1 200 m up to but
not including 1 800 m
|
4
|
1 800 m and over
|
Code
element 2
|
Code
letter
|
Wingspan
|
A
|
Up to but not
including 15 m
|
B
|
15 m up to but not
including 24 m
|
C
|
24 m up to but not
including 36 m
|
D
|
36 m up to but not
including 52 m
|
E
|
52 m up to but not
including 65 m
|
F
|
65 m up to but not
including 80 m
|
Table
1-3. Aircraft speeds versus radius of curve
Speed
(km/h)
|
Radius
of curve
(m)
|
16
|
15
|
32
|
60
|
48
|
135
|
64
|
240
|
80
|
375
|
96
|
540
|
Taxiway
width
1.2.8 Minimum taxiway
widths are shown in Table 1-1. The values selected for the minimum taxiway
widths are based on adding clearance distance from wheel to pavement edge to
the maximum OMGWS within its category.
Taxiway
curves
1.2.9 Changes in
direction of taxiways should be as few and small as possible. The design of the
curve should be such that when the cockpit of the aeroplane remains over the
taxiway centre line markings, the clearance distance between the outer main
wheels of the aeroplane and the edge of the taxiway should not be less than
those specified in Table 1-1.
1.2.10 If curves are unavoidable,
the radii should be compatible with the manoeuvring capability and normal
taxiing speeds of the aircraft for which the taxiway is intended. Table 1-3
shows values of allowable aircraft speeds for given radii of curvature based on
a lateral load factor of 0.133 g (see 1.2.23). Where sharp curves are planned
and their radii will not suffice to prevent wheels of taxiing aircraft from
leaving the pavement, it may be necessary to widen the taxiway so as to achieve
the wheel clearance specified in Table 1-1. It is to be noted that compound
curves may reduce or eliminate the need for extra taxiway width.
Junctions
and intersections
1.2.11 To ensure that
the minimum wheel clearance distances specified in Table 1-1 are maintained,
fillets should be provided at junctions and intersections of taxiways with
runways, aprons and other taxiways. Information on the design of fillets is
given in 1.5.
Taxiway
minimum separation distances
General
1.2.12 The separation
distance between the centre line of a taxiway and the centre line of a runway,
another taxiway or an object should not be less than the appropriate dimension
specified in Table 1-1. It may, however, be permissible to operate with lower separation
distances at an existing aerodrome if an aeronautical study indicates that such
lower separation distances would not adversely affect the safety or significantly
affect the regularity of operations of aeroplanes. Guidance on factors which
may be considered in the aeronautical study is given in 1.2.29 through 1.2.67.
1.2.13 The distances
are based on the maximum wing span of a group and on the deviation of one
aircraft from the taxiway centre line a distance equal to the wheel-to-edge
clearance and the increment (Z) for that group. It should be noted that,
even in instances where a particular aircraft design (as a result of an unusual
combination of large wing span and narrow gear span) might result in the wing
tip extending farther from the centre line distance, the resulting clearance
distance would still be considerably more than that required for aircraft to
pass.
Separation distances
between taxiways, and between taxiways and objects
1.2.14 Formulas and
separation distances are shown in Table 1-4 and illustrated in Figure 1-4. The
separation distances related to taxiways and apron taxiways are based on the
aircraft wing span (Y) and the maximum lateral deviation (X) (the
wheel-to-edge clearance specified in Table 1-1).
Table
1-4. Minimum separation distances between taxiways and between taxiways and
objects (dimensions in metres)
|
Code
letter
|
Separation
distances
|
A
|
B
|
C
|
D
|
E
|
F
|
Between apron
taxiway/taxiway centre line and apron taxiway/taxiway centre line:
|
|
|
|
|
|
|
wing span (Y)
|
15.0
|
24.0
|
36.0
|
52.0
|
65.0
|
80.0
|
+ maximum lateral
deviation (X)
|
1.5
|
2.25
|
3.0
|
4.0
|
4.0
|
4.0
|
+ increment (Z)
|
6.5
|
5.75
|
5.0
|
7.0
|
7.0
|
7.0
|
Total separation
distance (V)
|
23.0
|
32.0
|
44.0
|
63.0
|
76.0
|
91.0
|
|
|
|
|
|
|
|
Between apron
taxiway/taxiway centre line and object:
|
|
|
|
|
|
|
1/2 wing span (Y)
|
7.5
|
12.0
|
18.0
|
26.0
|
32.5
|
40.0
|
+ maximum lateral
deviation (X)
|
1.5
|
2.25
|
3.0
|
4.0
|
4.0
|
4.0
|
+ increment (Z)
|
6.5
|
5.75
|
5.0
|
7.0
|
7.0
|
7.0
|
Total separation
distance (V)
|
15.5
|
20.0
|
26.0
|
37.0
|
43.5
|
51.0
|
|
|
|
|
|
|
|
Between aircraft
stand taxilane centre line and aircraft stand taxilane centre line
|
|
|
|
|
|
|
wing span (Y)
|
15.0
|
24.0
|
36.0
|
52.0
|
65.0
|
80.0
|
+ gear deviation
|
1.5
|
1.5
|
1.5
|
2.5
|
2.5
|
2.5
|
+ increment (Z)
|
3.0
|
3.0
|
3.0
|
5.0
|
5.0
|
5.0
|
Total separation
distance (V)
|
19.5
|
28.5
|
40.5
|
59.5
|
72.5
|
87.5
|
|
|
|
|
|
|
|
Between aircraft
stand taxilane centre line and object:
|
|
|
|
|
|
|
1/2 wing span (Y)
|
7.5
|
12.0
|
18.0
|
26.0
|
32.5
|
40.0
|
+ gear deviation
|
1.5
|
1.5
|
1.5
|
2.5
|
2.5
|
2.5
|
+ increment (Z)
|
3.0
|
3.0
|
3.0
|
5.0
|
5.0
|
5.0
|
Total separation
distance (V)
|
12.0
|
16.5
|
22.5
|
33.5
|
40.0
|
47.5
|
1.2.15 Lesser distances
on aircraft stand taxilanes are considered appropriate because taxiing speeds
are normally lower when taxiing on these taxiways, and the increased attention
of pilots results in less deviation from the centre line. Accordingly, instead
of assuming an aircraft is off the centre line as far as the maximum lateral deviation
(X) would allow, a lesser distance is assumed which is referred to as
“gear deviation”.
1.2.16 It may be
noted that two factors have been used in the development of the formulas: the
maximum lateral deviation/gear deviation and the wing tip clearance increment.
These factors have different functions. The deviation factor represents a
distance that aircraft might travel in normal operation. On the other hand, the
increment (Z in Figure 1-4) is a safety buffer intended to avoid accidents
when aircraft go beyond the taxiway, to facilitate taxiing by providing extra
space, and to account for other factors influencing taxiing speeds.
1.2.17 A graduated
increment scale rather than a constant increment for all code letters has been
selected because:
a) pilot judgement of
clearance distance is more difficult in aircraft with larger wing spans,
particularly when the aircraft has swept wings; and
b) the momentum of
larger aircraft may be higher and could result in such aircraft running farther
off the edge of a taxiway.
1.2.18 The increments
for the determination of the separation distances between an apron taxiway and
an object are the same as those proposed between a taxiway and an object, the
reason being that although apron taxiways are associated with aprons, it is
thought that their location should not imply a reduction in taxiing speed.
Aircraft will normally be moving at slow speeds on an aircraft stand taxilane
and can therefore be expected to remain close to the centre line. A deviation
of 1.5 m has been selected for code letters A to C. A deviation of 2.5 m has
been adopted for code letters D to F. The use of a graduated scale for lateral
deviation in a stand taxilane is considered appropriate since the ability of a
pilot to follow the centre line is decreased in larger aircraft because of the
cockpit height.
U = Main gear span
|
X = Maximum lateral
deviation
|
V = Separation
distance
|
Y = Wing span
|
W = Taxiway width
|
Z = Increment
|
Figure
1-4. Separation distance to an object
1.2.19 Larger increments
have been selected for the separation distances between taxiway/object and apron
taxiway/object than for other separation distances. These larger increments are
considered necessary because normally objects along such taxiways are fixed
objects, thus making the probability of a collision with one of them greater
than that of one aircraft running off the taxiway just as another aircraft is
passing that point on the parallel taxiway. Also, the fixed object may be a
fence or wall which runs parallel to the taxiway for some distance. Even in the
case of a road running parallel to a taxiway, vehicles may unknowingly reduce
the clearance distance by parking off the road.
Separation distances
between taxiways and runways
1.2.20 The separation
distances are based on the concept of the wing of an aircraft centred on a parallel
taxiway remaining clear of the associated runway strip. The formulas and
separation distances are shown in Table 1 -5. The separation distance between
the centre lines of a runway and a parallel taxiway is based on the accepted
principle that the wing tip of an aeroplane taxiing on the parallel taxiway
should not penetrate the associated runway strip. However this minimum separation
distance may not provide adequate length for the link taxiway connecting the parallel
taxiway and the runway to permit safe taxiing of another aircraft behind an
aircraft holding short of the runway at the holding position. To permit such
operations, the parallel taxiway should be so located as to comply with the
requirements of Annex 14, Volume I, Tables 3-1 and 3-2, considering the
dimensions of the most demanding aeroplane in a given aerodrome code. For
example, at a code E aerodrome, this separation would be equal to the sum of
the distance of the runway holding position from the runway centre line, plus
the overall length of the most demanding aeroplane, and the taxiway-to-object
distance specified in column E of Table 1-1.
Table
1-5. Minimum separation distances between taxiway/apron taxiway centre line and
runway centre line (dimensions in metres)
Code
number
|
1
|
2
|
3
|
4
|
|
A
|
B
|
A
|
B
|
A
|
B
|
C
|
D
|
C
|
D
|
E
|
F
|
1/2
wing span (Y)
+
1/2 strip width
|
7.5
|
12
|
7.5
|
12
|
7.5
|
12
|
18
|
26
|
18
|
26
|
32.5
|
40
|
(non-instrument
approach runway)
|
30
|
30
|
40
|
40
|
75
|
75
|
75
|
75
|
75
|
75
|
75
|
75
|
Total
|
37.5
|
42
|
47.5
|
52
|
82.5
|
87
|
93
|
101
|
93
|
101
|
107.5
|
115
|
or
1/2 wing span (Y)
|
7.5
|
12
|
7.5
|
12
|
7.5
|
12
|
18
|
26
|
18
|
26
|
32.5
|
40
|
+
1/2 strip width
|
|
|
|
|
|
|
|
|
|
|
|
|
(instrument
approach runway)
|
70
|
70
|
70
|
70
|
140
|
140
|
140
|
140
|
140
|
140
|
140
|
140
|
Total
|
77.5
|
82
|
77.5
|
82
|
147.5
|
152
|
158
|
166
|
158
|
166
|
172.5
|
180
|
Parallel
taxiway geometry
1.2.21 The separation
distances between parallel taxiways shown in Table 1-1 have been selected on
the basis of desired wing tip clearances. There are other factors which should
also be taken into account when evaluating the capability of making a normal
180-degree turn from one taxiway to another parallel taxiway. These include:
a) maintaining a
reasonable taxi speed to achieve high taxiway system utilization;
b) maintaining
specified clearance distances between the outer main wheel and the taxiway edge
when the cockpit remains over the taxiway centre marking; and
c) manoeuvring at a
steering angle that is within the capability of the aircraft and which will not
subject the tires to unacceptable wear.
1.2.22 To evaluate
the taxi speed when making the 180-degree turn, it is assumed that the radii of
curvature are equal to one-half of the separation distance indicated in Table
1-1, and as shown below:
Code
letter
|
Radius
(m)
|
A
|
11.5
|
B
|
16.0
|
C
|
22.0
|
D
|
31.5
|
E
|
38.0
|
F
|
45.5
|
1.2.23 The velocity
in the turn is a function of the radius of the curve (R) and the lateral
load factor (f). Thus, if it is assumed that the lateral load factor is
limited to 0.133 g:
V
= (127.133
x (f) x R)1/2
=
(127.133
x 0.133 R) 1/2
=
4.1120(
R1/2),
where R is in
metres.
The resulting
allowable velocities are shown in Table 1-6.
1.2.24 Examination of
Table 1-6 shows that a velocity of 25.4 km/h is achieved for code letter E. In
the case of code letter F, the velocity would be 27.7 km/h. To achieve the same
speed on taxiways associated with the other code letters, a separation distance
of 80 m would be required. The separation distances for code letters A and B,
however, may be unreasonably large when compared with those required by the
desired wing tip clearance. In this connection, experience shows that small
aircraft require a slower speed than larger aircraft because of their
sensitivity to nose gear swivelling.
1.2.25 To evaluate
the factors mentioned in 1.2.21 b) and c), a computer programme was developed
by an aircraft manufacturer to show the motion of an aircraft during a
180-degree turn. A representative aircraft from each code letter was used (see
Table 1-6). These aircraft were chosen for illustrative purposes because they
have the greatest distance between the main gear and the cockpit of the
aircraft within each code. The radius of the curve for each case is based on
one-half of the minimum separation distance.
1.2.26 The ability to
make a smooth turn depends, in part, on the allowable steering angle. Table 1-7
provides data for the representative aircraft. (The data shown in the last
column are based on the data of Table 1 -6 and assume 3-degree nose tire slip
for Lear 55, F28 and MD80, and 5-degree nose tire slip for MD11 and B747.) The
study revealed that the maximum angle required during the turn is within the
limits given in Table 1-7 for all aircraft.
1.2.27 The solution for
a 180-degree turn, which was arrived at by use of a computer programme, can
also be determined by graphical means. The procedure requires a step-by- step
movement of the cockpit along the centre line of the curve. The main gear is
assumed to travel along a line that is formed by the original position of the
mid-point between the main gear and the new position of the cockpit. This is
illustrated in Figure 1-5.
1.2.28 It is significant
to note that the computer programme results were based on increments of
movement of 0.5 degrees. This is much too tedious for a graphical solution, and
a comparison was made of the computer programme solution with a graphical
solution in which the increments were 10 degrees. It was concluded that an
error of approximately 2.4 m is introduced by the coarser increments of the
graphical method. Increments of 5 degrees will reduce the error to
approximately 1.5 m.
Table
1-6. Assumed data for calculation of 180-degree turn
|
Radius
of curvature
(m)
|
|
Main
gear to cockpit
(m)
|
Velocity
V = 4.1120 (R1/2)
(km/h)
|
Code
letter
|
Critical
aircraft mode
|
A
|
11.5
|
Lear
55
|
5.7
|
14.0
|
|
|
|
|
|
B
|
16.0
|
F28
|
11.9
|
16.5
|
C
|
22.0
|
MD80
|
20.3
|
19.3
|
D
|
31.5
|
MD11
|
31.0
|
23.1
|
E
|
38.0
|
A340-600
|
37.4
|
25.4
|
E
|
38.0
|
B747
|
27.8
|
25.4
|
E
|
38.0
|
B777-300
|
34.2
|
25.4
|
F
|
45.5
|
A380
|
31.9
|
27.7
|
Table 1-7. Aircraft
steering angles
|
Maximum
steering angle
|
Approx.
steering angle during 180-degree turn
|
Aircraft
model
|
|
|
Lear
55
|
55°
|
40°
|
F28
|
76°
|
45°
|
MD80
|
82°
|
65°
|
MD11
A340-600
|
72°
75°
|
70°
70°
|
B747
|
70°
|
50°
|
B777-300
|
70°
|
65°
|
A380
|
70°
|
45°
|
Figure
1-5. Graphical solution of a 180-degree turn
Radius
of curvature
and path of cockpit
Aeronautical
study relating to minimum separation distances
Introduction
1.2.29 The aim of the
specifications in Annex 14, Volume I, is to give aerodrome planners a tool to
design efficient aerodromes for safe aircraft operations. It is not intended,
however, that the Annex be used to regulate aircraft operations. It may be
permissible to operate at existing aerodromes with lower taxiway separation
distances than those specified in the Annex if an aeronautical study indicates
that such lower separation distances would not adversely affect the safety or
significantly affect the regularity of operations of aircraft. The purpose of
this material is to assist States in undertaking an aeronautical study by
defining the criteria considered pertinent for the assessment of whether lesser
dimensions than those specified in Annex 14, Volume I, Table 3-1 (reproduced in
Table 1-1) are adequate for the operation of new larger aeroplanes in the
specific operational environment at an existing aerodrome. This may also result
in operational restrictions or limitations. Where alternative measures,
operational procedures and operating restrictions have been developed, their details
are reproduced in the aerodrome manual and reviewed periodically to assess their
continued validity. It is expected that infrastructure on an existing aerodrome
or a new aerodrome will fully comply with Annex 14, Volume I, specifications at
the earliest opportunity. Further guidance to assess the compatibility of the operation
of a new aeroplane with an existing aerodrome can be found in the Procedures
for Air Navigation Services (PANS) - Aerodromes (Doc 9981).
Objectives and scope
1.2.30 The prime objective
of an aeronautical study is to assess the adequacy of the protection provided
by the existing layout for the operation of the critical aircraft with respect to:
a) collision with
another aircraft, vehicle or object;
b) run-off from paved
surfaces; and
c) engine damage from
ingestion.
1.2.31 The areas of
concern which this assessment will address relate to specific functional
requirements in terms of:
a) Distance between
centre line of runway and centre line of taxiway;
b) Distance between
centre line of taxiway and centre line of parallel taxiway;
c) distance between
centre line of taxiway and object;
d) distance between
centre line of aircraft stand taxilane and object;
e) runway and taxiway
dimensions, surface and shoulders; and
f) protection of
engines against damage from foreign objects.
It should be noted
that every operational factor listed above need not be considered in all
instances. Therefore, the appropriate authority should determine which factors
are relevant to a risk analysis for a specific site. Additionally, the
appropriate authority should define the parameters for each of the operational
factors selected and assign a hierarchy of values to each of them, based upon
subjective operational and engineering judgements.
Basic considerations
1.2.32 Operational experience
with large aircraft at aerodromes not designed to the specifications dictated by
that aircraft type has shown that a safe and regular operation is feasible, though
subject to specific measures being implemented (the use of selected taxi
routings, designated aircraft stand taxilanes, etc.). This may be due to the
fact that a variety of adverse factors do not necessarily affect the
operational environment at a certain aerodrome. Furthermore, analyses of accidents
and incidents do not indicate that they are caused by inadequate margins that
do not meet the specifications in Annex 14, Volume I. It may thus be assumed that
the above considerations similarly apply to the operation of new larger
aeroplanes, subject to the conditions resulting from the aeronautical study.
Assessment aspects
1.2.33 An
aeronautical study will consist essentially of a risk analysis based on pertinent
criteria to assess:
a) probability of
collision;
b) probability of
run-off; and
c) risk of engine
ingestion.
The majority of
criteria being qualitative in nature, the assessment of risk levels cannot be
expressed in absolute or quantitative terms. For the outcome of the study to be
meaningful, it should be complemented by operational and engineering
judgements. This suggests that the appropriate authority should consult with the
aircraft operator when carrying out the assessment.
1.2.34 Referring to collision
risk assessment, which addresses the separation/clearance distances provided, the
relative risk level on the movement area (expressed in terms of probability of
a collision to occur) is generally considered to increase in the following
order of priority:
runway
→ taxiway → apron taxiway → aircraft stand taxilane
The increase in risk
is attributed to:
a) decreasing
accounting for aircraft deviations from the centre line/guideline and
associated incremental margins;
b) increasing density
of vehicles and objects; and
c) increasing complexity
of layouts giving rise to pilot distraction, confusion, misinterpretation, etc.
1.2.35 A crucial criterion
for assessing the adequacy of existing separation/clearance distances for safe
and regular operation of new larger aeroplanes is the accuracy with which
aircraft taxi relative to the centre line/guideline on runways and taxiways:
a) on straight
portions; and
b) on taxiway curves.
1.2.36 The following
factors can impact on the accuracy or safety achieved in day-to- day operational
environments and require, therefore, a detailed examination as applicable:
a) quality of
aircraft nose wheel guidelines (marking and lighting);
b) quality of signs;
c) visibility
conditions;
d) day or night;
e) surface state
(dry, wet, contaminated by snow/ice);
f) taxi speed;
g) pilots’ attention;
h) pilots’ technique
of negotiating turns;
i) wind effects
(cross-wind); and
j) aircraft handling
characteristics.
1.2.37 The provision of
taxiing guidance, i.e. marking, lighting and signs which are adequately conspicuous
in all operational conditions, together with good surface friction conditions,
is considered paramount for achieving a high degree of taxiing accuracy. This
is substantiated by the fact that the pilot of a large aeroplane, being unable
to see the wing tips, will have to rely primarily on taxiing guidance, the
accurate tracking of which will guarantee proper wing tip clearance.
1.2.38 Good surface friction
characteristics are required because nose wheel steering effectiveness can
become significantly degraded with large aeroplanes whenever the surface is
other than dry, thereby challenging the execution of controlled turns. This is
particularly true in the presence of a strong cross-wind.
1.2.39 The rationale
used for determining separation distances for code letters E and F assumes a
lateral deviation value of 4.0 m from the centre line for taxiways/apron
taxiways on either straight or curved portions. For aircraft stand taxilanes
the respective value is 2.5 m and is referred to as gear deviation.
1.2.40 Taxiway
deviation studies, using a representative mix of aircraft types including large
aeroplanes, were conducted at London/Heathrow and Amsterdam/Schiphol airports
(see Appendix 4). Results suggest that in favourable operating conditions (i.e.
positive guidance provided by centre line lighting and marking and good surface
friction characteristics), the mean deviation of main gears of aircraft from
the centre line on straight taxiway portions is less than 4.5 m. It should be
noted here, however, that the value of maximum deviation of main gears of most
aircraft reached the 8 to 10 m range depending on aircraft type. With these
provisions, a reduction of the deviation value accounted for in an aeronautical
study may be acceptable relative to straight portions of taxiways, whereas the
specified value should be retained if the above conditions are not met.
1.2.41 For taxiway
curves, however, the situation is somewhat different. A fixed deviation of 4.0
m seen as adequate for defining separation/clearance distances does not account
for the natural main gear track-in which results from the cockpit following the
centre line. For new larger aeroplanes, the track-in allowance may be inadequate
for the smaller turn radii of taxiways. Therefore, a detailed evaluation will
be required to determine the path followed by the wing tip on the inside of the
turn. For a detailed study involving other new larger aeroplanes, it may be
necessary to consult the aircraft manufacturers.
1.2.42 Design specifications
are based on the assumption that, in taxiway curves, the cockpit is following
the centre line of the taxiway. In day-to-day operations, however, pilots
frequently use the straight-through or oversteering technique. This alternative
practice may be taken into account when contemplating operations with reduced separation/clearance
distances. This may apply, for example, in the case of curved parallel taxiways
with the aircraft on the outer taxiway using the cockpit over the centre line
technique while the aircraft on the inner taxiway applies the oversteering
technique (e.g. main gear centre over centre line). Other measures of
importance are taxiway turn fillet size and wing tip clearance in the terminal
areas.
1.2.43 Apart from assessing
the adequacy of separation/clearance distances given the relatively small
deviations anticipated in normal operation, the aeronautical study may further
require an assessment of the probability of collision due to large inadvertent excursions
including run-offs from the paved surface.
1.2.44 Inadvertent
excursions are guarded against by using an appropriate safety buffer (increment
Z) which, however, does not make a differentiation with regard to the
degree of risk involved. Accordingly, it may be assumed that the specified margins
will provide adequate protection against a large variety of unfavourable
operational factors.
1.2.45 When
contemplating lesser margins, the study will have to determine the relative
probability of collision for the particular operational environment at the
aerodrome concerned. This entails an assessment of the total risk, composed of:
a) the risk of
run-offs; and
b) exposure to
collision risks;
and for which
separate criteria will apply:
for a):
- surface friction
conditions
- taxi speed
- straight or curvedtaxiway
- taxi-in or taxi-out;
for b):
- type of object
(fixed/mobile)
- extent or density of
objects
- affected part of the
movement area.
1.2.46 Expressed in
practical terms, the run-off risk is considered to increase with poor surface
friction characteristics (snow/ice) where taxi speeds are relatively high,
especially in taxiway curves. The exposure to collision risks increases with
the aircraft moving from the runway to the apron due to the increase in object
density (fixed and mobile) and the smaller margins provided. In a favourable
operational environment, however, it may be determined that the probability of collision
is extremely remote or improbable and therefore lesser separation/clearance
distances are acceptable. This may apply for an isolated object located along a
straight taxiway, low taxi speeds and good surface friction characteristics being
prevalent.
Considerations
related to specific functional requirements
Runway/taxiway
separation distances
1.2.47 The main
principle governing runway/taxiway separation distances is that the wing tip of
a taxiing aeroplane should not penetrate the strip of the associated runway.
Other major aspects requiring consideration concern the protection of an
aircraft that has inadvertently run off a runway against collision with another
aircraft taxiing on a parallel taxiway and the protection of the ILS critical
and sensitive areas against interference from radio navaids. The risk of a
collision occurring is essentially governed by:
a) the probability of
a run-off, and
b) the exposure to
collision risks,
and would have to be
assessed in a study for the particular operational environment existing at the
aerodrome concerned.
1.2.48 There is
statistical evidence that run-offs occur for a variety of causal factors and
with different degrees of lateral deviation from the runway centre line. The
risk of runway run-offs is significantly due to:
a) environmental
factors:
- poor runway surface
characteristics
- strong
cross-wind/gusts/wind shear;
b) aircraft operation
factors:
- human
- technical
failures/malfunctions (steering/tire/brake/reverse thrust failures).
1.2.49 While factors related
to aircraft operation are in general unpredictable, the environmental factors
are subject to control or monitoring by the appropriate authority so that
overall risks can be minimized. Furthermore, the exposure to collision risks is
largely affected by the magnitude of lateral deviation from the runway centre
line and the traffic density.
1.2.50 Guidance on
grading of strips for precision approach runways, taking into account lateral
deviations, is provided in Annex 14, Volume I, Attachment A, 9.3 and Figure
A-4. Relating the lateral dimensions to the existing separation distance may
assist in assessing the relative exposure to collision risks. For lesser separation
distances than those specified in Annex 14, Volume I, however, it would appear
advisable to make efforts to minimize run-off risks through effective control
and reporting of runway surface friction characteristics and reliable reporting
of wind conditions. Accordingly, aircraft operators can contribute to
minimizing run-off risks by applying operational restrictions commensurate with
reported conditions.
Taxiway/taxiway
separation distances
1.2.51 The separation
distances specified for parallel taxiways are intended to provide a safe wing
tip clearance by accounting for the anticipated deviation of a manoeuvring
aircraft from the taxiway centre line, in terms of:
a) taxiing accuracy
achieved in day-to-day operation; and
b) inadvertent
excursions/run-offs.
A study on whether lesser
distances provide adequate safety margins in the operational environment of an
existing aerodrome layout will require an assessment of the risk of collision
which, owing to different levels involved, should be related to:
a) straight parallel
taxiways; and
b) taxiway curves.
In either case, the
risk of collision between two aircraft on parallel taxiways is determined
primarily by the probability of an inadvertent major excursion by an aircraft
from the taxiway centre line.
2.2.52 In contrast,
taxiing accuracy per se is not considered to affect the collision risk to a
critical extent in the case of straight parallel taxiways.
2.2.53 On taxiway
curves, however, taxiing accuracy becomes a critical element in terms of
collision risks for the various reasons outlined in 1.2.33 through 1.2.46.
Accordingly, the trajectories of the wing tips of two large aircraft must be
established.
2.2.54 When contemplating
lesser separation distances, careful consideration must be given to the various
factors affecting taxiing accuracy (1.2.33 through 1.2.46), in particular
taxiway curves. In this regard, the maintenance of good surface friction
characteristics under all environmental circumstances is considered a dominant
prerequisite for minimizing:
a) lateral deviations
through proper nose-wheel steering and wheel-braking effectiveness; and
b) risks of run-off.
Accordingly, the
overall risk would be reduced essentially to the possibility of inadvertent
major excursions resulting from unpredictable technical failures affecting the steering
capability of an aircraft (e.g. nose-wheel steering). The assessment of the
overall risk would thus consist of:
a) the probability of
occurrence of a technical failure leading to a major excursion; and
b) the exposure to
collision risks subject to traffic density.
In the case of a)
above, however, there is no indication that the probability rate of mechanical
failures would be significant.
Taxiway/object
separation distances
2.2.55 The risk considerations
and the prerequisites related to reduced separation distances as outlined in
1.2.51 through 1.2.54 will similarly apply when assessing the adequacy of
actual separation distances between the taxiway centre line and objects at an
existing aerodrome. As far as the exposure to risks of collision is concerned,
particular attention appears warranted with respect to:
a) the nature of
objects (fixed or mobile);
b) their size
(isolated or extended); and
c) their location
relative to straight portions of taxiways or taxiway curves.
2.2.56 It is
reiterated that obstacles situated close to taxiway curves and adjacent areas
will require particular examination. This includes not only consideration of
wing tip clearances but also the possibility of impingement of jet wake on the
object as a result of aircraft changing direction at an intersection.
Apron taxiway/object
separation distances
2.2.57 In general,
the apron is considered an area of high activity involving a changing pattern
of obstacles of fixed/mobile and permanent or temporary nature in a variable
operating environment. Accordingly, aircraft operating along an apron taxiway may
be exposed to incomparably higher risks of collision as compared to aircraft
taxiing on a standard taxiway, margins accounted for by the formula in terms of
deviation and increment being the same. This is actually evidenced by the
comparatively high rate of reported incidents occurring on aprons, which is a matter
of continuing concern. There is, however, no indication of the incidents being
related to basic inadequacies of the specified minimum separation distances.
2.2.58 Nevertheless, it
may be reasonably assumed that at an aerodrome where lesser separation is
provided, there is increased potential for incidents to occur unless a set of
specific requirements relating to all critical elements involved in apron
activities is fulfilled.
2.2.59 Risks of
collision relate predominantly to mobile objects which may infringe upon
clearance distances relative to taxiing aircraft. Accordingly, a basic
requirement would be to segregate the operating area of an aircraft from the
respective area intended to be used by mobile objects (e.g. servicing vehicles and
equipment facilities). Specifically this would include:
a) for the aircraft:
- taxi guidelines
(marking and lighting);
b) for mobile
objects:
- apron safety lines
(see Annex 14, Volume I, Chapter 5)
- service road boundary
lines
- procedures and
regulations to ensure discipline.
1.2.60 Concerning taxi
guidance on aprons, it is of paramount importance, in order to minimize the risk
of major excursions, that the pilot be provided with a conspicuous and
unambiguous guideline which is visible continuously in all prevailing operating
conditions. This guideline is crucial for pilots of large aircraft who, being
unable to routinely observe the wing tip and having difficulty judging small
clearances, must follow the designated guidelines as closely as practicable.
While doing so, pilots will have to rely on safe taxiing at normal taxi speed.
1.2.61 To ensure
accurate manoeuvring and prevent large deviations, when nose-wheel steering or braking
effectiveness is marginal, the provision of good surface friction
characteristics is important, especially when high cross-winds are encountered.
Aircraft stand
taxilane/object separation distances
1.2.62 The preceding
apron-oriented risk aspects and functional requirements are equally valid for
separation distances between aircraft stand taxilane centre lines and objects.
1.2.63 From an operational
point of view, the separation distance as specified by the formula in terms of
a reduced gear deviation allowance and safety buffer is rated as rather
marginal relative to an operating environment where the exposure to collision
risks is normally greatest and the accuracy of aircraft manoeuvring is most
demanding. Reducing the specified values, therefore, should be considered as a
last resort only, conditional to a study scrutinizing all risk aspects discussed
in this section as applicable to the most unfavourable operating conditions
representative of the aerodrome concerned. In conducting the study,
consultation with the aircraft operator is essential to ascertain whether the
operational aircraft parameters assumed in the study are realistic.
Taxiway dimensions,
surface and shoulders
1.2.64 An
aeronautical study should further examine the level of protection provided by
existing physical layouts against run-offs from taxiway pavements. This relates
primarily to the width of taxiways and associated wheel-to-edge clearances.
Width of taxiways. The specified
wheel-to-edge clearance of 4.0 m for code letters E and F is considered a
minimum. Accordingly, the width of taxiways should provide this clearance, in
particular on curves and at intersections. As a minimum, the width of taxiways
should be equal to the sum of the wheel-to-pavement edge clearance on both
sides plus the maximum outer main gear span for the code letter.
Protection of engines
against foreign object damage
1.2.65 The degree of damage
caused to engines from ingesting foreign objects is substantial and, therefore,
a matter of continuing concern. As new larger aeroplanes are equipped with more
powerful engines, the problem is likely to be aggravated. Protection of the taxiway
shoulders extending laterally at least to the inner engine is therefore needed.
Similarly, it should be ascertained whether the type of surface of the shoulder
is adequate to resist erosion from engine blast.
1.2.66 At airports
subjected to snow and ice conditions, the problem caused by foreign object damage
is particularly critical on the entire movement area. The extent to which
snow/ice clearance is carried out will determine the risk level not only for foreign
object damage but likewise for run-offs.
Notification
1.2.67 When recommended
clearance distances are not provided at certain locations of the movement area at
a particular airport, this should be appropriately identified in the
Aerodrome/Heliport Chart - ICAO (Annex 4, Chapter 13 refers) for operational
evaluation by aircraft operators and pilots.
The
effect of new larger aeroplanes on existing airports
1.2.68 To meet the
needs of an ever-changing aviation industry, succeeding generations of larger
aeroplanes have been introduced. Experience gained through the introduction of
these aeroplanes has taught airport planners that adequate planning in the
initial design of an airport is vital. However, in spite of the best efforts of
airport planners, a facility developed for the current generation of aeroplanes
may not be adequate for succeeding generations. In order to minimize any impact
on capacity, airports would need to be expanded and developed to accommodate
such new larger aeroplanes.
1.2.69 With a view to
complying with applicable specifications, airport planners and engineers have
to explore all avenues while undertaking the rehabilitation of existing
facilities. Often, after due consideration of all options, the physical
limitations of the existing facilities may leave the airport operator with no choice
but to implement operational restrictions stemming from a compatibility study
conducted in accordance with the provisions in Annex 14, Volume I. Further
procedures outlining the compatibility between aeroplane operations and
aerodrome infrastructure and operations when an aerodrome accommodates an
aeroplane that exceeds the certificated characteristics of the aerodrome are
available in the Procedures for Air Navigation Services (PANS) - Aerodromes
(Doc 9981).
Taxiway minimum
separation distances
1.2.70 As stated in 1.2.47,
the main principle governing runway/taxiway separation distances is that the wing
tip of a taxiing aeroplane should not penetrate the strip of the associated
runway. Care must be taken to ensure that the increased wingspan of a new
larger aircraft does not increase the risk of collision with another aircraft
taxiing on a parallel taxiway if the larger aircraft inadvertently runs off a
runway, and that ILS critical and sensitive areas are protected. Where the
wingspan of an aeroplane on a taxiway penetrates the associated runway strip of
a parallel runway, appropriate operational restrictions, such as the taxiway
not being used by an aeroplane of such large wingspan when the runway is
occupied, will have to be considered. In most cases, to maintain aerodrome capacity,
simultaneous operations of smaller aeroplanes that would not infringe upon the separations
of the more demanding aeroplanes may be considered. For instance, at existing
aerodromes with runway and taxiway separation distances complying with code letter
E specifications, it may be permissible to operate a code letter E or smaller
aeroplane on the existing parallel taxiway while a code letter F aeroplane is
using the runway.
1.2.71 However, the minimum
separation distance between a runway and a parallel taxiway may not provide
adequate length for a link taxiway, connecting the parallel taxiway and the
runway, to permit safe taxiing of an aircraft behind an aircraft holding short
of the runway at the holding position due to either the larger wingspan of the
taxiing aeroplane or the fuselage length of the holding aeroplane or both. To
permit such operations, the parallel taxiway should be so located as to comply
with the requirements of Annex 14, Volume I, Tables 3-1 and 3-2, considering
the dimensions of the most demanding aeroplane in a given aerodrome code. For
example, this separation would be equal to the sum of the distance of the
runway holding position from the runway centre line, plus the overall length of
the most demanding aeroplane, and the taxiway-to-object distance specified in
column E of Table 1-1.
1.2.72 At issue is
the need to provide adequate clearances on an existing airport in order to
operate a new larger aircraft with the minimum risk possible. If the clearance
distances given Annex 14, Volume I, cannot be met, then an aeronautical study
should be conducted to ensure operational safety and to ascertain what, if any,
operational restrictions must be implemented to maintain safety (see Figure
1-6).
1.2.73 In order to
minimize such restrictions, when a new facility is planned for addition to the
existing airport infrastructure, it would be prudent to apply the basic
clearance distance concept adopted in the development of the specifications
found in Annex 14, Volume I. An example of the application of this concept
would be:
An airport with an
aerodrome reference code E is planning to develop a new link taxiway for code F
operations, adjacent to an existing code E taxiway. What should be the
separation between them?
If both taxiways are to
be used for simultaneous code F aeroplane operations (provided all other
relevant requirements are satisfactorily met) then the minimum separation distance
should be that specified for code F in Annex 14, Volume I, Table 3-1, column
10.
If the existing taxiway
is to be used by code E aircraft only, then the new code F taxiway may be
located as follows:
Minimum separation
distance: (1/2 WSe + 1/2 WSf) + C + Zf where ws is
the wing span, C is the applicable wheel-to-pavement edge clearance (4.0
m in this case) and Zf is the safety margin (7.0 m) for the most
demanding code.
In this example,
airport capacity may be slightly reduced should there be a need for two code F aeroplanes
to use these taxiways simultaneously since the existing taxiway is not in
accordance with code F specifications. Where such a philosophy is implemented
with respect to other facilities, a similar approach may be adopted, provided
the values of the wheel-to- taxiway edge clearance and wing tip clearance used
are those for the higher code letter.
Apron size and
capacity, stand clearances and taxiing on aprons
1.2.74 Larger
wingspan and the potential for greater fuselage length of code F aeroplanes
will have a direct bearing on how many of these aeroplanes can be accommodated
on existing aprons and where they can be accommodated. For codes D, E and F
aeroplanes, existing stands should provide clearances of 7.5 m as specified in
Annex 14, Volume I. Existing stands that are unable to provide such clearances
will need to be modified. Where physical constraints preclude such
modifications, operational restrictions may have to be developed to ensure safe
operations.
1.2.75 Adequate
clearances behind parked or holding aeroplanes should also be provided. This
issue is impacted not only by the wingspan of the taxiing aeroplanes but also
the fuselage length of the parked aeroplanes. While the wingspan is a defining
criterion, the fuselage length of these aeroplanes will also have a direct
bearing on their effect on other taxiing aeroplanes. Therefore, while
aeroplanes with a larger wingspan may be faced with operational restrictions
due to their wingspans, it may be also necessary to implement operational
restrictions in those cases where the increased fuselage length of an aircraft
may cause reduced clearances with other taxiing aircraft.
Figure
1-6. Taxiway to taxiway separation distances
1.3 RAPID EXIT TAXIWAYS (RETS)
General
1.3.1 A rapid exit taxiway
is a taxiway connected to a runway at an acute angle and designed to allow
landing aeroplanes to turn off at higher speeds than those achieved on other
exit taxiways, thereby minimizing runway occupancy time.
1.3.2 A decision to
design and construct a rapid exit taxiway is based upon analyses of existing
and contemplated traffic. The main purpose of these taxiways is to minimize
aircraft runway occupancy and thus increase aerodrome capacity. When the design
peak-hour traffic density is approximately less than 25 operations (landings
and take-offs), the right angle exit taxiway may suffice. The construction of
this right angle exit taxiway is less expensive, and when properly located
along the runway, achieves an efficient flow of traffic.
1.3.3 The establishment
of a single worldwide standard for the design of rapid exit taxiways has many
obvious advantages. Pilots become familiar with the configuration and can
expect the same results when landing at any aerodrome with these facilities.
Accordingly, design parameters have been established in Annex 14, Volume I, for
a grouping of exit taxiways associated with a runway whose code number is 1 or
2 and another grouping for code number 3 or 4. Since the introduction of rapid
exit taxiways, additional field tests and studies have been conducted to
determine taxiway utilization, exit taxiway location and design, and runway occupancy
time. Evaluation of such material has led to the development of exit taxiway location
and design criteria based on specified aircraft populations moving at
relatively high speeds.
1.3.4 There is some difference
of opinion with respect to the speed at which pilots negotiate rapid exit
taxiways. While it has been inferred from some studies that these taxiways are
normally used at a speed not higher than 46 km/h (25 kt) and even in some cases
at lower speeds when poor braking action or strong cross-winds are encountered,
measurements at other aerodromes have shown that they are being used at speeds
of over 92 km/h (49 kt) under dry conditions. For safety reasons 93 km/h (50 kt)
has been taken as the reference for determining curve radii and adjacent
straight portions for rapid exit taxiways where the code number is 3 or 4. For
computing the optimum exit locations along the runway, however, the planner
will choose a lower speed. In any case, the optimum utilization of rapid exits
requires pilot cooperation. Instruction on the design of, and benefits to be
obtained from use of, these taxiways may increase their use.
Location
and number of exit taxiways
Planning criteria
1.3.5 The following
basic planning criteria should be considered when planning rapid exit taxiways
to ensure that, wherever possible, standard design methods and configurations
are used:
a) for runways
exclusively intended for landings, a rapid exit taxiway should be provided only
if dictated by the need for reduced runway occupancy times consistent with
minimum inter-arrival spacings;
b) for runways where alternating
landings and departures are conducted, time separation between the landing
aircraft and the following departing aircraft is the main factor limiting
runway capacity;
c) as different types of
aircraft require different locations for rapid exit taxiways, the expected
aircraft fleet mix will be an essential criterion; and
d) the threshold speed,
braking ability and operational turn-off speed (Vex) of the aircraft will determine
the location of the exits.
1.3.6 The location of
exit taxiways in relation to aircraft operational characteristics is determined
by the deceleration rate of the aircraft after crossing the threshold. To
determine the distance from the threshold, the following basic conditions
should be taken into account:
a) threshold speed; and
b) initial exit speed or
turn-off speed at the point of tangency of the central (exit) curve (point A,
Figures 1-7 and 1-8).
Figure
1-7. Design for rapid exit taxiways (code number 1 or 2)
Figure
1-8. Design for rapid exit taxiways (code number 3 or 4)
Design, location and
number of rapid exit taxiways
1.3.7 Determining the
optimum location and required number of rapid exit taxiways to suit a
particular group of aeroplanes is recognized as a comparatively complex task
owing to the many criteria involved. Although most of the operational
parameters are specific to the type of aircraft with respect to the landing
manoeuvre and subsequent braked deceleration, there are some criteria which are
reasonably independent of the type of aircraft.
1.3.8 Accordingly, a
methodology, known as the Three Segment Method, was developed which permits the
determination of the typical segmental distance requirements from the landing
threshold to the turn-off point based on the operating practices of individual
aircraft and the effect of the specific parameters involved. The methodology is
based on analytical considerations supplemented by empirical assumptions, as
described below.
1.3.9 For the purpose
of exit taxiway design, the aircraft are assumed to cross the threshold at an average
of times the stall speed in the landing configuration at maximum certificated landing
mass with an average gross landing mass of about 85 per cent of the maximum. Further,
aircraft can be grouped on the basis of their threshold speed at sea level as
follows:
Group A - less than
169 km/h (91 kt)
Group B - between 169
km/h (91 kt) and 222 km/h (120 kt)
Group C - between 224
km/h (121 kt) and 259 km/h (140 kt)
Group D - between 261
km/h (141 kt) and 306 km/h (165 kt), although the maximum threshold crossing
speed of aircraft currently in production is 282 km/h (152 kt).
1.3.10 An analysis of
some aircraft indicates that they may be placed in the groups as follows:
Group A
|
Group B
|
DC3
DHC6
DHC7
|
Avro RJ 100
DC6
DC7
Fokker F27
Fokker F28
HS146
HS748
IL76
|
Group C
|
Group D
|
A300, A310, A320,
A330, A359, A388
|
A340
|
B707-320
|
A351
|
B727
|
B747
|
B737
|
B777
|
B747-SP
|
B779
|
B757
|
B789
|
B767
|
DC10-30/40
|
B788
|
MD-11
|
DC9
|
IL62
|
MD80
|
IL86
|
MD90
|
IL96
|
DC10-10
|
L1011-500
|
L1011-200
|
TU154
|
1.3.11 The number of
exit taxiways will depend on the types of aircraft and number of each type that
operate during the peak period. For example, at a very large aerodrome, most
aircraft will likely be in groups C or D. If so, only two exits may be
required. On the other hand, an aerodrome having a balanced mixture of all four
groups of aircraft may require four exits.
1.3.12 Using the Three
Segment Method, the total distance required from the landing threshold to the
point of turn-off from the runway centre line can be determined according to
the method illustrated in Figure 1-9.
The total distance S
is the sum of three distinct segments which are computed separately.
Segment 1: Distance
required from landing threshold to maingear touchdown (S1).
Segment 2: Distance
required for transition from maingear touchdown to establish stabilized braking
configuration (S2).
Segment 3: Distance
required for deceleration in a normal braking mode to a nominal turn-off speed
(S3).
Speed profile:
Vth
|
Threshold speed
based on 1.3 times the stall speed of assumed landing mass equal to 85 per
cent of maximum landing mass. Speed is corrected for elevation and airport
reference temperature.
|
Vtd
|
Assumed as Vth - 5
kt (conservative). Speed decay considered representative for most types of
aircraft.
|
Vba
|
Assumed brake
application speed.
|
Vth
|
- 15 kt (wheel
brakes and/or reverse thrust application).
|
Vex
|
Nominal turn-off
speed:
Code number 3 or 4:
30 kt
Code number 1 or 2:
15 kt
|
for standard rapid
exit taxiways according to Figures 1-7 and 1-8.
Figure
1-9. Three Segment Method
For other types of
exit taxiways see Table 1-8 and Figure 1-10 for turn-off speed.
Distances [in m]:
S1
|
Empirically derived
firm distance to mean touchdown point, corrected for downhill slope and
tailwind component where applicable.
|
|
Aircraft category C
and D:
|
S1 = 450 m
|
|
Correction for
slope:
|
+ 50 m / - 0.25%
|
|
Correction for
tailwind:
|
+ 50 m / + 5 kt
|
|
Aircraft category A
and B:
|
S1 = 250 m
|
|
Correction for
slope:
|
+ 30 m / - 0.25%
|
|
Correction for
tailwind:
|
+ 30 m / + 5 kt
|
S2
|
The transition
distance is calculated for an assumed transition time (empirical) Dt = 10
seconds at an average ground speed of:
|
|
s2 = 10 x Vav [ Vav in m/s], or
s2 = 5 x (Vth -10) [ Vth in kt]
|
|
S3
|
The braking
distance is determined based on an assumed deceleration rate ‘a’ according to
the following equation:
A deceleration rate
of a = 1.5 m/s2 is
considered a realistic operational value for braking on wet runway surfaces.
|
1.3.13 The final selection
of the most practical rapid exit taxiway location(s) must be considered in the
overall planning requirements, taking into account other factors such as:
- location of the
terminal/apron area;
- location of other
runways and their exits;
- optimization of
traffic flow within the taxiway system with respect to traffic control
procedures;
- avoidance of
unnecessary taxi detours, etc.
Furthermore, there may
be a need to provide additional exit taxiways - especially at long runways - after
the main rapid exit(s) depending upon local conditions and requirements. These
additional taxiways may or may not be rapid exit taxiways. Intervals of
approximately 450 m are recommended up to within 600 m of the end of the
runway.
Table
1-8. Aircraft speed versus the radius of a rapid exit taxiway
Radii
R [m]:
|
Vdes
[kt]:
|
Vop [kt]:
|
40
|
14
|
3
|
60
|
17
|
16
|
120
|
24
|
22
|
160
|
28
|
24
|
240
|
34
|
27
|
375
|
43
|
30
|
550
|
52
|
33
|
Based on the design
exit speed Vdes
complying
with a lateral acceleration of 0.133 g, the operational turn- off speed Vop is determined
empirically to serve as the criterion for the optimal location of the exit.
Figure
1-10. Aircraft speed versus the radius of a rapid exit taxiway
1.3.14 Some aerodromes
have heavy activity of aircraft in code number 1 or 2. When possible, it may be
desirable to accommodate these aircraft on an exclusive runway with a rapid exit
taxiway. At those aerodromes where these aircraft use the same runway as
commercial air transport operations, it may be advisable to include a rapid
exit taxiway to expedite ground movement of the small aircraft. In either case,
it is recommended that this exit taxiway be located at 450 m to 600 m from the
threshold.
1.3.15 As a result of
Recommendation 3/5 framed by the Aerodromes, Air Routes and Ground Aids
Divisional Meeting (1981), ICAO in 1982 compiled data on actual rapid exit
taxiway usage. The data, which were collected from 72 airports and represented
operations on 229 runway headings, provided information on the type of exit taxiway,
distances from threshold to exits, exit angle and taxiway usage for each runway
heading. During the analysis it was assumed that the sample size of the
surveyed data was equal for each runway heading. Another assumption was that
whenever an aircraft exited through an exit taxiway located at an angle larger
than 45°, the aircraft could have exited through a rapid exit taxiway, had
there been a rapid exit taxiway on that location (except the runway end). The
accumulated rapid exit usage versus distance from thresholds is tabulated in
Table 1-9. This means that had there been a rapid exit taxiway located at a
distance of 2200 m from thresholds, 95 per cent of aircraft in group A could
have exited through that exit taxiway. Similarly, rapid exit taxiways located
at 2300 m, 2670 m and 2950 m from thresholds could have been utilized by 95 per
cent of aircraft in groups B, C and D, respectively. The table shows the
distances as corrected by using the correction factors suggested in the study carried
out by the Secretariat and presented to the AGA/81 Meeting, namely, 3 per cent
were 300 m of altitude and 1 per cent per 5.6°C above 15°C.
Table
1-9. Accumulated rapid exit usage by distance from threshold (metres)
Aircraft
category
|
50%
|
60%
|
70%
|
80%
|
90%
|
95%
|
100%
|
A
|
1
170
|
1
320
|
1
440
|
1
600
|
1
950
|
2
200
|
2
900
|
B
|
1
370
|
1
480
|
1
590
|
1
770
|
2
070
|
2
300
|
3
000
|
C
|
1
740
|
1
850
|
1
970
|
2
150
|
2
340
|
2
670
|
3
100
|
D
|
2
040
|
2
190
|
2
290
|
2
480
|
2
750
|
2
950
|
4
000
|
Geometric
design
1.3.16 Figures 1-7 and
1-8 present some typical designs for rapid exit taxiways in accordance with the
specifications given in Annex 14, Volume I. For runways of code number 3 or 4,
the taxiway centre line marking begins at least 60 m from the point of tangency
of the central (exit) curve and is offset 0.9 m to facilitate pilot recognition
of the beginning of the curve. For runways of code number 1 or 2, the taxiway
centre line marking begins at least 30 m from the point of tangency of the
central (exit) curve.
1.3.17 A rapid exit
taxiway should be designed with a radius of turn-off curve of at least:
550 m where the code
number is 3 or 4, and
275 m where the code
number is 1 or 2;
to enable exit speeds
under wet conditions of:
93 km/h (50 kt) where
the code number is 3 or 4, and
65 km/h (35 kt) where
the code number is 1 or 2.
1.3.18 The radius of
the fillet on the inside of the curve at a rapid exit taxiway should be
sufficient to provide a widened taxiway throat in order to facilitate
recognition of the entrance and turn-off onto the taxiway.
1.3.19 A rapid exit taxiway
should include a straight distance after the turn-off curve sufficient for an
exiting aircraft to come to a full stop clear of any intersecting taxiway and
should not be less than the following when the intersection angle is 30°:
Code
number
|
Code
number
|
1
or 2
|
3
or 4
|
35
m
|
75
m
|
The above distances
are based on deceleration rates of 0.76 m/s2 along the turn-off
curve and 1.52 m/s2 along the straight section.
1.3.20 The
intersection angle of a rapid exit taxiway with the runway should not be
greater than 45° nor less than 25° and preferably should be 30°.
1.4 TAXIWAYS ON BRIDGES
General
1.4.1 The layout of an
aerodrome, its dimensions and/or the extension of its runway/taxiway system may
require taxiways to bridge over surface transport modes (roads, railways,
canals) or open water (rivers, sea bays). Taxiway bridges should be designed so
as not to impose any difficulties for taxiing aircraft and to permit easy
access to emergency vehicles responding to an emergency involving an aircraft
on the bridge. Strength, dimensions, grades and clearances should allow
unconstrained aircraft operations day and night as well as under varying seasonal
conditions, i.e. heavy rain, periods of snow and ice coverage, low visibility or
gusty winds. The requirements of taxiway maintenance, cleaning and snow
removal, as well as emergency evacuation of the aircraft occupants, should be taken
into account when bridges are being designed.
Siting
1.4.2 For operational
and economic reasons the number of bridging structures required and problems
related therewith can be minimized by applying the following guidelines:
a) if possible, the surface
modes should be routed so that the least number of runways or taxiways will be
affected;
b) the surface modes
should be concentrated so that preferably all can be bridged with a single
structure;
c) a bridge should be
located on a straight portion of a taxiway with a straight portion provided on
both ends of the bridge to facilitate the alignment of the aeroplanes
approaching the bridge;
d) rapid exit
taxiways should not be located on a bridge; and
e) bridge locations
that could have an adverse effect upon the instrument landing system, the approach
lighting or runway/taxiway lighting systems should be avoided.
Dimensions
1.4.3 The design of
the bridge structure is determined by its purpose and the specifications
relevant to the transport mode that it will serve. Aeronautical requirements
should be met with respect to width, shoulders and gradings, etc., of the
taxiway.
1.4.4 The bridge
width measured perpendicularly to the taxiway centre line shall not be less
than the width of the graded portion of the strip provided for that taxiway,
unless a proven method of lateral restraint is provided which shall not be
hazardous for aeroplanes for which the taxiway is intended. Therefore, minimum
width requirements will normally be:
20.5 m
|
where the code
letter is
|
A
|
22m
|
wherethecodeletter
is
|
B
|
25m
|
wherethecodeletter
is
|
C
|
37m
|
wherethecodeletter
is
|
D
|
38m
|
wherethecodeletter
is
|
E
|
44m
|
wherethecodeletter
is
|
F
|
with the taxiway in
the centre of the strip. In the exceptional cases when a curved taxiway has to be
located on the bridge, extra width should be provided to compensate for the
unsymmetrical movement of the aircraft by track-in of the main gear.
1.4.5 If the type of
aircraft using the aerodrome is not clearly defined or if the aerodrome is
limited by other physical characteristics, the width of the bridge to be
designed should be related to a higher code letter from the very beginning. This
will prevent the aerodrome operator from taking very costly corrective action
once a larger aircraft starts to operate on that aerodrome and has to use the
taxiway bridge.
1.4.6 The taxiway
width on the bridge should be at least as wide as off the bridge. Unlike the construction
of other parts of the taxiway system, the strip on the bridge will normally
have a paved surface and serve as a fully bearing shoulder. Additionally, the
paved strip on the bridge facilitates maintenance and, where necessary, snow
clearing work. Furthermore, the paved surface strip provides access to the
bridge for rescue and fire fighting vehicles as well as other emergency
vehicles.
1.4.7 The efficiency
of ground movement operations will be enhanced if aircraft are able to approach
and depart from bridges on straight portions of the taxiway. These will enable
aircraft to align themselves with the main undercarriage astride the taxiway
centre line before crossing the taxiway bridge. The length of the straight
section should be at least twice the wheel base (distance from the nose gear to
the geometric centre of the main gear) of the most demanding aircraft and not
less than
15m for codeletter A
20m for codeletter B
50m for codeletter C,
D or E
70m for codeletter F.
It should be noted that
possible future aircraft may have a wheel base of 35 m or more indicating a
requirement for a straight distance of at least 70 m.
Gradients
1.1.8 For drainage
purposes, taxiway bridges are generally designed with normal taxiway transverse
slopes. If, for other reasons, a slope less than 1.5 per cent has been selected,
consideration should be given to the provision of sufficient drainage
capability on the taxiway bridge.
1.1.9 Ideally, the
bridge should be level with the adjacent aerodrome terrain. If, for other technical
reasons, the top of the bridge must be higher than the surrounding aerodrome
terrain, the adjoining taxiway sections should be designed with slopes which do
not exceed the longitudinal gradients specified in Table 1-1.
Bearing
strength
1.1.10 A taxiway bridge
should be designed to support the static and dynamic loads imposed by the most demanding
aircraft expected to use the aerodrome. Future trends of aircraft mass
development should be taken into account in specifying the “most demanding
aircraft”. Information on future trends is regularly issued by the
manufacturers’ associations. Incorporation of future requirements may help to avoid
costly redesign of bridges due to progress in technology and/or increasing
transport demand.
1.1.11 The strength
of the bridge should normally be sufficient over the entire width of the graded
area of taxiway strip to withstand the traffic of the aeroplanes the taxiway is
intended to serve. Minimum width requirements are specified in 1.4.4. Parts of
the same bridge that have been added to serve vehicular traffic only may have
lesser strength than those intended for aircraft traffic.
Lateral
restraint
1.1.12 When the full
load-bearing width provided is less than that of the graded area of the taxiway
strip, a proven method of lateral restraint should be provided that shall not be
hazardous to aeroplanes for which the taxiway is intended. The lateral
restraint system should be provided at the edges of the full load-bearing
portion of the strip to prevent the aircraft from falling off the bridge or
entering areas of reduced bearing strength. Lateral restraint devices should
generally be considered as additional safety measures rather than a means of
reducing the full load-bearing width of the taxiway bridge.
1.1.13 Information collected
from States indicates that lateral restraint devices are normally provided on a
taxiway bridge, irrespective of the width of the full load-bearing area. The
lateral restraint device generally consists of a concrete curb which may serve
as a barrier. Two examples of concrete curbs commonly used are shown in Figure
1-11. The recommended minimum distance for the location of the lateral
restraint device varies among States, but a range between 9 and 27 m from the taxiway
centre line was reported. However, factors mentioned in 1.4.6 should be kept in
view when considering the location of lateral restraints. The curb is generally
from 20 to 60 cm high, the lowest type of curb being used when the width of the
graded area is significantly greater than the width of the taxiway strip.
Taxiway bridges have been in service for varying periods of time, some of them
for over 20 years, and no occurrences of aircraft running off taxiway bridges
have been reported.
1.1.14 It may be
desirable to provide a second lateral restraint device. This device may consist
of a concrete curb or a safety guard rail which is not designed to prevent aircraft
running off the taxiway but rather as a safety measure for maintenance
personnel and vehicles using the bridge.
Figure
1-11. Examples of concrete curbs
Blast
protection
1.1.15 Where the
taxiway passes over another transport mode, some kind of protection against
aircraft engine blast may need to be provided. This can be accomplished by
light cover construction of perforated material (bars or grid-type elements)
capable of braking the initial jet blast to uncritical velocities of the order
of 56 km/h. Contrary to closed covers, an open construction does not cause any
drainage and loading capacity problems.
1.1.16 The overall width
of the bridge and protected area should be equal to or exceed the blast pattern
of the aircraft using the taxiway. This may be determined by reference to the
manufacturers’ literature on the aircraft concerned.
1.5 FILLETS
General
1.5.1 Annex 14, Volume
I, recommends minimum clearance distances between the outer main wheels of the
aircraft which the taxiway is intended to serve and the edge of the taxiway
when the cockpit of the aircraft remains over the taxiway centre line markings.
These clearance distances are shown in Table 1-1. To meet these requirements
when an aircraft is negotiating a turn, it may be necessary to provide
additional pavement on taxiway curves and at taxiway junctions and
intersections. It is to be noted that in the case of a taxiway curve the extra
taxiway area provided to meet the recommended clearance distance requirement is
part of the taxiway and therefore the term “extra taxiway width” is used rather
than “fillet”. In the case of a junction or intersection of a taxiway with a runway,
apron or another taxiway, however, the term “fillet” is considered to be the
appropriate term. In both cases (the extra taxiway width as well as the
fillet), the strength of the extra paved surface to be provided should be the
same as that of the taxiway. The following material presents concise
information on fillet design.
Methods
for manoeuvring aircraft on taxiway intersections
1.5.2 Specifications
in Annex 14, Volume I concerning taxiway design as well as relevant visual aids
specifications are based upon the concept that the cockpit of the aircraft
remains over the taxiway centre line. Offsetting the guidelines outwards should
be avoided because it implies having a separate guideline for each aircraft
type and for use in both directions. Such a multiplicity of lines is
impractical particularly when the taxiway is intended to be used at night or during
poor visibility conditions, and it would thus be necessary to provide a
compromise offset guideline that could be used by all aircraft.
1.6 TAXIWAY SHOULDERS AND STRIPS
General
1.6.1 A shoulder is an
area adjacent to the edge of a full strength paved surface so prepared as to
provide a transition between the full strength pavement and the adjacent
surface. The main purpose of the provision of a taxiway shoulder is: to prevent
jet engines that overhang the edge of a taxiway from ingesting stones or other
objects that might damage the engine; to prevent erosion of the area adjacent
to the taxiway; and to provide a surface for the occasional passage of aircraft
wheels. A shoulder should be capable of withstanding the wheel loading of the heaviest
airport emergency vehicle. A taxiway strip is an area, including a taxiway,
intended to protect an aircraft operating on the taxiway and to reduce the risk
of damage to an aircraft accidentally running off the taxiway.
1.6.2 The widths to
be provided for taxiway shoulders and strips are given in Table 1-1. It may be
noted that shoulders 5.5 m wide for code letter D, 7.5 m wide for code letter E
and 10.5 m wide for code letter F on both sides of the taxiway are considered
to be suitable. These taxiway shoulder width requirements are based on the most
critical aircraft operating in these categories, at this time. On existing airports,
it is desirable to protect a wider area should operations by new larger
aircraft be intended, as the possibility of potential foreign object damage and
the effect of exhaust blast on the taxiway shoulder during break away will be
higher. The taxiway shoulder width is considered suitable when it protects the
inboard engines of the critical aircraft which are much closer to the ground
than the outboard engines.
1.6.3 The graded portions
to be provided for taxiways are based on the maximum OMGWS of a group and on
the deviation of one aircraft from the taxiway centre line (wheel- to-edge
clearance) and the increment (Z), but in any case not lower than the
required shoulder width as shown in Table 1-1.
1.6.4 The surface of
the shoulder that abuts the taxiway should be flush with the surface of the
taxiway while the surface of the strip should be flush with the edge of the
taxiway or shoulder, if provided. For code letter C, D, E or F, the graded
portion of the taxiway strip should not rise more than 2.5 per cent or slope
down at a gradient exceeding 5 per cent. The respective slopes for code letter
A or B are 3 per cent and 5 per cent. The upward slope is measured with reference
to the transverse slope of the adjacent taxiway surface and the downward slope
is measured with reference to the horizontal. There should, furthermore, be no
holes or ditches tolerated within the graded portion of the taxiway strip. The
taxiway strip should provide an area clear of objects which may endanger
taxiing aeroplanes. Consideration will have to be given to the location and
design of drains on a taxiway strip to prevent damage to an aircraft accidentally
running off a taxiway. Suitably designed drain covers may be required.
1.6.5 No obstacles should
be allowed on either side of a taxiway within the distance shown in Table 1 -1.
However, signs and any other objects which, because of their functions, must be
maintained within the taxiway strip in order to meet air navigation
requirements may remain but they should be frangible and sited in such a manner
as to reduce to a minimum the hazard to an aircraft striking them. Such objects
should be sited so that they cannot be struck by propellers, engine pods and
wings of aircraft using the taxiway. As a guide they should be so sited that
there is nothing higher than 30 cm above taxiway edge level within the taxiway
strip.
Treatment
1.6.6 Taxiway shoulders
and graded portions of strips provide an obstacle-free area intended to
minimize the probability of damage to an aircraft using these areas
accidentally or in an emergency. These areas should thus be prepared or
constructed so as to reduce the risk of damage to an aircraft running off the
taxiway and be capable of supporting access by rescue and fire fighting
vehicles and other ground vehicles, as appropriate, over its entire area. When
a taxiway is intended to be used by turbine-engined aircraft, the jet engines
may overhang the edge of the taxiway while the aircraft is taxiing and may then
ingest stones or foreign objects from the shoulders. Further, blast from the
engines may impinge on the surface adjacent to the taxiway and may dislodge
material with consequent hazard to personnel, aircraft and facilities. Certain
precautions must therefore be taken to reduce these possibilities. The type of
surface of the taxiway shoulder will depend on local conditions and
contemplated methods and cost of maintenance. While a natural surface (e.g.
turf) may suffice in certain cases, in others, an artificial surface may be
required. In any event, the type of surface selected should be such as to avoid
the blowing up of debris as well as dust while also meeting the minimum load
bearing capability mentioned above.
1.6.7 Under most
taxiing conditions, blast velocities are not critical except at intersections
where thrusts approach those on breakaway. With the present criteria of up to
23 m wide taxiways, the outboard engines of the larger jets extend beyond the
edge of the pavement. For this reason, treatment of taxiway shoulders is
recommended to prevent their erosion and to prevent the ingestion of foreign
material into jet engines or the blowing of such material into the engines of
following aircraft. The material below presents concise information on methods
of protection of marginal areas subject to blast erosion and of those areas
which must be kept free from debris to prevent ingestion by overhanging turbine
engines. Additional information can be found in Appendix 2, 15 to 18.
1.6.8 Studies of engine
blast and blast effects have included profile development and velocity contour
as related to engine type, aircraft mass and configuration; variation in
thrust; and effect of cross-wind. It has been found that the effects of heat
associated with the jet wake are negligible. Heat dissipates more rapidly with distance
than blast force. Furthermore, personnel, equipment and structures normally do
not occupy the upper limits of those areas where heat is generated during jet
operations. Studies indicate that objects in the path of a jet blast are acted upon
by several forces including the dynamic pressure associated with the impact of
gases as they strike the surface, drag forces set up when viscous gases move
past an object, and uplift forces caused by either differential pressures or
turbulence.
1.6.9 Cohesive soils,
when loosened, are susceptible to erosion by jet blast. For these soils, protection
that is adequate against the natural erosive forces of wind and rain will
normally be satisfactory. The protection must be a kind that adheres to the
clay surfacing so that the jet blast does not strip it off. Oiling or chemical
treatment of a cohesive soil surface are possible solutions. The cohesion
required to protect a surface from blast erosion is small; normally, a plasticity
index (PI) of two or greater will suffice. However, if the area is periodically
used by ground vehicles with their equipment, a PI of six or more will be
necessary. There should be good surface drainage for these areas if equipment
moves over them since this type of surface will be softened by ponding. Special
consideration must be given to highly plastic cohesive soils subject to more
than about a 5 per cent shrinkage. For these soils, good drainage is very
important since they become extremely soft when wet. When dry, these soils
crack and become subject to greater lift forces. Fine, cohesionless soils,
which are the most susceptible to erosion by blast, are considered to be those
which do not have the cohesive properties defined above.
Shoulder and blast
pad design thickness
1.6.10 The thickness
of taxiway shoulders and blast pads should be able to accommodate an occasional
passage of the critical aircraft considered in pavement design and the critical
axle load of emergency or maintenance vehicles which may pass over the area. In
addition, the following factors should be taken into account:
a) The minimum design
thickness required for shoulder and blast pads to accommodate the critical
aircraft can be taken as one half of the total thickness required for the
adjacent paved area;
b) the critical axle
load of the heaviest emergency or maintenance vehicle likely to traverse the area
should be considered in the determination of the pavement thickness. If this
thickness is greater than that based on a) above, then this design thickness
should be used for shoulder and blast pads;
c) for wide-body aircraft
such as the A330, A340, A350, B767, B777, B787, MD11, L1011 or smaller, the recommended
minimum surface thickness, if bituminous concrete on an aggregate base is used,
is 5 cm on shoulders and 7.5 cm on blast pads. For aircraft such as the B747 or
larger, an increase of 2.5 cm in this thickness is recommended;
d) the use of a
stabilized base for shoulders and blast pads is also recommended. A 5 cm bituminous
concrete surface is the recommended minimum on a stabilized base;
e) the use of
Portland cement concrete and a granular sub-base for shoulder and blast pads
(or cement- stabilized sand) is advantageous. A minimum thickness of 15 cm of
cement concrete is recommended; and
f) the same compaction
and construction criteria for sub-grade and pavement courses in shoulder and
blast areas should be used as for full strength pavement areas. It is
recommended that a drop-off of approximately 2.5 cm be used at the edge of the
full strength pavement, shoulders and blast pads to provide a definite line of
demarcation.
1.7 FUTURE AIRCRAFT DEVELOPMENTS
General
1.7.1 Annex 14,
Volume I sets forth the minimum aerodrome specifications for aircraft that have
the characteristics of those which are currently operating or for similar
aircraft that are planned for introduction in the immediate future. The current
specifications are therefore intended to accommodate aeroplanes with wing spans
of up to 80 m, e.g. Airbus A380-800. Accordingly, any additional safeguards
that might be considered appropriate to provide for more demanding aircraft are
not taken into account in the Annex. Such matters are left to appropriate authorities
to evaluate and take into account as necessary for each particular aerodrome.
1.7.2 The following
information may assist these authorities and airport planners to be aware of the
way in which the introduction of larger aircraft may alter some of the
specifications. In this respect, it is worth noting that it is probable that
some increase in current maximum aircraft size may be acceptable without major
modifications to existing aerodromes. However, the upper limit of aircraft size
which is examined below is, in all probability, beyond this consideration unless
aerodrome procedures are altered, with resulting reduction in aerodrome capacity.
Future
aircraft trends
1.7.3 The trends for future
aircraft designs may be obtained from various sources, including the aircraft
manufacturers and the International Coordinating Council of Aerospace
Industries Associations. For the purpose of planning future airport
development, the following aircraft dimensions may be used:
|
Code F
|
Larger than code F
|
wing span
|
up to 80 m
|
up to 90 m
|
outer main gear
wheel span
|
up to 15 m
|
up to 15 m
|
overall length
|
up to 80 m
|
80 m or more
|
tail height
|
up to 24 m
|
up to 24 m
|
maximum gross mass
|
575 000 kg or more
|
650 000 kg or more
|
Aerodrome
data
1.7.4 Using the
rationale developed for implementation of certain specifications related to the
aerodrome reference code, it is possible that aircraft with the dimensions
shown in the previous paragraph could have the effects on the taxiway system
described below.
Taxiway
width
1.7.5 It is expected
that taxiing characteristics of future large aircraft will be similar to those
of the largest current aircraft when considering the straight portion of the
taxiway. The taxiway width, WT, for these aircraft is represented by the
relationship:
WT = TM + 2C
where:
TM = maximum outer main
gear wheel span
C = clearance between the
outer main gear wheel and the taxiway edge (maximum allowable lateral
deviation). This geometry is shown in Figure 1-12.
1.7.6 Assuming the
expected growth of outer main gear wheel span to 15 m and a wheel- to-edge
clearance of 4.0 m, the taxiway width for planning purposes comes to 23 m.
Figure
1-12. Taxiway width geometry
Runway-parallel
taxiway separation distance
1.7.7 The separation
distance between a runway and a parallel taxiway is currently based on the
premise that any part of the aircraft on the taxiway centre line must not
protrude into the associated runway strip area. This distance, S, is
represented by the relationship:
where:
SW = strip width
WS = wing span
This geometry is
illustrated in Figure 1-13.
1.7.8 The separation
distance for planning purposes for the largest aircraft predicted by future trends
data is m. This value is based on the assumption that this aircraft, having a
wing span of 90 m, can safely operate in the current 280 m runway strip width
required for a non-precision or precision approach runway.
Figure
1-13. Parallel runway-taxiway separation geometry
Separation
between parallel taxiways
1.7.9 The rationale
for determining the separation distance between parallel taxiways, one of which
may be an apron taxiway, is based on providing a suitable wing tip clearance
when an aircraft has deviated from the taxiway centre line. Primary factors
influencing this issue are: wing span (WS), main gear wheel clearance (C)
and wing tip clearance (Z). This results in an expression for the
separation distance, S, of:
S = WS + C + Z
where:
WS = wing span
C = clearance between
the outer main gear wheel and the taxiway edge (maximum allowable lateral
deviation)
Z = wing tip clearance
(increment) that accounts for aircraft steering performance, pavement surface conditions,
and an assured safety buffer to account for unforeseen problems, and to
minimize potential adverse impacts on airport capacity.
The geometry of this
relationship is shown in Figure 1-14.
1.7.10 The separation
distances between parallel taxiways and between parallel taxiways and apron taxiways
are considered to be the same since it is assumed that the speed that the aircraft
will taxi in both systems is the same. The separation distance, for planning
purposes, for a future aircraft span of 90 m, a lateral deviation, C, of
4.0 m and a current code F wing tip clearance (increment) of 7.0 m, is 101 m.
Figure
1-14. Parallel taxiway separation geometry
Separation
distance between taxiway and object
1.7.11 Taxiing speeds
on a taxiway and on an apron taxiway are assumed to be the same. Therefore, the
separation distances to an object are assumed to be the same in both cases. A
rationale has been developed which bases the taxiway-to-object separation distance
on a clearance between the wing tip of the aircraft and the object when the
aircraft has deviated from the taxiway centre line. This taxiway-to-object
separation distance, S, is:
where:
WS = wing span
C = clearance between
the outer main gear wheel and the taxiway edge (maximum allowable lateral
deviation)
Z = wing tip clearance
to an object (increment); (see explanation above in 1.7.9).
Figure 1-15
illustrates this geometry.
1.7.12 Application of
the above relationship results in a taxiway centre line or apron taxiway centre
line-to-object distance of 53 m when using a 4.0 m deviation and a current code
F wing tip clearance (increment) of 7.0 m. The assumed wing span is 84 m.
Aircraft
stand taxilane-to-object
1.7.13 The lower
taxiing speed of an aircraft in a stand taxilane permits a smaller lateral
deviation to be considered than with other taxiways. The geometry of Figure
1-16 illustrates the relationship of aircraft clearance to an object in a stand
taxilane. Thus the separation distance, S, is found using the following
formula:
where:
WS = wing span
d = lateral deviation
Z = wing tip clearance
to an object (increment); (see explanation in 1.7.9 above).
1.7.14 Application of
the above rationale results in an object separation distance, for planning
purposes, for future large aircraft in a stand taxilane of 52.5 m. This value
is based on a wing span of 90 m, a gear deviation of 3.5 m and a wing tip
clearance (increment) of 5.0 m.
Figure
1-16. Aircraft stand taxilane-to-object geometry
Other
considerations
1.7.15 In addition to
the guidance in the preceding paragraphs, preliminary criteria to accommodate
future aircraft development are described below:
Runway width: 45 m
Runway sight
distance: Same
as current requirement for code letter F
Runway transverse
slope: Same
as current requirement for code letter F
Runway shoulders: Overall width of runway
and shoulder - 75 m, paved to a minimum overall width of runway and shoulder of
not less than 60 m. A widened area may need to be prepared to prevent erosion
of the adjacent area and foreign object damage.
Slope and strength of
runway shoulders: Same
as current requirement for code letter F
Minimum separation
distances between taxiway centre line and runway centre line:
1/2 wing span (Y)
|
45 m
|
+
1/2 strip width
|
|
(non-instrument
approach runway)
|
75 m
|
Total
|
120 m
|
or
|
|
1/2 wing span (Y)
|
45 m
|
+
1/2 strip width
|
|
(instrument
approach runway)
|
140 m
|
Total
|
185 m
|
Taxiway pavement and shoulder
(overall width): Adequate
space should be prepared to prevent erosion of the adjacent area and foreign
object damage. The width of that portion of a taxiway bridge capable of
supporting aeroplanes shall not be less than the width of the graded area of
the strip provided for that taxiway.
Graded portion of
taxiway strip (overall width): Adequate space should be prepared to prevent
erosion of the adjacent area and foreign object damage. The width of that
portion of a taxiway bridge capable of supporting aeroplanes shall not be less
than the width of the graded area of the strip provided for that taxiway
CHAPTER 2
HOLDING BAYS AND OTHER BYPASSES
2.1
NEED FOR HOLDING BAYS AND OTHER BYPASSES
2.1.1 Procedures for
Air Navigation Services - Air Traffic Management (Doc 4444), Chapter 7,
7.9.1, Departure sequence, states that “departures shall normally be cleared in
the order in which they are ready for take-off, except that deviations may be
made from this order of priority to facilitate the maximum number of departures
with the least average delay”. At low levels of aerodrome activity (less than
approximately 50 000 annual operations), there is normally little need to make
deviations in the departure sequence. However, for higher activity levels, aerodromes
with single taxiways and no holding bays or other bypasses provide aerodrome
control units with no opportunity to change the sequence of departures once the
aircraft have left the apron. In particular, at aerodromes with large apron
areas, it is often difficult to arrange for aircraft to leave the apron in such
a way that they will arrive at the end of the runway in the sequence required
by air traffic services units.
2.1.2 The provision
of an adequate number of holding bay spaces or other bypasses, based upon an
analysis of the current and near-term hourly aircraft departure demand, will
allow a large degree of flexibility in generating the departure sequence. This provides
air traffic services units with greater flexibility in adjusting the take-off
sequence to overcome undue delays, thus increasing the capacity of an aerodrome.
In addition, holding bays or other bypasses allow:
a) departure of
certain aircraft to be delayed owing to unforeseen circumstances without
delaying the following aircraft (for instance, a last minute addition to the
payload or a replacement of defective equipment);
b) aircraft to carry
out pre-flight altimeter checks and alignment and programming of airborne
inertial navigation systems when this is not possible on the apron;
c) engine runups for
piston aircraft; and
d) establishment of a
VOR aerodrome check-point.
2.2 TYPES OF BYPASSES
2.2.1 In general,
taxiway features that allow an aircraft to bypass a preceding aircraft can be
divided into three types:
a) Holding bays.
A defined area where aircraft can be held or bypassed. Figure 2-
1 shows some examples
of holding bay configurations and Figure 2-2 gives a detailed example of a
holding bay, located at the taxi-holding position.
b) Dual taxiways.
A second taxiway or a taxiway bypass to the normal parallel taxiway. Figure 2-3
shows some examples.
c) Dual runway
entrances. A duplication of the taxiway entrance to the runway. Some
examples are shown in Figure 2-4.
Figure
2-1. Examples of holding bay configurations
Figure
2-2. Detailed example of holding bay
Figure 2-3. Examples
of dual taxiways
Figure
2-4. Examples of dual runway entrances
2.2.2 If a holding
bay is used, aircraft can, on the basis of their priority, take off in the
order as cleared by ATC. The availability of a holding bay allows aircraft to leave
and independently re-enter the departure stream. A detailed example of the
pavement area for a holding bay located at the taxi-holding position is shown
in Figure 2-2. This design is for a non-precision or a precision approach runway
where the code number is 3 or 4 and incorporates an aircraft wing-
tip-to-wing-tip clearance of 15 m when both aircraft are centred on the centre
line. Holding bay design for other runway types or locations along the taxiway
will have proportional dimensional requirements.
2.2.3 Dual taxiways
or taxiway bypasses can only achieve relative departure priority by separating
the departure stream into two parts. Taxi bypasses can be constructed at a
relatively low cost, but provide only a small amount of flexibility to alter
the departure sequence. A full length dual taxiway is the most expensive
alternative and can only be justified at very high activity aerodromes where
there is a clear need for two-directional movement parallel to the runway. This
need arises when passenger terminal aprons or other facilities are located in
such a manner that they generate aircraft movements opposite to the departure flow.
2.2.4 The dual runway
entrance reduces the take-off run available for aircraft using the entrance not
located at the extremity of the runway. This is not a serious disadvantage if
this entrance can be used by aircraft for which the remaining take-off run is
adequate. A dual runway entrance also makes it possible to bypass an aircraft delayed
on another entrance taxiway or even at the extremity of the runway. The use of
dual entrances in combination with dual taxiways will give a degree of flexibility
comparable to that obtained with a well- designed holding bay. Oblique
entrances permit entry at some speed, but they make it more difficult for the
crew to see aircraft approaching to land and, because of the larger paved area
required, they are more expensive to provide. Though operational and traffic
control groups have advocated designs for runway entry which would permit
acceleration while turning onto the runway, further studies, simulations and
experience will be necessary prior to establishing a recommended design of this
type.
2.2.5 For a given
aerodrome, the best choice between these methods depends upon the geometry of
the existing runway/taxiway system and the volume of aircraft traffic.
Experience shows that local technical and economic considerations will often be
decisive when choosing between the three types (or combinations of types).
These three types can also be used in various combinations to optimize surface
movements of aircraft to the threshold.
2.3 COMMON DESIGN REQUIREMENTS AND CHARACTERISTICS
2.3.1 Regardless of the
type of bypass used, minimum centre line to centre line separations between
taxiways and runways must be maintained as required for the type of runway
served (see Table 1-1).
2.3.2 The cost of
constructing any bypass is directly related to the area of new pavement
required. In addition, indirect costs may result from disruptions to air traffic
during the construction period.
2.3.3 The design
selected should always provide at least one entrance to the beginning of the
runway usable for take-off so that aircraft requiring the entire take-off run
may easily align themselves for take-off without significant loss of runway
length.
2.3.4 Propeller wash
and jet blast from holding aircraft should be directed away from other aircraft
and away from the runway. The preparation and the maintenance of the shoulders
should be as described for taxiway shoulders (see 1.6.6 to 1.6.10).
2.4 SIZE AND LOCATION OF HOLDING BAYS
2.4.1 The space
required for a holding bay depends on the number of aircraft positions to be
provided, the size of the aircraft to be accommodated and the frequency of
their utilization. The dimensions must allow for sufficient space between
aircraft to enable them to manoeuvre independently. In general, the wing tip
clearance (increment) between a parked aircraft and one moving along the
taxiway or apron taxiway should not be less than that given by the following
tabulation:
Code
letter
|
Wing
tip clearance (increment) (m)
|
A
|
6.5
|
B
|
5.75
|
C
|
5
|
D
|
7
|
E
|
7
|
F
|
7
|
2.4.2 When used to allow
flexible departure sequencing, the most advantageous location for a holding bay
is adjacent to the taxiway serving the runway end. Other locations along the
taxiway are satisfactory for aircraft performing pre-flight checks or engine runups
or as a holding point for aircraft awaiting departure clearance. Criteria for
the location of holding bays with respect to the runway are given below.
2.4.3 The distance
between a holding bay and the centre line of a runway should be in accordance
with Table 2-1 and, in the case of a precision approach runway, should be such
that a holding aircraft will not interfere with the operation of radio aids.
Therefore, the aircraft should be clear of the ILS sensitive and critical
areas, and it should not penetrate the obstacle free zone.
2.4.4 At elevations
greater than 700 m, the distance of 90 m specified in Table 2-1 for a precision
approach runway code number 4 should be increased as follows:
a) up to an elevation
of 2 000 m - 1 m for every 100 m in excess of 700 m;
b) elevation in
excess of 2 000 m and up to 4 000 m - 13 m plus 1.5 m for every 100 m in excess
of 2 000 m; and
c) elevation in
excess of 4 000 m and up to 5 000 m - 43 m plus 2 m for every 100 m in excess
of 4 000 m.
2.4.5 If a holding bay
for a precision approach runway code number 4 is at a higher elevation compared
to the threshold, the distance of 90 m specified in Table 2-1 should be further
increased 5 m for every metre the bay is higher than the threshold.
2.4.6 The distance of
107.5 m for code number 4 where the code letter is F is based on an aircraft
with a tail height of 24 m, a distance from the nose to the highest part of the
tail of 62.2 m, a nose height of 10 m, holding at an angle of 45 degrees or
more with respect to the runway centre line and being clear of the obstacle
free zone.
2.4.7 The distance of
90 m for code number 3 or 4 is based on an aircraft with a tail height of 20 m,
a distance from the nose to the highest part of the tail of 52.7 m and a nose
height of 10 m, holding at an angle of 45 degrees or more with respect to the
runway centre line, being clear of the obstacle free zone and not accountable
for the calculation of obstacle clearance altitude/height.
2.4.8 The distance of
60 m for code number 1 or 2 is based on an aircraft with a tail height of 8 m,
a distance from the nose to the highest part of the tail of 24.6 m and a nose
height of 5.2 m, holding at an angle of 45 degrees or more with respect to the
runway centre line, being clear of the obstacle free zone.
2.5 HOLDING BAY MARKING AND LIGHTING
To facilitate
accurate manoeuvring of aircraft on the holding bays, it is desirable to
provide suitable marking and lighting. These will also prevent parked aircraft
from interfering with the passage of other aircraft moving along the adjacent
taxiway. A solid line to be followed by the pilot of the aircraft appears to be
a suitable method. Taxiway edge lighting should be provided on a holding bay
intended for night use. Location and characteristics of the lights should be in
accordance with the specifications for taxiway lighting set out in Annex 14,
Volume I, Chapter 5.
Table
2-1. Minimum distance from the runway centre line to a holding bay
|
Code
number
|
Type of runway
operation
|
1
|
2
|
3
|
4
|
Non-instrument and
take-off
|
30
m
|
40
m
|
75
m
|
75
m
|
Non-precision
approach
|
40
m
|
40
m
|
75
m
|
75
m
|
Precision approach
Category I
|
60
mb
|
60
mb
|
90
ma,b
|
90
ma,b
|
Precision approach
Category II or III
|
-
|
-
|
90
ma,b
|
90
ma,b,c
|
a. If a holding bay
is at a lower elevation compared to the threshold, the distance may be
decreased 5 m for every metre the bay is lower than the threshold, contingent
upon not infringing on the inner transitional surface.
b. This distance
may need to be increased to avoid interference with radio aids; for a
precision approach runway category III the increase may be of the order of 50
m.
c. Where the code
letter is F, this distance should be 107.5 m.
|
CHAPTER 3
APRONS
An apron is a defined
area intended to accommodate aircraft for purposes of loading and unloading passengers,
mail or cargo, fuelling and parking or maintenance. The apron is generally
paved but may occasionally be unpaved; for example, in some instances, a turf
parking apron may be adequate for small aircraft.
3.1 TYPES OF APRONS
Passenger
terminal apron
3.1.1 The passenger terminal
apron is an area designed for aircraft manoeuvring and parking that is adjacent
or readily accessible to passenger terminal facilities. This area is where
passengers board the aircraft from the passenger terminal. In addition to
facilitating passenger movement, the passenger terminal apron is used for
aircraft fuelling and maintenance as well as loading and unloading cargo, mail
and baggage. Individual aircraft parking positions on the passenger terminal
apron are referred to as aircraft stands.
Cargo
terminal apron
3.1.2 Aircraft that
carry only freight and mail may be provided a separate cargo terminal apron
adjacent to a cargo terminal building. The separation of cargo and passenger
aircraft is desirable because of the different types of facilities each
requires both on the apron and at the terminal.
Remote
parking apron
3.1.3 In addition to the
terminal apron, airports may require a separate parking apron where aircraft
can park for extended periods. These aprons can be used during crew layovers or
for light periodic servicing and maintenance of temporarily grounded aircraft. While
parking aprons are removed from the terminal aprons, they should be located as
close to them as is practical to minimize the time for passenger
loading/unloading as well as from a security point of view.
Service
and hangar aprons
3.1.4 A service apron
is an uncovered area adjacent to an aircraft hangar on which aircraft
maintenance can be performed, while a hangar apron is an area on which aircraft
move into and out of a storage hangar.
General
aviation aprons
3.1.5 General aviation
aircraft, used for business or personal flying, require several categories of
aprons to support different general aviation activities.
Itinerant apron
3.1.5.1 Itinerant
(transient) general aviation aircraft use the itinerant apron as temporary
aircraft parking facilities and to access fuelling, servicing and ground transportation.
At aerodromes servicing only general aviation aircraft, the itinerant apron is
usually adjacent to, or an integral part of, a fixed-based operator’s area. The
terminal apron will generally also set aside some area for itinerant general
aviation aircraft.
Base aircraft aprons
or tiedowns
3.1.5.2 General
aviation aircraft based at an aerodrome require either hangar storage or a
tiedown space in the open. Hangared aircraft also need an apron in front of the
building for manoeuvring. Open areas used for base aircraft tiedown may be paved,
unpaved or turf, depending on the size of aircraft and local weather and soil conditions.
It is desirable that they be in a separate location from the itinerant aircraft
aprons.
Other ground
servicing aprons
3.1.5.3 Areas for
servicing, fuelling or loading and unloading should also be provided as needed.
3.2 DESIGN REQUIREMENTS
3.2.1 The design of any
of the various apron types requires the evaluation of many interrelated and often
contradictory characteristics. Despite the distinct purposes of the different apron
types, there are many general design characteristics relating to safety, efficiency,
geometry, flexibility and engineering that are common to all types. The
following paragraphs give a brief description of these general design
requirements.
Safety
3.2.2 Apron design
should take into account safety procedures for aircraft manoeuvring on the
apron. Safety in this context implies that aircraft maintain specified
clearances and follow the established procedures to enter, move within and
depart from apron areas. Services provided to aircraft parked on the apron should
incorporate safety procedures, especially regarding aircraft fuelling.
Pavements should slope away from terminal buildings and other structures to
prevent the spread of fuel fires on the apron. Water outlets should be located
at each stand position for routine hosing of the apron surface. Aircraft
security should also be considered in locating the apron area where the
aircraft can be protected from unauthorized personnel. This is accomplished by
physically separating public access areas from the apron areas.
Efficiency
3.2.3 Apron design should
contribute to a high degree of efficiency for aircraft movements and dispensing
apron services. Freedom of movement, minimum taxi distances and a minimum of
delay for aircraft initiating movements on the apron are all measures of efficiency
for any of the apron types. If the ultimate aircraft stand arrangement can be
determined during the initial planning phase of the aerodrome, utilities and
services should be installed in fixed installations. Fuel lines and hydrants,
compressed air hookups and electrical power systems must be carefully
preplanned because these systems are often placed under the apron pavement. The
high initial cost of these systems will be offset by the increased efficiency
of the stand, which allows greater utilization of the apron. Achieving these
measures of efficiency will ensure the maximum economic value of the apron.
Geometry
3.2.4 The planning and
design of any apron type are dependent upon a number of geometric
considerations. For example, the length and width of a land parcel available
for apron development may preclude the choice of certain apron layout concepts.
For a new aerodrome it may be possible to develop the most efficient
arrangement, based upon the nature of the demand, and then to set aside an area
of land ideally suited to the plan. However, expansion or addition of aprons at
existing aerodromes will usually be less than ideal due to the limitations
imposed by the shape and size of available parcels. The overall area needed per
aircraft stand includes the area required for aircraft stand taxilanes as well
as apron taxiways used in common with other aircraft stands. Therefore, the overall
area needed for apron development is a function not only of aircraft size,
clearances and parking method, but also of the geometric arrangement of
aircraft stand taxilanes, other taxiways, blast fences, areas used for the
stationing of service vehicles and roads for the movement of ground vehicles.
Flexibility
3.2.5 Planning for aprons
should include an evaluation of the following flexibility characteristics.
Range of aircraft
sizes
3.2.5.1 The number
and size of aircraft stands should be matched to the number and size of
aircraft types expected to use the apron. A compromise must be developed between
the extremes of:
a) using one size of
aircraft stand large enough for the largest aircraft type; and b) using as many
different sized stands as there are aircraft types.
The first method is a
highly inefficient use of area, while the second provides a low level of operating
flexibility. For passenger terminal aprons, a compromise solution that achieves
adequate flexibility is to group the aircraft into two to four size classes and
provide stands for a mix of these general sizes in proportion to the demand
forecast. A greater number of general aviation parking space sizes can be used
because the space may be leased and occupied by a single aircraft of known
dimensions.
Expansion capability
3.2.5.2 Another key
element of a flexible apron system is allowance for expansion to meet future
needs. To avoid undue restriction of the growth potential of a particular apron
area, the apron should be designed in modular stages so that successive stages become
integral additions to the existing apron with a minimum of disruption to ongoing
activities.
Common
design characteristics
3.2.6 Many technical design
requirements for the construction of apron surfaces are common to all apron
types. Several of these factors are described in the following paragraphs.
Pavement
3.2.6.1 The choice of
pavement surface is determined by evaluating aircraft mass, load distribution,
soil conditions and the relative cost of alternative materials. Reinforced
concrete is routinely used at aerodromes serving the largest commercial
aircraft where greater strength and durability are needed. As a minimum, most
aerodromes require an asphalt (tarmac) surface to satisfy strength, drainage
and stabilization criteria, though turf and cement-stabilized sand aprons have
been satisfactorily used in some locations. Reinforced concrete is usually more
expensive to install than asphalt but is less expensive to maintain and usually
lasts longer. In addition, concrete is relatively unaffected by spilled jet fuel,
whereas asphalt surfaces are damaged if fuel remains on the surface for even
short periods of time. This problem can be partially overcome by coating the
asphalt with special sealants and by frequently washing off the pavement.
Pavement slope
3.2.6.2 Slopes on an
apron should be sufficient to prevent accumulation of water on the surface of
the apron but should be kept as level as drainage requirements permit.
Efficient storm drainage of large, paved apron areas is normally achieved by
providing a steep pavement slope and numerous area drains. On aprons, however, too
great a slope will create manoeuvrability problems for aircraft and service vehicles
operating on the apron. Additionally, fuelling of aircraft requires nearly a
level surface to achieve the proper fuel mass balance in the assorted aircraft
storage tanks. The design of slopes and drains should direct spilled fuel away
from building and apron service areas. In order to accommodate the needs for
drainage, manoeuvrability and fuelling, apron slopes should be 0.5 to 1.0 per
cent in the aircraft stand areas and no more than 1.5 per cent in the other
apron areas.
Jet blast and
propeller wash
3.2.6.3 The effects
of extreme heat and air velocities from jet and propeller engines must be
considered when planning apron areas and adjacent service roads and buildings.
For some aerodromes, it may be necessary to provide greater
aircraft-to-aircraft separations or erect blast fences between parking spaces
to counteract these effects. Appendix 2 gives greater detail on this design
consideration.
3.3 BASIC TERMINAL APRON LAYOUTS
General
considerations
3.3.1 The type of
terminal apron parking layout best suited to a particular aerodrome is a
function of many interrelated criteria. Design of the terminal apron must, of course,
be completely consistent with the choice of terminal design and vice versa. An
iterative procedure for selecting the best combination of apron and terminal
design should be used to compare the advantages and disadvantages of each system
analysed separately. The volume of aircraft traffic using the terminal is an
important factor in determining the apron layout that is most efficient in serving
a particular terminal design. In addition, an aerodrome with a disproportionate
percentage of international transfer (direct connection with another flight) or
locally originating passengers may need a specialized terminal and apron system
design to accommodate the skewed characteristic of the passenger traffic.
Passenger
loading
3.3.2 The passenger
loading method to be used must be taken into account when planning the apron
layout. Some methods can be used with only one or two of the basic parking
layouts.
3.3.2.1 Direct upper level
loading is made possible by the development of the loading bridge, permitting
the passenger to board the aircraft from the upper level of the terminal
building. Two types of aircraft loading bridges are illustrated in Figure 3-1:
a) The stationary
loading bridge. A short loading bridge which extends from a projection in
the building. The aircraft parks nose-in alongside the projection and stops
with the aircraft front door opposite the bridge. The bridge extends a very
short distance to the aircraft, allowing very little variation between the
height of the aircraft main deck and the terminal floor.
b) The apron drive
loading bridge. A bridge which has one end of a telescoping gangway hinged to
the terminal building and the other end supported by a steerable, powered dual-wheel.
The bridge pivots towards the aircraft and lengthens until it reaches the
aircraft door. The end mating with the aircraft can be raised or lowered
significantly, permitting aircraft of varying deck heights to be served from
the loading bridge.
3.3.2.2 There are
other basic passenger loading methods used in addition to aircraft loading
bridges:
a) Movable steps. Movable
steps are pushed or driven to the aircraft and set at door level. Passengers
walk in the open on the apron or are driven by bus between the terminal and the
aircraft and use the steps to board the aircraft.
b) Passenger
transporters. Passengers board a bus or specially designed passenger
transporter at the terminal building and are driven to a remote aircraft stand.
Passengers then may use steps to board the aircraft or board the aircraft from
the same level as the aircraft floor, i.e. by elevation of the vehicle.
c) Aircraft-contained
steps. This procedure is similar to the movable steps and can be used with
any aircraft equipped with self-contained steps. After stopping, the crew
releases the self-contained steps and passengers walk on the apron or are
driven by bus between the aircraft and the terminal building.
Passenger
terminal apron concepts
3.3.3 The design of
passenger terminal aprons is directly interrelated with the passenger terminal
concept. Determination of passenger terminal concepts is described in the Airport
Planning Manual (Doc 9184), Part 1 - Master Planning. Various
apron/terminal concepts are illustrated in Figure 3-2, and the characteristics
of each concept from the viewpoint of the apron are briefly described below.
Simple concept
3.3.4 This concept is
to be applied at low-traffic-volume airports. Aircraft are normally parked
angled either nose in or nose-out for self-taxi in and taxi out. Consideration
should be given to providing adequate clearance between apron edge and airside
terminal frontage to reduce the adverse effects of jet engine blast. Where this
is not done, jet engine blast fences should be provided. Apron expansion can be
done incrementally in accordance with demands, causing little disruption to
airport operation.
Figure
3-1. Passenger loading bridges
Figure
3-2. Passenger terminal apron concepts
Linear concept
3.3.5 The linear
concept may be regarded as an advanced stage of the simple concept. Aircraft
can be parked in an angled or parallel parking configuration. However, the nose-
in/push-out parking configuration with minimum clearance between apron edge and
terminal is more common in this concept because of more efficient utilization of
apron space and handling of aircraft and passengers. Nose-in parking affords relatively
easy and simple manoeuvring for aircraft taxiing into gate position. Push-out
operations cause little disruption of apron activities in neighbouring gate positions.
However, towing tractors and skilled operators are required. At busy traffic
airports, it may become necessary to provide double apron taxiways to lessen
the blocking of the taxiway by push-out operations. The corridor between the
apron edge and terminal frontage can be used for circulation of apron traffic,
and the area around the nose of the parked aircraft can be used for ground service
equipment parking slots. When apron depth is planned from the outset to cater
to the longest fuselage length, the linear concept has as much flexibility and
expansibility as the simple concept and almost as much as the open apron
concept.
Pier (finger) concept
3.3.6 As seen in
Figure 3-2, there are several variations on this concept, according to the
shape of the pier. Aircraft can be parked at gate positions on both sides of
the piers, either angled, parallel or perpendicular (nose-in). Where there is
only a single pier, most advantages of the linear concept would apply for
airside activities with the exception that the pier concept has a limited
incremental expansion capability. When there are two or more piers, care must
be taken to provide proper space between them. If each pier serves a large
number of gates, it may be necessary to provide double taxiways between piers
to avoid conflicts between aircraft entering and leaving the gate positions. It
is important to provide sufficient space between two or more piers to cater to
future larger aircraft.
Satellite concept
3.3.7 The satellite concept
consists of a satellite unit, surrounded by aircraft gate positions, separated
from the terminal. The passenger access to a satellite from the terminal is
normally via an underground or elevated corridor to best utilize the apron
space, but it could also be on the surface. Depending on the shape of the
satellite, the aircraft are parked in radial, parallel or some other
configuration around the satellite. When aircraft are parked radially,
push-back operation is easy but requires larger apron space. If a wedge-shaped
aircraft parking configuration is adopted, it not only requires unfavourable
sharp turns taxiing to some of the gate positions but also creates traffic congestion
of ground service equipment around the satellite. A disadvantage of this concept
is the difficulty of incremental expansion which means that an entire new unit
would need to be constructed when additional gate positions are required.
Transporter (open)
apron concept
3.3.8 This concept
may be referred to as an open or remote apron or transporter concept. As aprons
may be ideally located for aircraft, i.e. close to the runway and remote from
other structures, this concept would provide advantages for aircraft handling,
such as shorter overall taxiing distance, simple self-manoeuvring, ample flexibility
and expansibility of aprons. However, as it requires transporting passengers, baggage
and cargo for relatively longer distances by transporters (mobile
lounges/buses) and carts to and from the terminal, it can create traffic
congestion problems on the airside.
Hybrid concept
3.3.9 The hybrid
concept means the combining of more than one of the above-mentioned concepts.
It is fairly common to combine the transporter concept with one of the other
concepts to cater to peak traffic. Aircraft stands located at remote areas from
the terminal are often referred to as remote aprons or remote stands.
3.4 SIZE OF APRONS
General
3.4.1 The amount of area
required for a particular apron layout depends upon the following factors:
a) the size and
manoeuvrability characteristics of the aircraft using the apron;
b) the volume of
traffic using the apron;
c) clearance requirements;
d) type of ingress
and egress to the aircraft stand;
e) basic terminal
layout or other airport use (see 3.3);
f) aircraft ground
activity requirements; and
g) taxiways and
service roads.
Aircraft
size
3.4.2 The size and
manoeuvrability of the mix of aircraft expected to use a given apron must be known
before a detailed apron design can be undertaken. Figure 3-3 shows the
dimensions needed for sizing an aircraft stand space, and Table 3-1 lists
dimensions for some typical aircraft. The overall aircraft size dimensions -
total length (L) and wing span (S) - can be used as the starting point
in establishing the overall apron area requirement for an aerodrome. All other
areas needed for clearances, taxiing, servicing, etc., must be determined with
regard to this basic aircraft “footprint”. The manoeuvrability characteristics
of an aircraft are a function of the turning radius (R) which is in turn
related to the location of the aircraft turning centre. The turning centre is
the point about which the aircraft pivots when turning. This point is located
along the centre line of the main undercarriage at a variable distance from the
fuselage centre line depending upon the amount of nosewheel angle used in the
turning manoeuvre. The values listed in Table 3-1 for the turning radii are
derived from the nosewheel angles as listed. In most cases, these radii values
are measured from the turning centre to the wing tip; however, on some
aircraft, the turning radii are measured from the turning centre to the
aircraft nose or to the horizontal stabilizers.
Traffic volumes
3.4.3 The number and
size of aircraft stand positions needed for any type of apron can be determined
from forecasts of aircraft movements at a given aerodrome. The forecast of
apron activity must be broken down into an appropriate demand planning period
for the type of apron involved. The apron need not be designed for extraordinary
peak periods of activity, but should be able to accommodate a reasonable peak
activity period with a minimum amount of delay. For example, the number of
passenger terminal aircraft stands should be adequate to handle the peak hour traffic
of the average day of the peak month. The peak period for accumulation of cargo
aircraft is longer than an hour and less than a day; therefore, the cargo apron
should handle the average day’s activity of the peak month. Other apron types
should have enough parking spaces to handle their appropriate peak period of
activity. In addition, planning for aprons should be broken into several phases
to minimize the capital cost outlays needed. Apron areas should then be added
as needed to accommodate the growth in demand.
* Determined by nose
tip or tail tip on some aircraft
Figure
3-3. Dimensions for sizing aircraft stand spacing
Table
3-1. Selected aircraft dimensions
Aircraft type
|
Length
(m)
|
Wing
span (m)
|
Nose
wheel angle
|
Turning
radius (m)
|
A300BB2
|
46.70
|
44.80
|
50°
|
38.80a
|
A320-200
|
37.57
|
33.91
|
70°
|
21.91c
|
A330/A340-200
|
59.42
|
60.30
|
65°
|
45.00a
|
A330/A340-300
|
63.69
|
60.30
|
65°
|
45.60a
|
B727200
|
46.68
|
32.92
|
75°
|
25.00c
|
|
|
|
|
|
B737200
|
30.58
|
28.35
|
70°
|
18.70a
|
B737-400
|
36.40
|
28.89
|
70°
|
21.50c
|
B737-900
|
41.91
|
34.32
|
70°
|
24.70c
|
B747
|
70.40
|
59.64
|
60°
|
50.90a
|
B747400
|
70.67
|
64.90
|
60°
|
53.10a
|
|
|
|
|
|
B757-200
|
47.32
|
37.95
|
60°
|
30.00a
|
B767-200
|
48.51
|
47.63
|
60°
|
36.00a
|
B767-400 ER
|
51.92
|
61.37
|
60°
|
42.06a
|
B777-200
|
63.73
|
60.93
|
64°
|
44.20a
|
B777-300
|
73.86
|
73.08
|
64°
|
46.80a
|
|
|
|
|
|
BAC 111400
|
28.50
|
27.00
|
65°
|
21.30a
|
DC861/63
|
57.12
|
43.41/45.2
|
70°
|
32.70c
|
DC930
|
36.36
|
28.44
|
75°
|
20.40c
|
DC940
|
38.28
|
28.44
|
75°
|
21.40c
|
DC950
|
40.72
|
28.45
|
75°
|
22.50c
|
|
|
|
|
|
MD82
|
45.02
|
32.85
|
75°
|
25.10b
|
MD90-30
|
46.50
|
32.87
|
75°
|
26.60b
|
DC1010
|
55.55
|
47.35
|
65°
|
35.60a
|
DC1030
|
55.35
|
50.39
|
65°
|
37.30a
|
DC1040
|
55.54
|
50.39
|
65°
|
36.00a
|
|
|
|
|
|
MD11
|
61.60
|
52.50
|
65°
|
39.40a
|
L1011
|
54.15
|
47.34
|
60°
|
35.59a
|
a. Towing tip
b. Tonose
c. Totail
|
Clearance
requirements
3.4.4 An aircraft stand
should provide the following minimum clearances between aircraft using the
stand as well as between aircraft and adjacent buildings or other fixed
objects.
Code
letter
|
Clearance
(m)
|
A
|
3.0
|
B
|
3.0
|
C
|
4.5
|
D
|
7.5
|
E
|
7.5
|
F
|
7.5
|
The clearances for
code letters D, E and F can be reduced in the following locations (for aircraft
using a taxi-in, push-out procedure only):
a) between the
terminal (including passenger loading bridges) and the nose of an aircraft; and
b) over a portion of
the stand provided with azimuth guidance by a visual docking guidance system.
These clearances may,
at the discretion of the airport planners, be increased as needed to ensure
safe operation on the apron. Location of aircraft stand taxilanes and apron
taxiways should provide the following minimum separation distance between the
centre line of these
taxiways and an
aircraft at the stand:
Minimum
separation distances
Code
letter
|
Aircraft
stand taxilane centre line to object
(m)
|
Apron
taxiway centre line to object
(m)
|
A
|
12.0
|
15.5
|
B
|
16.5
|
20.0
|
C
|
22.5
|
26.0
|
D
|
33.5
|
37.0
|
E
|
40.0
|
43.5
|
F
|
47.5
|
51.0
|
Types
of aircraft stand ingress and egress
1.1.5 There are
several methods used by an aircraft to enter and leave an aircraft stand: it may
enter and leave under its own power; it may be towed in and towed out; it may
enter a position under its own power and be towed or pushed out. However, in
considering apron size requirements, the various methods can be categorized as
either selfmanoeuvring or tractor- assisted.
1.1.5.1 Self-manoeuvring.
This term denotes the procedure whereby an aircraft enters and leaves the
aircraft stand under its own power, that is, without recourse to a tractor for
any part of the manoeuvre. Figure 3-4 a), b) and c) shows the area required for
aircraft manoeuvring into and out of an aircraft stand position for angled nose-in,
angled nose-out and parallel parking configuration, respectively. The normal manoeuvre
of taxiing into and out of an aircraft stand adjoining the terminal building or
pier by nose-in or nose-out parking configuration involves a 180 degree turn as
shown in Figure 3-4 a) and b). The radius of this turn and the geometry of the
aircraft are among the factors which determine the aircraft stand spacing.
Although this method of parking requires more pavement area than
tractor-assisted methods, this is offset by a saving of the equipment and
personnel required for the tractor operation. Thus these methods are common at airports
with a relatively small volume of traffic. Figure 3-4 c) illustrates the stand spacing
for self-manoeuvring aircraft, which is contingent upon the angle at which the aircraft
can comfortably manoeuvre into a stand position with other aircraft parked in
the adjacent positions. While this parking configuration affords easiest
manoeuvring for aircraft to taxi-in/out, it requires the largest apron area. In
addition, due consideration should be given to the adverse effect of jet blast
on servicing crew and equipment in neighbouring aircraft stands.
1.1.5.2 Tractor-assisted.
This term applies to any method of ingress and egress that requires the use
of a tractor and tow bar. Most of the world’s busiest aerodromes use some
variation of tractor-assisted methods. The most common procedure is the
taxi-in, push-out method, but aircraft can also be towed in and out in other
combinations. Use of tractors allows a much closer spacing of aircraft stands, reducing
both the apron and terminal space required to accommodate a high volume of
terminal aircraft parking. Figure 3-4 d) shows the area required for aircraft that
taxi in and push out perpendicular to the terminal building. Clearly this
procedure results in a more efficient use of apron space than the
selfmanoeuvring procedure. This is a simple manoeuvre which can be done without
creating excessive engine blast problems for apron personnel and equipment or
the terminal building. The requirement for jet blast fences is also reduced or
eliminated by adopting this procedure. Generally, some type of guidance system
is provided for pilots to position aircraft accurately in the gate position.
The departure manoeuvre is more complicated and usually involves the aircraft being
pushed backward by a tractor onto the taxiway while at the same time being
turned up to 90 degrees. Normally the push-back operation is carried out
without the engines started. It takes an average of 3 to 4 minutes from the
beginning of the push-back until the tractor is disconnected and the aircraft
is moving under its own power. The push-out operation requires skill and
practice on the part of the driver to avoid over-castoring the nose wheel and,
on slippery pavement, to keep the aircraft moving while simultaneously
maintaining directional control because of the reduced traction.
1.1.5.3 Stand spacing.
General formulas have been developed in a number of cases to calculate the
required distance between aircraft stands. The simplest case is for aircraft
that taxi in perpendicular to the terminal building and push out straight back.
As shown in Figure 3-4 d), the minimum stand spacing (D) equals the wing
span (S) plus the required clearance (C).
1.1.5.4 For other
ingress and egress procedures, or for other parking angles, the geometry is
more complex and a detailed analysis needs to be undertaken to determine stand
spacings. Manufacturers’ technical data should be consulted to determine the wing
tip radii and operating characteristics for those aircraft likely to use these more
complex manoeuvring techniques.
Aircraft
ground servicing
1.1.6 Passenger
aircraft services that are carried out during the time an aircraft is parked in
a stand position include: galley, toilet and potable water service; baggage
handling; fuelling; provision of air conditioning, oxygen, electrical power
supply and starting air; and aircraft towing. Most of these functions have a
vehicle and/or equipment associated with them or have some type of fixed
installation established to conduct these services. Figures 3-5 and 3-6 show a
typical ground equipment service layout for a medium-sized aircraft. The area
to the right of the aircraft nose forward of the wing is often used as a
pre-positioned service area to store vehicles and equipment when the nose-
in/push-out parking configuration is adopted.
Figure
3-4. Clearance area required for terminal stand ingress and egress
Figure
3-5. Typical ground equipment service layout (Boeing 737 - MAX)
Figure
3-6. Typical ground equipment service layout (Airbus A350-900)
Taxiways
and service roads
General
1.1.7 The total area
needed for an apron includes not only the individual aircraft stands, but also
the area required for apron taxiways, aircraft stand taxilanes and service
roads needed to access the aircraft stands and provide necessary support services.
Locations for these facilities will depend upon the terminal arrangement,
runway locations and locations of off- apron services such as flight kitchens,
fuel farms, etc.
Apron taxiways
1.1.8 Chapter 1 of
this manual defines apron taxiways and aircraft stand taxilanes and their
interaction with the aircraft stands. Aircraft stand taxilanes branch off of
apron taxiways, which in turn are generally located on the edge of the apron
pavement.
Service roads
1.1.9 Chapter 4 of
this manual discusses the need for and location of service roads. The space
needed for service roads must be considered during the overall apron planning.
They are usually located either adjacent and parallel to the terminal building
or on the airside of the aircraft stand parallel to the aircraft stand taxilane.
The width required will depend upon the anticipated level of traffic and
whether a one-way road system can be developed. If the service road is located
adjacent to the terminal building, adequate clearance must be available under
the loading bridges for the largest vehicles expected to use the road. If the
service road is not adjacent to the terminal building, the difficulty of
providing the necessary headroom under bridges is eliminated, but it introduces
the problem of vehicle/aircraft conflict. Overall apron planning should also
take into account manoeuvring and storage areas for ground equipment.
3.5 APRON GUIDANCE
In the Aerodrome Design
Manual (Doc 9157), Part 4 - Visual Aids, the benefits of apron
marking and lighting, as well as guidance on aircraft stands, are discussed.
The objective of guidance on aircraft stands is to provide safe manoeuvring of
aircraft on the aircraft stand and precise positioning of aircraft. Generally,
during good visibility periods, the use of painted lines and, if necessary,
marshallers will ensure safe, accurate movements. Floodlighting on the apron
area should be added for night operations and when visibility is poor, pavement
centre line lighting should be provided. Visual docking guidance systems provide
accurate guidance for an aircraft parking under its own power.
3.6 DE-ICING/ANTI-ICING FACILITIES
Location
3.6.1 Centralized
de-icing/anti-icing facilities at or adjacent to terminals can be used if the
demand for gate positions would not cause excessive delays, congestion and long
waiting periods, and if the taxiing time from the terminal to the take-off
runway would be less than the hold-over time of the fluid being used. An
off-gate facility or a remote facility would permit better utilization of
aircraft stands, compensate for changing weather conditions due to a shorter
taxiing time and, consequently, ensure availability of a greater portion of the
hold- over time.
3.6.2 An off-gate
facility along a taxiway may lead to queuing of aeroplanes and thus should have
bypass taxiing capability as shown in Figure 3-7. An off-gate facility better
permits collection of de-icing/anti-icing fluid run-off for its safe disposal than
do aircraft stands. Where holding bays of adequate size and capacity are
provided, these could be used for de-icing/anti-icing of aeroplanes provided
all the above requirements are fulfilled. The taxiing routes for access to the de-icing/anti-icing
pads should have minimum turns and intersections for expediting the movement of
aeroplanes, while not affecting operational safety.
3.6.3 In order that
de-icing/anti-icing facilities may operate efficiently, and to prevent the
likelihood of runway incursions by service vehicles, vehicle service roads or
staging areas may be required. Consideration should be given to ensure that the
emergency response times of aerodrome rescue and fire fighting vehicles are not
compromised. These service roads should take into account operational and safety
factors (prevention of runway/taxiway incursions) as well as environmental
factors (management of de-icing/anti-icing fluid run-off, etc.). Appropriate
surface movement guidance and control (SMGC) signs, such as vehicle stop signs
or road-holding position signs, may need to be installed.
Figure
3-7. Minimum separation distance on a de-icing/anti-icing facility
Factors
affecting the size of the de-icing/anti-icing facility
3.6.4 The size of a
de-icing/anti-icing facility is dependent on the size of the aircraft, the
number of aircraft requiring the treatment, the meteorological conditions, the type
and capacity of the dispensing equipment used and the method of treatment. An
indication of the total size of the facility could be estimated from the number
of aircraft requiring treatment at a given time. The transit time of de-icing/anti-icing
vehicles between the refilling/storage area and the de-icing/anti-icing
facilities should also be taken into account.
Factors
affecting the number of de-icing/anti-icing pads
3.6.5 The number of
pads required is dependent on:
a) the meteorological
conditions - at airports where wet snow or freezing rain conditions are more
prevalent, a greater number of de-icing/anti-icing pads are recommended to be
provided to prevent unacceptable delays;
b) the type of aeroplanes
to be treated - narrow-body aeroplanes require less processing time than do wide-body
aeroplanes. Aeroplanes with fuselage- mounted engines require more processing
time than those with wing-mounted engines;
c) the method of
application of de-icing/anti-icing fluid - the method may be either the
one-step or two- step de-icing/anti-icing procedure. As the latter procedure
results in longer occupancy times, the number of de-icing/anti-icing pads
required should be based on the two-step procedure for flexibility and also to
ensure that the maximum aeroplane departure flow rates are not adversely
affected;
d) the type and
capacity of the dispensing equipment used - mobile de-icing/anti- icing
equipment with small tank capacities and requiring extended fluid heating times
can increase application times and adversely affect the aeroplane departure
flow rates; and
e) the departure flow
rates - the number of aeroplanes to be treated should match the number of
takeoff operations that can be cleared to minimize possible delays and airport
congestion.
Environmental
considerations
3.6.6 The size of a
de-icing/anti-icing pad should be equal to the parking area required for the
most demanding aeroplane and should also provide a 3.8 m vehicle movement area
all round. Where more than one de-icing/anti-icing pad is provided, there
should be no overlap of the vehicle movement area required exclusively for each
pad. Furthermore, while planning the total size of a de-icing/anti-icing
facility, the minimum clearances specified in Chapter 3 of Annex 14, Volume I
should be taken into account.
3.6.7 Excess de-icing/anti-icing
fluid running off an aeroplane poses the risk of contamination of ground water
if allowed to mix with other surface run-off. Furthermore, the fluids also have
an adverse effect on the pavement surface friction characteristics. Therefore,
it is imperative that an optimum quantity be used. Nevertheless, all excess
fluids must be properly collected to prevent ground water contamination. All
surface run-off from such areas must be adequately treated before discharging
into storm water drains.
3.6.8 One approach
would be to collect all apron surface run-off at a collection point where the
contaminated run-off could be suitably treated before discharging it to the
storm water drains. Grooving of the pavement would facilitate in the collection
of all excess de- icing/anti-icing fluids. In case of remote
de-icing/anti-icing pads, the collection and handling of the excess fluid is
relatively easier than at aircraft stands.
CHAPTER 4
SEGREGATION OF TRAFFIC ON THE MOVEMENT AREA
4.1 NEED FOR TRAFFIC
SEGREGATION
4.1.1 The potential
for aircraft and ground vehicle interactions exists on the runways, taxiways
and aprons that make up the aircraft movement area. The number of interactions
can be minimized, however, in the planning phase of the aerodrome facility by
segregating the air and ground traffic. Properly segregated traffic will
minimize the possibility of aircraft and ground vehicle collisions and maximize
the efficiency of aircraft movements. Those interactions that are necessary
should be planned for predesignated areas using established procedures.
4.1.2 There is a need
for some ground vehicles to operate on the movement area for the purposes of
aircraft servicing, aerodrome maintenance and construction work, and emergency
operations. However, because of the different physical characteristics of aerodromes,
no specific design criteria can be established to promote segregation of traffic.
There are, however, a number of measures that may be taken to lessen the amount
of mixing of aircraft and ground vehicles.
4.2 ACTIVITIES CAUSING A MIX OF AIRCRAFT AND
GROUND VEHICLES
4.2.1 The majority of
interactions that can occur between aircraft and ground vehicles take place on
apron areas. The following are some aircraft servicing operations performed on
aprons that may involve attendance of ground vehicles and that should be taken
into account when planning segregation of traffic on aprons:
a) passenger
unloading/loading;
b) baggage
unloading/loading;
c) cargo and/or mail
unloading/loading;
d) galley service;
e) sanitation
service;
f) fuelling service;
g) provision of
compressed air forengine starting;
h) aircraft
maintenance; and
i) electric power and
air conditioning (if not provided by aircraft auxiliary power units).
In addition,
provision should be made for emergency and security vehicles on the apron
areas.
4.2.2 Ground vehicle activities
that occur on movement areas outside of the aprons include the following:
a) Emergency operations.
Rescue and firefighting equipment, which may be required at any point on the
aerodrome or runway approach areas;
b) Security operations.
Small vehicles used for the patrol of fence lines and restricted areas;
c) Aerodrome maintenance
and construction. Repair of pavements, navigation aids and lighting, grass mowing,
snow/ice removal operations, etc.
4.3 METHODS TO ACHIEVE SEGREGATION
4.3.1 Several general
concepts for achieving segregation of traffic are presented in the following
paragraphs. For apron areas in particular, the degree of segregation which can
be achieved depends largely on the available space. The greater the amount of
space available for a given number of aircraft stands, the easier it is to
segregate types of traffic. Normally, the need for economy is such that aprons
are rarely designed with excess area and, in any case, air traffic growth
generally absorbs any designed spare apron area. The degree of segregation
necessary is dependent on the dimensions and other characteristics of aircraft
(e.g. wing span, manoeuvrability and jet blast) and the nature of the ground vehicles.
In addition, when planning an aerodrome, aircraft operators should be consulted
to determine their anticipated ground vehicle movement requirements.
Exclusion
4.3.2 Although the
design of aerodrome facilities can ease considerably the problem of mixing of
aircraft with ground vehicles, it is nevertheless most important that aircraft
operators be conscious of the need to keep the volume of their ground traffic
to a minimum. All ground vehicles whose function does not require them to be on
the movement area should be excluded. This practice is also in accord with
basic aerodrome security measures. Landside road systems should be designed so
that public vehicles have access to all public areas of an aerodrome without travelling
on the movement area. Measures should also be taken to prevent unauthorized
access of public vehicles to the movement area. This requires the provision of
fences, gates and other security systems needed to strictly control access.
Service
roads for ground vehicles
4.3.3 Airside service
roads for ground vehicles can eliminate or lessen to a great extent the
necessity for the use of runways and taxiways by ground vehicles. Such roads
should be planned so that at least the critical sections of the movement area
for traffic congestion can be bypassed by ground vehicular traffic. For
example, these roads may be used as aerodrome perimeter service roads providing
access to navigation aids, as temporary roads for construction vehicles or as
airside roads between terminal buildings and aprons for the passage of airline
vehicles, baggage trains, etc. For terminals with passenger loading bridges,
airside roads may (for some designs) pass beneath the immovable part of the
loading bridge. Figure 4-1 shows examples of airside service roads used on
aprons.
4.3.4 Some general
considerations in the planning of roads are described as follows:
a) Every effort
should be made to plan airside service roads so that they do not cross runways
and taxiways. At high-traffic aerodromes, road tunnels beneath runways and
taxiways should be considered at major intersections in order to avoid such
crossings;
Figure
4-1. Examples of airside service roads
b) The planning of
the aerodrome road layout should take into account the need to provide
emergency access roads for use by rescue and fire fighting vehicles to various
areas on the aerodrome and in particular to the approach areas up to 1 000 m
from the threshold, or at least within the aerodrome boundary;
c) Service roads to navigation
aids should be planned in such a manner as to present minimal interference to
the function of the aids. If it is necessary for an access road to cross an
approach area, the road should be located so that vehicles travelling on it are
not obstacles to aircraft operations; and
d) The airside
service road system must be designed to account for local security measures.
Access points to the system will thus need to be restricted. Should ground
vehicle movements affect surface movement of aircraft on runways and taxiways,
it will be required that the ground vehicle movements be coordinated by the
appropriate aerodrome control. Control is normally exercised by means of twoway
radio communication, although visual signals, such as signal lamps, are
adequate when traffic at the aerodrome is light. Signs or signals may also be
employed to aid control at intersections.
Fixed
servicing installations
4.3.5 Many apron
service vehicles can be eliminated with the provision of fixed servicing installations
set either within the apron or within the terminal buildings adjacent to the
aircraft stands. For example, the provision of hydrant fuelling systems,
compressed air outlets, static power supplies, drainage outlets, drinking water
hydrants, air conditioning outlets and telephone outlets close to aircraft stands
would considerably reduce the equipment and vehicles required for aircraft
servicing. Loading bridges for passenger loading and unloading can also be
thought of as a form of fixed servicing installation as they eliminate the need
for passenger loading equipment and the need for passengers to travel over the
apron (either by walking or in a passenger transport vehicle). Furthermore, loading
bridges generally lend themselves to the provision of fixtures for aircraft servicing
operations. Some of the disadvantages of fixed servicing installations are high
initial costs and limited flexibility for different aircraft types. However, if
in the planning stage careful consideration is given to the location and number
of these facilities, the required flexibility can be achieved. In addition, the
different power supply requirements of present-day aircraft complicate the
provision of static power supplies; however, the trend in aircraft design is
towards greater standardization of electrical requirements. See the Airport Planning
Manual (Doc 9184), Part 1 - Master Planning, for planning
considerations regarding fixed servicing installations.
Markings
4.3.6 Paint markings should
be used to facilitate the segregation of traffic on aprons.
Markings can be used
to provide guidance to pilots in manoeuvring their aircraft safely and
expeditiously on aprons. Other markings are used to designate safety limits for
placement of equipment on aprons, e.g. wing tip clearance lines and other
markings used to delineate access routes for ground vehicles, passengers or
personnel across the apron. There should be a colour change between lines to
distinguish one from another.
APPENDIX 1
FILLET DESIGN
1. TERMINOLOGY AND SYMBOLS
1.1
General
A description of the
terms and symbols used in this appendix is given below. Throughout this
appendix it is assumed that the aircraft is taxiing on a horizontal pavement.
1.2
Terms related to the aircraft
(see
Figure A1-1)
Centre line through
main undercarriage. Line
from the turning centre perpendicular to the aircraft longitudinal axis.
Datum length (d). Distance between aircraft
datum point and centre line through undercarriage.
Datum point of
aircraft (S). Point
on longitudinal axis of aircraft which follows the guideline on the ground. The
datum point is located vertically beneath the cockpit of the aircraft.
Main undercarriage
centre (U). Point
of intersection of longitudinal aircraft axis and centre line through main
undercarriage.
Nose wheel steering
angle. Angle
formed by the longitudinal axis of aircraft and the direction of the nose
wheel.
Steering angle (fi). Angle formed by the
tangent to the guideline and the longitudinal axis of aircraft.
Track of the main undercarriage
(T). Distance
between the outer main wheels of aircraft including the width of the wheels.
Turning centre (P). Centre of turn of
aircraft at any time.
1.3
Terms related to taxiway and fillet design
(see Figure A1-2)
Deviation of main
undercarriage (Ả). Distance
between main undercarriage centre (U) and the guideline measured at
right angles to the latter.
Guideline. Line applied to the
pavement by means of markings and/or lights which the aircraft datum point must
follow while taxiing.
Guideline centre (O).
Centre
of curvature of guideline at point S.
1.4
Glossary of symbols
The following symbols
are used when describing the path of the main undercarriage centre and the
design of the fillets (see Figures A1-1 and A1-2).
d = aircraft datum
length
M = minimum clearance
distance between outer wheels of main undercarriage leg and edge of pavement
O = centre of curvature
of guideline at point S
P = turning centre
r = radius of fillet
arc
R = radius of curvature
of guidelineat point S S = datum point of aircraft
T = track of the main
undercarriage
U = main undercarriage
centre
α = angle between the
radial line OU and the tangent to the path of the main undercarriage
centre at U
β = steering angle
ƛ = main
undercarriage deviation
p and 3 =
polar coordinates of a point [(s) or (U), as applicable]
2. DETERMINATION OF THE PATH FOLLOWED BY THE
MAIN UNDERCARRIAGE OF A TAXIING AIRCRAFT
2.1 Determination of the path by calculation
General
2.1.1 In general, the
junction or intersection of taxiways with runways, aprons and other taxiways is
achieved by means of an arc of a circle (Figure A1-2B). The calculations below
are therefore restricted to the solutions based on this assumption.
Nevertheless, the following calculation is more general than the one strictly
necessary for the study of fillets. It also applies to movement of an aircraft leaving
its parking position on an apron or manoeuvring on a holding bay.
Figure
A1-1.Terms and symbols related to aircraft
Note: Figure shows:
a) the location of
the taxiway centre line;
b) two fillets, each
comprising an arc of a circle and two tangents;
c) the aeroplane
cockpit follows the taxiway centre line.
B.
Terms
Figure
A1-2. Terms and symbols related to taxiway and fillet design
Datum point (S)
follows an arc of a circle
Locus of main
undercarriage centre (U)
2.1.2 Because of the
simplifying assumption above, the datum point of the aircraft (S) follows
an arc of a circle with centre O and radius R during the turn. In
order to describe the movement of a taxiing aircraft, it is necessary to have a
reference coordinate system. Let OX be the datum line, ρ and θu
be the polar coordinates of U (see Figure A1-3). During movement, the
straight line US remains a tangent to the path of the point U at U.
This condition produces the differential equation for the locus of U:
Figure
A1-3. Study of the path of the main under carriage
2.1.3 Special
case: R = d. Integration is only easy in the particular case when R = d (see
Figure A1-3B). Indeed, if R, the radius of curvature of the guideline,
is equal to d, then the datum length of the aircraft would be:
2.1.4 General
case: R ≠ d. If R is not equal to d, equation (4) can only be
evaluated by solving an elliptical integral. Such an evaluation requires appreciable
calculations which cannot be justified for the purpose of fillet design. The alternative
method using an approximation described in 2.1.2 equation (4) avoids
excessively laborious calculation and still provides a fillet design of
adequate accuracy.
2.1.5 Knowledge of
the steering angle (β) at any point of the path of the aircraft datum point (s)
easily enables the locus of the main undercarriage centre (U) to be
found and hence the path of the undercarriage during the turn to be derived.
Let now O be the guideline centre and R its radius. Assuming that
the steering angle (β) remains unchanged, the instantaneous centre of rotation
of the aircraft at a given time is P and not O. Consequently,
during the short taxi run, the datum point would have departed from the guideline
and covered an arc subtending a small angle equal to:
Figure
A1-10. Example of locus of main undercarriage centre when datum point follows
an arc of circle
Figure
A1-11. Polar angle of aircraft datum point (S)
3. DESIGN OF FILLETS[2]
3.1
Graphic method
3.1.1 The graphic
method consists in determining the fillet by drawing a plan to scale. The scale
should be sufficiently large to ensure an adequate accuracy of the drawing. The
plan can be drawn in selective stages as described below:
a) draw the centre
lines of the taxiways (or runways) to be connected;
b) draw the edges of
the taxiways and/or runways to be laid on the plan;
c) draw the path of
the main undercarriage centre for the most exacting type of aircraft point by
point; and
d) design the fillet.
3.1.2 The path of the
undercarriage centre can be drawn by using the graphs on Figures A1-7 and A1-9
as described in 2.2. Various designs are acceptable for the fillet provided
that the minimum clearance distances shown in Table A1-1 are complied with. To
ensure that these clearance distance requirements are met, a practical method
involves drawing a curve parallel to the path of the main undercarriage centre,
which is located at a distance equal to (T/2 + M), and then drawing the
fillet accordingly.
Example: Design of a
fillet by the graphic method (see Figure A1-12)
Data
(m)
|
Taxiway change of
direction
|
90°
|
Taxiway centre line
radius (R)
|
36.6
|
Taxiway width (X)
|
23.0
|
Aircraft datum
length (d)
|
18.3
|
Aircraft
undercarriage track (T)
|
8.0
|
Safety margin (M)
|
4.0
|
Step 1. From Figure A1-9M for
R/d = 2, extract:
a) the value of the
polar angle for the datum point (S) at the beginning of the turn, the
corresponding steering angle (β) being O;
b) the associated
value or the main undercarriage centre deviation expressed as a decimal part of
the datum length which is 0.235. Now list some values of λ/d and p for a
sequence of θs (e.g. in increments of 20°). Next, draw the datum line
and then plot the points as described in step 3 below.
Step 3. The curves can be
drawn as follows:
a) draw the datum
line as shown in Figure A1-12;
b) for each value of θs
selected in step 1, plot the corresponding point U. For this, locate
point S on the guideline, draw the longitudinal axis of aircraft with
corresponding steering angle p and mark U at a distance d = 18.3
m from S. Using the values of λ/d in step 1, check the accuracy
of the plotting;
c) where the datum
point S again follows a straight line after coming out of the turn,
using the values of λ/d and F/d from step 2, plot the locus of
the undercarriage centre as shown in Figure A1-12;
d) on a perpendicular
dropped from U onto the aircraft longitudinal axis, plot a distance
inwards equal to (T/2 + M) = 4 + 4.0 = 8.0 m for each selected position
of U. The line through these points is the curve parallel to the path of
the main undercarriage centre. This is a theoretical minimum limit for the
fillet.
Note: If the taxiway
could be used by aircraft in both directions, draw the relevant curve as well.
e) select a design of
fillet which can easily be staked out. As a rule it is preferable to choose an
outline made up of straight sections and an arc of a circle. In the case in
question an arc with a radius of 31.7 m is the easiest outline (Figure A1-12).
Step 4. Check the validity of
the design, Figure A1-12:
a) the clearance distance
is 4.0 m in compliance with the minimum recommended in Annex 14, Chapter 3 (see
Table A1-1);
b) the maximum value
(28°) of the steering angle is compatible with the operational limits of the
nose wheel deflection for all the types of aircraft likely to use the
aerodrome.
Figure
A1-12. Graphic method for designing fillet
3.2
Arc-and-tangent method
3.2.1 The path of the
main undercarriage centre of an aircraft during a turn is a complex curve, but
it approximates an arc of a circle and its tangents. A design for a fillet
which closely follows the main undercarriage path and allows for the safety
margin required can be obtained by using:
a) an arc concentric
with the taxiway centre line in order to provide the necessary additional width
of pavement inside the turn; and
b) a tangent at each
end of the arc providing a wedge-shaped end of the fillet to cater for residual
deviation of the main undercarriage.
For drawing the
fillet, it is sufficient to know the radius (r) of the arc and the
length (l) of the wedge-shaped ends of the fillet (see Figure A1-13).
Determination of the
radius of the fillet (r)
3.2.2 The fillet
radius is equal to:
in which
R = radius of taxiway
centre linetaken as guideline
λ max = maximum value
of the deviation of the main undercarriage
M = minimum safety
margin
T = track of main
undercarriage
3.2.3 The maximum
value of the main undercarriage deviation k max depends on the datum length (d),
the radius of curvature of the taxiway centre line (R) and the rate of
change in direction. This maximum value is obtained from Figure A1-14 as a
percentage of the aircraft datum length for any value of ratio R/d included
between 1 and 5.
3.2.4 When the aircraft
datum length (d) is greater than the centre line radius (R), a
construction line should be used with a value for the radius equal to the datum
length, assuming R/d = 1. The points at which this construction line
joins the straight section of the taxiway centre line should be marked for
drawing in the wedge-shaped ends (see 3.2.8).
Figure
A1-13. Design of a fillet by the arc-and-tangent method showing required
clearance distances and calculated fillet
Figure
A1-14. Maximum deviation (k max) of main undercarriage centre
Determination of the
length of the wedge-shaped ends
3.2.5 Filleting is no
longer required at the point where the main undercarriage deviation becomes
less than the maximum deviation permissible without filleting:
where
|
|
|
X
|
=
|
taxiway width
|
|
M
|
=
|
minimum safety margin
|
|
T
|
=
|
track of main
undercarriage
|
The residual
deviation is reached at the end of the turn, when the datum point (S)
has covered along the straight taxiway centre line a distance F given by
the equation (17) in 2.1.8. The length of each wedge-shaped end of the fillet
is therefore:
l
= F - d
3.2.6 Equation (17)
enables F to be expressed as a function of:
a) β, residual
steering angle corresponding to λ, as obtained in 3.2.5 above; and
b) β max, maximum
value of the steering angle during a turn. This value is reached when λ is
equal to λ max, as given by Figure A1-14.
Use of prepared
graphs avoids all calculation. The residual steering angle reached when the
deviation is equal to the maximum permissible deviation without filleting is
obtainable from Figure A1-15. (Figures are given to cover a datum length range
between 12 and 60 m.) The maximum value of the steering angle during a turn is
obtained from Figure A1-16 by reading from the taxiway change of direction to
the ratio R/d and across to obtain the steering angle. Finally, Figure A1-17
enables the values of the steering angle to be converted into displacements
along the straight guideline.
3.2.7 Care should be
taken to ensure that the steering angle does not exceed the maximum nose wheel
angle of the aircraft which are expected to use the aerodrome. If that were the
case, the radius of curvature of the guideline and the size of fillet would
have to be increased.
Note: Because the
datum point does not generally coincide with the nose wheel, this introduces a
slight error. This error, however, is on the safe side.
Drawing the fillet
3.2.8 The required
fillet is obtained as follows:
a) Draw an arc concentric
with the taxiway centre line using radius (r) (or, if necessary, an arc
concentric with the construction line mentioned in 3.2.4).
b) Along the inside
edge of the taxiway, mark Q1 and Q2 at distance l from the
curved section of the guideline, as shown in Figure A1-13.
c) From the points
obtained in b) above, draw tangents to the arc with radius (r).
3.2.9 The
arc-and-tangent method is illustrated in Example 1.
Variant of
arc-and-tangent method
3.2.10 A closer approximation
to the required fillet can be obtained by the use of two fairing lines. The second
point is obtained by recalculating the maximum permissible deviation without
fillet but using a smaller safety margin. The practical method and the result
obtained are illustrated in Example 2.
3.3 Quick reference graph method
3.3.1 The quick reference
graphs enable the fillets of taxiways to be designed in a relatively simple
manner, provided that constant values are given to certain variables:
- the width of the
taxiways and the minimum clearance distance: corresponding to the code letter
of longest runway served;
- datum length and
undercarriage track: corresponding to most demanding type of aircraft involved.
3.3.2 Figure A1-20
has been prepared for a particular type of aircraft, namely the Boeing 747, and
has been plotted on the basis of the following constant values, as recommended
by Annex 14:
X - width of taxiways =
23 m
M - minimum clearance
distance = 4.0 m
and taking as a
guideline the taxiway centre line. In accordance with the provisions of Annex
14, the datum point
selected is located vertically beneath the cockpit. The following constant
values relate to this type of aircraft:
|
B747
|
Parameter
|
(m)
|
|
Datum length of
aircraft
|
(d)
|
27.7
|
Undercarriage track
|
(T)
|
12.8
|
3.3.3 The edge of the
fillet (Figure A1-21) is determined as follows:
Step 1. First the radius of the
fillet arc (r) is determined by plotting the point corresponding to the
change in direction of the taxiway and of the centre line curve radius on graph
A in Figure A1-20. The value obtained by interpolation between the curves drawn
for round values of r is used to draw an arc concentric to that of the
guideline.
Step 2. The distance travelled
(F) from the point when the fillet becomes unnecessary is obtained in
the same manner by means of graph B on Figure A1-20. This gives the distance
from the point where the inside edge of the taxiway becomes straight again.
Step 3. The arc tangents are
drawn so that they intersect the edge of the taxiway at the end of the distance
travelled (F). The line obtained is the required fillet as shown in the
diagram (Figure A1-21).
Figure
A1-15. Steering angle (β) and main undercarriage centre deviation (λ) (Figures
and sloping lines show steering angles)
Figure
A1-16. Increase of steering angle during a turn
Figure
A1-17. Decrease of steering angle on completion of turn
Example
1: Fillet design using arc-and-tangent method (see Figure A1-18)
Figure
A1-18. Typical fillet design, arc-and-tangent method (see Example 1)
Example
2: Compound fillet for longdatum, widetrack aircraft (see Figure A1-19)
Figure
A1-19. Compound fillet for long-datum, wide-track aircraft (see Example 2)
Figure
A1-20. Quick reference graph for Boeing 747 (cockpit over taxiway centre line)
Figure
A1-21. Taxiway fillet diagram
Table
A1-1. Relationship between steering angle and nose wheel deflection angle
Nose
wheel deflection angle (°)
|
X
= 1.0
|
X
= 1.1
|
X
= 1.2
|
X
= 1.3
|
X
= 1.4
|
X
= 1.5
|
X
= 1.6
|
X
= 1.7
|
X
= 1.8
|
X
= 1.9
|
X
= 2.0
|
|
|
|
|
|
|
|
|
|
|
|
|
0.5
|
0.500
|
0.550
|
0.600
|
0.650
|
0.700
|
0.750
|
0.800
|
0.850
|
0.900
|
0.950
|
1.000
|
1.0
|
1.000
|
1.100
|
1.200
|
1.300
|
1.400
|
1.500
|
1.600
|
1.700
|
1.800
|
1.899
|
1.999
|
1.5
|
1.500
|
1.650
|
1.800
|
1.950
|
2.100
|
2.249
|
2.399
|
2.549
|
2.699
|
2.848
|
2.998
|
2.0
|
2.000
|
2.200
|
2.400
|
2.599
|
2.799
|
2.998
|
3.198
|
3.397
|
3.597
|
3.796
|
3.995
|
2.5
|
2.500
|
2.750
|
2.999
|
3.249
|
3.498
|
3.747
|
3.996
|
4.245
|
4.494
|
4.742
|
4.991
|
3.0
|
3.000
|
3.299
|
3.599
|
3.898
|
4.196
|
4.495
|
4.793
|
5.091
|
5.389
|
5.686
|
5.984
|
3.5
|
3.500
|
3.849
|
4.198
|
4.546
|
4.894
|
5.242
|
5.589
|
5.936
|
6.283
|
6.629
|
6.974
|
4.0
|
4.000
|
4.399
|
4.797
|
5.194
|
5.591
|
5.988
|
6.384
|
6.779
|
7.174
|
7.568
|
7.961
|
4.5
|
4.500
|
4.948
|
5.395
|
5.842
|
6.288
|
6.733
|
7.177
|
7.621
|
8.063
|
8.505
|
8.945
|
5.0
|
5.000
|
5.497
|
5.993
|
6.489
|
6.983
|
7.476
|
7.969
|
8.460
|
8.949
|
9.438
|
9.925
|
|
|
|
|
|
|
|
|
|
|
|
|
5.5
|
5.500
|
6.046
|
6.591
|
7.135
|
7.677
|
8.219
|
8.758
|
9.296
|
9.833
|
10.368
|
10.900
|
6.0
|
6.000
|
6.595
|
7.188
|
7.780
|
8.371
|
8.959
|
9.546
|
10.131
|
10.713
|
11.293
|
11.871
|
6.5
|
6.500
|
7.144
|
7.785
|
8.425
|
9.063
|
9.698
|
10.331
|
10.962
|
11.590
|
12.215
|
12.837
|
7.0
|
7.000
|
7.692
|
8.382
|
9.069
|
9.754
|
10.436
|
11.115
|
11.790
|
12.463
|
12.132
|
13.797
|
7.5
|
7.500
|
8.240
|
8.978
|
9.712
|
10.443
|
11.171
|
11.895
|
12.615
|
13.332
|
14.044
|
14.751
|
8.0
|
8.000
|
8.788
|
9.573
|
10.354
|
11.131
|
11.904
|
12.673
|
13.437
|
14.196
|
14.951
|
15.700
|
8.5
|
8.500
|
9.336
|
10.167
|
10.995
|
11.818
|
12.635
|
13.448
|
14.255
|
15.057
|
15.852
|
16.642
|
9.0
|
9.000
|
9.883
|
10.761
|
11.635
|
12.502
|
13.364
|
14.220
|
15.070
|
15.912
|
16.748
|
17.577
|
9.5
|
9.500
|
10.430
|
11.355
|
12.273
|
13.185
|
14.091
|
14.989
|
15.880
|
16.763
|
17.638
|
18.505
|
10.0
|
10.000
|
10.977
|
11.947
|
12.911
|
13.867
|
14.815
|
15.755
|
16.686
|
17.609
|
18.522
|
19.425
|
|
|
|
|
|
|
|
|
|
|
|
|
10.5
|
10.500
|
11.523
|
12.539
|
13.547
|
14.546
|
15.536
|
16.517
|
17.488
|
18.449
|
19.399
|
20.339
|
11.0
|
11.000
|
12.069
|
13.130
|
14.181
|
15.223
|
16.255
|
17.276
|
18.286
|
19.284
|
20.270
|
21.244
|
11.5
|
11.500
|
12.612
|
13.720
|
14.815
|
15.899
|
16.971
|
18.031
|
19.079
|
20.113
|
21.134
|
22.142
|
12.0
|
12.000
|
13.160
|
14.309
|
15.447
|
16.572
|
17.684
|
18.583
|
19.867
|
20.937
|
21.992
|
23.031
|
12.5
|
12.500
|
13.705
|
14.898
|
16.077
|
17.243
|
18.394
|
19.530
|
20.650
|
21.754
|
22.842
|
23.912
|
13.0
|
13.000
|
14.249
|
15.485
|
16.706
|
17.912
|
19.101
|
20.274
|
21.429
|
22.566
|
23.685
|
24.784
|
13.5
|
13.500
|
14.793
|
16.071
|
17.333
|
18.578
|
19.805
|
21.013
|
22.202
|
23.371
|
24.520
|
25.648
|
14.0
|
14.000
|
15.337
|
16.657
|
17.959
|
19.242
|
20.505
|
21.748
|
22.970
|
24.170
|
25.348
|
26.503
|
14.5
|
14.500
|
15.880
|
17.241
|
18.583
|
19.904
|
21.203
|
22.479
|
23.733
|
24.963
|
26.168
|
27.350
|
15.0
|
15.000
|
16.423
|
17.825
|
19.205
|
20.563
|
21.896
|
23.206
|
24.490
|
25.748
|
26.981
|
28.187
|
|
|
|
|
|
|
|
|
|
|
|
|
15.5
|
15.500
|
16.965
|
18.407
|
19.825
|
21.219
|
22.587
|
23.928
|
25.242
|
26.528
|
27.785
|
29.015
|
16.0
|
16.000
|
17.506
|
18.988
|
20.444
|
21.873
|
23.273
|
24.645
|
25.988
|
27.300
|
28.582
|
29.834
|
16.5
|
16.500
|
18.047
|
19.568
|
21.061
|
22.524
|
23.957
|
25.358
|
26.728
|
28.066
|
29.371
|
30.644
|
17.0
|
17.000
|
18.588
|
20.147
|
21.675
|
23.172
|
24.636
|
26.066
|
27.463
|
28.825
|
20.152
|
31.444
|
17.5
|
17.500
|
19.128
|
20.725
|
22.288
|
23.818
|
25.312
|
26.770
|
28.192
|
29.577
|
30.924
|
32.235
|
18.0
|
18.000
|
19.667
|
21.301
|
22.899
|
24.460
|
25.984
|
27.469
|
28.915
|
30.321
|
31.689
|
33.017
|
18.5
|
18.500
|
20.206
|
21.876
|
23.508
|
25.100
|
26.652
|
28.162
|
29.632
|
31.059
|
32.445
|
33.790
|
19.0
|
19.000
|
20.745
|
22.450
|
24.115
|
25.737
|
27.316
|
28.851
|
30.343
|
31.790
|
33.194
|
34.553
|
19.5
|
19.500
|
21.282
|
23.023
|
24.719
|
26.371
|
27.976
|
29.535
|
31.048
|
32.514
|
33.934
|
35.308
|
20.0
|
20.000
|
21.820
|
23.594
|
25.322
|
27.001
|
28.633
|
30.214
|
31.747
|
33.231
|
34.666
|
36.052
|
|
|
|
|
|
|
|
|
|
|
|
|
20.5
|
20.500
|
22.356
|
24.164
|
25.922
|
27.629
|
29.285
|
30.889
|
32.440
|
33.940
|
35.389
|
36.788
|
21.0
|
21.000
|
22.892
|
24.733
|
26.520
|
28.254
|
29.933
|
31.558
|
33.127
|
34.643
|
36.105
|
37.514
|
21.5
|
21.500
|
23.427
|
25.300
|
27.116
|
28.876
|
30.577
|
32.221
|
33.808
|
35.338
|
36.812
|
38.232
|
22.0
|
22.000
|
23.962
|
25.866
|
27.710
|
29.494
|
31.218
|
32.880
|
34.483
|
36.026
|
37.512
|
38.940
|
22.5
|
22.500
|
24.496
|
26.430
|
28.301
|
30.109
|
31.854
|
33.534
|
35.152
|
36.708
|
38.203
|
39.639
|
23.0
|
23.000
|
25.029
|
26.993
|
28.891
|
30.722
|
32.485
|
34.183
|
35.814
|
37.283
|
38.886
|
40.330
|
23.5
|
23.500
|
25.561
|
27.554
|
29.478
|
31.330
|
33.113
|
34.826
|
36.471
|
38.049
|
29.562
|
41.011
|
24.0
|
24.000
|
26.093
|
28.114
|
30.062
|
31.936
|
33.737
|
35.465
|
37.122
|
38.709
|
40.229
|
41.684
|
24.5
|
24.500
|
26.625
|
28.673
|
30.644
|
32.539
|
34.356
|
36.098
|
37.766
|
39.362
|
40.889
|
42.348
|
25.0
|
25.000
|
25.155
|
29.230
|
31.224
|
33.128
|
34.971
|
36.726
|
38.405
|
40.009
|
41.540
|
43.003
|
|
|
|
|
|
|
|
|
|
|
|
|
25.5
|
25.500
|
27.685
|
29.786
|
31.802
|
33.734
|
35.582
|
37.349
|
39.037
|
40.648
|
42.185
|
43.650
|
26.0
|
26.000
|
28.214
|
30.340
|
32.377
|
34.326
|
36.189
|
37.967
|
39.664
|
41.281
|
42.821
|
44.288
|
26.5
|
26.500
|
28.742
|
30.892
|
32.950
|
34.916
|
36.792
|
38.580
|
40.284
|
41.906
|
43.450
|
44.919
|
27.0
|
27.000
|
29.270
|
31.443
|
33.520
|
35.502
|
37.390
|
39.188
|
40.899
|
42.525
|
33.071
|
45.541
|
27.5
|
27.500
|
29.796
|
31.992
|
34.088
|
36.084
|
37.985
|
39.791
|
41.508
|
43.138
|
44.685
|
46.155
|
28.0
|
28.000
|
30.323
|
32.540
|
34.653
|
36.664
|
38.575
|
40.389
|
42.111
|
43.744
|
45.292
|
46.760
|
28.5
|
28.500
|
30.848
|
33.086
|
35.216
|
37.240
|
39.161
|
40.982
|
42.708
|
44.343
|
45.892
|
47.358
|
29.0
|
29.000
|
21.372
|
22.631
|
35.777
|
37.813
|
39.742
|
41.570
|
43.299
|
44.936
|
46.484
|
47.949
|
29.5
|
29.500
|
31.896
|
34.174
|
36.335
|
38.382
|
40.320
|
42.153
|
43.885
|
45.522
|
47.069
|
48.531
|
30.0
|
30.000
|
32.419
|
34.715
|
36.890
|
38.948
|
40.893
|
42.731
|
44.465
|
46.102
|
47.648
|
49.107
|
|
|
|
|
|
|
|
|
|
|
|
|
30.5
|
30.500
|
32.941
|
35.255
|
37.443
|
39.511
|
41.463
|
43.304
|
45.039
|
46.676
|
48.219
|
49.674
|
31.0
|
31.000
|
33.463
|
35.793
|
37.994
|
40.071
|
42.028
|
43.872
|
45.608
|
47.244
|
48.784
|
50.235
|
31.5
|
31.500
|
33.983
|
36.329
|
38.542
|
40.627
|
42.589
|
44.435
|
46.172
|
47.805
|
49.342
|
50.788
|
32.0
|
32.000
|
34.503
|
36.864
|
39.088
|
41.180
|
43.146
|
44.994
|
46.730
|
48.361
|
49.893
|
51.334
|
32.5
|
32.500
|
35.022
|
37.397
|
39.631
|
41.730
|
43.700
|
45.548
|
47.282
|
48.910
|
50.438
|
51.874
|
33.0
|
33.000
|
35.540
|
37.929
|
40.172
|
42.276
|
44.249
|
46.097
|
47.810
|
49.454
|
50.077
|
52.406
|
33.5
|
33.500
|
36.057
|
38.459
|
40.170
|
42.819
|
44.794
|
46.642
|
48.372
|
49.991
|
51.509
|
52.932
|
34.0
|
34.000
|
36.574
|
38.987
|
41.246
|
43.359
|
45.335
|
47.182
|
48.908
|
50.524
|
52.035
|
53.451
|
34.5
|
34.500
|
37.090
|
39.514
|
41.780
|
43.896
|
45.872
|
47.717
|
49.440
|
51.050
|
52.555
|
53.964
|
35.0
|
35.000
|
37.604
|
40.039
|
42.311
|
44.430
|
46.406
|
48.248
|
49.967
|
51.571
|
53.069
|
54.470
|
|
|
|
|
|
|
|
|
|
|
|
|
35.5
|
35.500
|
38.119
|
40.562
|
42.839
|
44.960
|
46.935
|
48.775
|
50.488
|
52.086
|
53.578
|
54.971
|
36.0
|
36.000
|
38.632
|
41.084
|
43.365
|
45.467
|
47.461
|
49.297
|
51.005
|
52.596
|
54.080
|
55.465
|
36.5
|
36.500
|
39.144
|
41.604
|
43.889
|
46.011
|
47.983
|
49.184
|
51.517
|
53.101
|
54.577
|
55.953
|
37.0
|
37.000
|
39.656
|
42.122
|
44.410
|
46.532
|
48.501
|
50.328
|
52.024
|
53.601
|
55.068
|
56.435
|
37.5
|
37.500
|
40.166
|
42.639
|
44.929
|
47.050
|
49.015
|
50.637
|
52.526
|
54.095
|
55.553
|
56.911
|
38.0
|
38.000
|
40.676
|
43.154
|
45.445
|
47.565
|
49.526
|
51.341
|
53.024
|
54.584
|
56.034
|
57.382
|
38.5
|
38.500
|
41.185
|
43.667
|
45.960
|
48.077
|
50.003
|
51.842
|
53.517
|
55.068
|
56.509
|
57.847
|
39.0
|
39.000
|
41.693
|
44.179
|
46.471
|
48.585
|
50.537
|
52.339
|
54.005
|
55.548
|
56.978
|
58.307
|
39.5
|
39.500
|
42.201
|
44.689
|
46.981
|
49.091
|
51.036
|
52.831
|
54.489
|
56.022
|
57.443
|
58.761
|
40.0
|
40.000
|
42.707
|
45.198
|
47.487
|
49.594
|
51.533
|
53.320
|
54.968
|
56.492
|
57.902
|
59.210
|
|
|
|
|
|
|
|
|
|
|
|
|
40.5
|
40.500
|
43.213
|
45.704
|
47.992
|
50.094
|
52.026
|
53.804
|
55.443
|
56.957
|
58.357
|
59.654
|
41.0
|
41.000
|
43.719
|
46.210
|
48.494
|
50.590
|
52.515
|
54.285
|
55.914
|
57.418
|
58.807
|
60.093
|
41.5
|
41.500
|
44.222
|
46.713
|
48.994
|
51.084
|
53.001
|
54.761
|
56.381
|
57.874
|
59.252
|
60.527
|
42.0
|
42.000
|
44.725
|
47.215
|
49.492
|
51.575
|
53.483
|
55.234
|
56.843
|
58.325
|
59.692
|
60.956
|
42.5
|
42.500
|
45.227
|
47.716
|
49.988
|
52.063
|
53.963
|
55.703
|
57.302
|
58.772
|
60.128
|
61.381
|
43.0
|
43.000
|
45.729
|
48.215
|
50.481
|
52.549
|
54.439
|
56.169
|
57.756
|
59.215
|
60.559
|
61.800
|
43.5
|
43.500
|
46.229
|
48.712
|
50.972
|
53.031
|
54.911
|
56.631
|
58.206
|
59.654
|
60.986
|
62.216
|
44.0
|
44.000
|
46.729
|
49.208
|
51.461
|
53.511
|
55.381
|
57.089
|
58.653
|
60.088
|
61.409
|
62.626
|
44.5
|
44.500
|
47.228
|
49.702
|
51.947
|
53.988
|
55.847
|
57.543
|
59.096
|
60.519
|
61.827
|
63.033
|
45.0
|
45.000
|
47.726
|
50.194
|
52.431
|
54.462
|
56.310
|
57.995
|
59.534
|
60.945
|
62.241
|
63.435
|
|
|
|
|
|
|
|
|
|
|
|
|
45.5
|
45.500
|
48.224
|
50.685
|
52.914
|
54.934
|
56.770
|
58.442
|
59.970
|
61.368
|
62.652
|
63.833
|
46.0
|
46.000
|
48.720
|
51.175
|
53.394
|
55.403
|
57.227
|
58.887
|
60.401
|
61.878
|
63.058
|
64.227
|
46.5
|
46.500
|
49.216
|
51.663
|
53.872
|
55.869
|
57.681
|
59.328
|
60.829
|
62.202
|
63.460
|
64.616
|
47.0
|
47.000
|
49.711
|
52.149
|
54.347
|
56.333
|
58.132
|
59.765
|
61.254
|
62.613
|
63.858
|
65.002
|
47.5
|
47.500
|
50.205
|
52.634
|
54.821
|
56.794
|
58.850
|
60.200
|
61.675
|
63.021
|
64.253
|
65.384
|
48.0
|
48.000
|
50.698
|
53.118
|
55.293
|
57.253
|
59.025
|
60.631
|
62.092
|
63.425
|
64.644
|
65.763
|
48.5
|
48.500
|
51.190
|
53.600
|
55.762
|
57.709
|
59.467
|
61.059
|
62.506
|
63.825
|
65.031
|
66.137
|
49.0
|
49.000
|
51.682
|
54.080
|
56.230
|
58.163
|
59.907
|
61.485
|
62.917
|
64.222
|
65.415
|
66.508
|
49.5
|
49.500
|
51.173
|
54.559
|
56.696
|
58.614
|
60.343
|
61.907
|
63.325
|
64.616
|
65.795
|
66.876
|
50.0
|
50.000
|
52.663
|
55.037
|
57.159
|
59.063
|
60.777
|
62.326
|
63.730
|
65.007
|
66.172
|
67.240
|
|
|
|
|
|
|
|
|
|
|
|
|
50.5
|
50.500
|
53.152
|
55.513
|
57.621
|
59.510
|
61.209
|
62.742
|
64.131
|
65.394
|
66.546
|
67.600
|
51.0
|
51.000
|
53.641
|
55.988
|
58.081
|
59.954
|
61.637
|
63.155
|
64.530
|
65.778
|
66.916
|
67.957
|
51.5
|
51.500
|
54.128
|
56.461
|
58.539
|
60.396
|
62.063
|
63.566
|
64.925
|
66.159
|
67.283
|
68.311
|
52.0
|
52.000
|
54.615
|
56.933
|
58.995
|
60.836
|
62.487
|
63.974
|
65.317
|
66.537
|
67.647
|
68.662
|
52.5
|
52.500
|
55.102
|
57.404
|
59.449
|
61.273
|
62.908
|
64.379
|
65.707
|
66.912
|
68.008
|
69.010
|
53.0
|
53.000
|
55.587
|
57.873
|
59.901
|
61.709
|
63.326
|
64.781
|
66.094
|
67.284
|
68.366
|
69.355
|
53.5
|
53.500
|
56.072
|
58.341
|
60.351
|
62.142
|
63.743
|
65.181
|
66.478
|
67.653
|
68.721
|
69.697
|
54.0
|
54.000
|
56.556
|
58.807
|
60.800
|
62.573
|
64.156
|
65.578
|
66.859
|
68.019
|
69.074
|
70.035
|
54.5
|
54.500
|
57.039
|
59.272
|
61.247
|
63.001
|
64.568
|
65.972
|
67.238
|
68.383
|
69.423
|
70.371
|
55.0
|
55.000
|
57.521
|
59.736
|
61.692
|
63.428
|
64.977
|
66.364
|
67.614
|
68.744
|
69.770
|
70.705
|
|
|
|
|
|
|
|
|
|
|
|
|
55.5
|
55.500
|
58.003
|
60.199
|
62.136
|
63.358
|
65.383
|
66.754
|
67.987
|
69.102
|
70.114
|
71.035
|
56.0
|
56.000
|
58.484
|
60.660
|
62.577
|
64.276
|
65.788
|
67.141
|
68.358
|
69.458
|
70.455
|
71.363
|
56.5
|
56.500
|
58.964
|
61.120
|
63.017
|
64.696
|
66.190
|
67.526
|
68.727
|
69.811
|
70.794
|
71.688
|
57.0
|
57.000
|
59.444
|
61.579
|
63.456
|
65.115
|
66.590
|
67.909
|
69.093
|
70.161
|
71.130
|
72.011
|
57.5
|
57.500
|
59.923
|
62.037
|
63.893
|
65.532
|
66.988
|
68.289
|
69.457
|
70.510
|
71.464
|
72.331
|
58.0
|
58.000
|
60.401
|
62.493
|
64.328
|
65.947
|
67.384
|
68.667
|
69.818
|
70.856
|
71.795
|
72.649
|
58.5
|
58.500
|
60.878
|
62.948
|
64.762
|
66.360
|
67.778
|
69.043
|
70.177
|
71.199
|
72.124
|
72.965
|
59.0
|
59.000
|
61.355
|
63.402
|
65.194
|
66.772
|
68.170
|
69.417
|
70.534
|
71.540
|
72.451
|
73.278
|
59.5
|
59.500
|
61.831
|
63.855
|
65.624
|
67.181
|
68.360
|
69.789
|
70,889
|
71.879
|
72.775
|
73.589
|
60.0
|
60.000
|
62.307
|
64.307
|
66.053
|
67.589
|
68.948
|
70.158
|
71.242
|
72.216
|
73.098
|
73.898
|
|
|
|
|
|
|
|
|
|
|
|
|
60.5
|
60.500
|
62.781
|
64.757
|
64.481
|
67.995
|
69.334
|
70.526
|
71.592
|
72.551
|
73.418
|
74.205
|
61.0
|
61.000
|
63.256
|
65.207
|
66.907
|
68.400
|
69.719
|
70.892
|
71.941
|
72.884
|
73.736
|
74.509
|
61.5
|
61.500
|
63.729
|
65.655
|
67.332
|
68.802
|
70.101
|
71.255
|
72.287
|
73.214
|
74.052
|
74.812
|
62.0
|
62.000
|
64.202
|
66.102
|
67.775
|
69.204
|
70.482
|
71.617
|
72.632
|
73.543
|
74.366
|
75.112
|
62.5
|
62.500
|
64.674
|
66.549
|
68.177
|
69.603
|
70.861
|
71.977
|
72.975
|
73.870
|
74.678
|
75.411
|
63.0
|
63.000
|
65.146
|
66.994
|
68.598
|
70.001
|
71.238
|
72.336
|
73.315
|
74.195
|
74.988
|
75.707
|
63.5
|
63.500
|
65.617
|
67.438
|
69.017
|
70.398
|
71.614
|
72.692
|
73.654
|
74.518
|
75.296
|
76.002
|
64.0
|
64.000
|
66.088
|
67.881
|
69.435
|
70.793
|
71.988
|
73.047
|
73.992
|
74.839
|
75.603
|
76.295
|
64.5
|
64.500
|
66.558
|
68.323
|
69.852
|
71.186
|
72.360
|
73.400
|
74.327
|
75.159
|
75.908
|
76.586
|
65.0
|
65.000
|
67.027
|
68.764
|
70.267
|
71.578
|
72.731
|
73.752
|
74.661
|
75.476
|
76.211
|
76.876
|
|
|
|
|
|
|
|
|
|
|
|
|
65.5
|
65.500
|
67.496
|
69.205
|
70.681
|
71.969
|
73.100
|
74.102
|
74.993
|
75.792
|
76.512
|
77.164
|
66.0
|
66.000
|
67.964
|
69.644
|
71.095
|
72.358
|
73.468
|
74.450
|
75.324
|
76.107
|
76.812
|
77.450
|
66.5
|
66.500
|
68.432
|
70.082
|
71.506
|
72.746
|
73.834
|
74.797
|
75.653
|
76.420
|
77.110
|
77.734
|
67.0
|
67.000
|
68.899
|
70.520
|
71.917
|
73.133
|
74.199
|
75.142
|
75.980
|
76.731
|
77.406
|
78.017
|
67.5
|
67.500
|
69.336
|
70.956
|
72.327
|
73.518
|
74.563
|
75.486
|
76.306
|
77.041
|
77.702
|
78.299
|
68.0
|
68.000
|
69.832
|
71.392
|
72.735
|
73.902
|
74.925
|
75.828
|
76.631
|
77.349
|
77.995
|
78.579
|
68.5
|
68.500
|
70.298
|
71.827
|
73.143
|
74.285
|
75.286
|
76.169
|
76.954
|
77.656
|
78.287
|
78.858
|
69.0
|
69.000
|
70.763
|
72.251
|
73.549
|
74.667
|
75.646
|
76.509
|
77.276
|
77.962
|
78.587
|
79.135
|
69.5
|
69.500
|
71.227
|
72.695
|
73.955
|
75.048
|
76.004
|
76.847
|
77.596
|
78.266
|
78.867
|
79.411
|
70.0
|
70.000
|
71.692
|
73.127
|
74.359
|
75.427
|
76.361
|
77.184
|
77.915
|
78.569
|
79.156
|
79.686
|
|
|
|
|
|
|
|
|
|
|
|
|
70.5
|
70.500
|
72.155
|
73.559
|
74.762
|
75.805
|
76.717
|
77.520
|
78.233
|
78.870
|
79.442
|
79.959
|
71.0
|
71.000
|
72.619
|
73.900
|
75.165
|
76.182
|
77.072
|
77.855
|
78.550
|
79.171
|
79.728
|
80.232
|
71.5
|
71.500
|
73.081
|
74.420
|
75.566
|
76.559
|
77.425
|
78.188
|
78.865
|
79.470
|
80.012
|
80.503
|
72.0
|
72.000
|
73.544
|
74.850
|
75.967
|
76.934
|
77.778
|
78.521
|
79.180
|
79.768
|
80.296
|
80.772
|
72.5
|
72.500
|
74.006
|
75.278
|
76.367
|
77.309
|
78.129
|
78.852
|
79.493
|
80.065
|
80.578
|
81.041
|
73.0
|
73.000
|
74.467
|
75.707
|
76.766
|
77.681
|
78.480
|
79.182
|
79.805
|
80.360
|
80.859
|
81.309
|
73.5
|
73.500
|
74.929
|
76.134
|
77.164
|
78.053
|
78.829
|
79.511
|
80.116
|
80.655
|
81.139
|
81.575
|
74.0
|
74.000
|
75.389
|
76.561
|
77.561
|
78.425
|
79.178
|
79.840
|
80.426
|
80.949
|
81.418
|
81.841
|
74.5
|
74.500
|
75.850
|
76.987
|
77.958
|
78.795
|
79.525
|
80.167
|
80.735
|
81.241
|
81.696
|
82.106
|
75.0
|
75.000
|
76.310
|
77.413
|
78.354
|
79.165
|
79.872
|
80.493
|
81.043
|
81.533
|
81.973
|
82.369
|
|
|
|
|
|
|
|
|
|
|
|
|
75.5
|
75.500
|
76.770
|
77.838
|
78.749
|
79.534
|
80.218
|
80.818
|
81.350
|
81.824
|
82.249
|
82.632
|
76.0
|
76.000
|
77.229
|
78.262
|
79.143
|
79.902
|
80.563
|
81.143
|
81.656
|
82.114
|
82.524
|
82.894
|
76.5
|
76.500
|
77.688
|
78.686
|
79.537
|
80.269
|
80.907
|
81.466
|
81.962
|
82.403
|
82.798
|
83.155
|
77.0
|
77.000
|
78.147
|
79.110
|
79.930
|
80.636
|
81.250
|
81.789
|
82.266
|
82.691
|
83.072
|
83.415
|
77.5
|
77.500
|
78.605
|
79.533
|
80.322
|
81.002
|
81.593
|
82.111
|
82.570
|
82.979
|
83.345
|
83.675
|
78.0
|
78.000
|
79.063
|
79.955
|
80.714
|
81.367
|
81.935
|
82.433
|
82.873
|
83.265
|
83.617
|
83.933
|
78.5
|
78.500
|
79.521
|
80.377
|
81.105
|
81.731
|
82.276
|
82.753
|
83.175
|
83.551
|
82.888
|
84.192
|
79.0
|
79.000
|
79.979
|
80.799
|
81.496
|
82.095
|
82.616
|
83.073
|
83.477
|
83.837
|
84.159
|
84.449
|
79.5
|
79.500
|
80.436
|
81.220
|
81.886
|
82.459
|
82.956
|
83.392
|
83.778
|
84.121
|
84.429
|
84.706
|
80.0
|
80.000
|
80.893
|
81.641
|
82.276
|
82.822
|
83.296
|
83.711
|
84.078
|
84.405
|
84.698
|
84.962
|
|
|
|
|
|
|
|
|
|
|
|
|
80.5
|
80.500
|
81.350
|
82.061
|
82.665
|
83.184
|
83.634
|
84.029
|
84.378
|
84.689
|
84.967
|
85.217
|
81.0
|
81.000
|
81.807
|
82.481
|
83.054
|
83.545
|
83.972
|
84.347
|
84.677
|
84.971
|
85.235
|
85.472
|
81.5
|
81.500
|
82.263
|
82.901
|
83.442
|
83.907
|
84.310
|
84.664
|
84.976
|
85.254
|
85.502
|
85.726
|
82.0
|
82.000
|
82.719
|
83.320
|
83.830
|
84.287
|
84.647
|
84.980
|
85.274
|
85.536
|
85.770
|
85.980
|
82.5
|
82.500
|
83.175
|
83.739
|
84.217
|
84.628
|
84.984
|
85.296
|
85.572
|
85.817
|
86.036
|
86.234
|
83.0
|
83.000
|
83.631
|
84.156
|
84.604
|
84.988
|
85.320
|
85.612
|
85.869
|
86.098
|
86.302
|
86.487
|
83.5
|
83.500
|
84.087
|
84.576
|
84.991
|
85.347
|
85.656
|
85.927
|
86.166
|
86.378
|
86.568
|
86.740
|
84.0
|
84.000
|
84.542
|
84.994
|
85.378
|
85.707
|
85.992
|
86.242
|
86.462
|
86.658
|
86.834
|
86.992
|
84.0
|
84.000
|
84.542
|
84.994
|
85.378
|
85.707
|
85.992
|
86.242
|
86.462
|
86.658
|
86.834
|
86.992
|
84.5
|
84.500
|
84.997
|
85.412
|
85.764
|
86.066
|
86.327
|
86.556
|
86.758
|
86.938
|
87.099
|
87.244
|
85.0
|
85.000
|
85.453
|
85.830
|
86.150
|
86.424
|
86.662
|
86.870
|
87.054
|
87.217
|
87.364
|
87.495
|
|
|
|
|
|
|
|
|
|
|
|
|
85.5
|
85.500
|
85.908
|
86.248
|
86.536
|
86.782
|
86.997
|
87.184
|
87.349
|
87.496
|
87.628
|
87.747
|
86.0
|
86.000
|
86.363
|
86.665
|
86.921
|
87.141
|
87.331
|
87.498
|
87.645
|
87.775
|
87.892
|
87.998
|
86.5
|
86.500
|
86.817
|
87.082
|
87.306
|
87.498
|
87.665
|
87.811
|
87.940
|
88.054
|
88.156
|
88.248
|
87.0
|
87.000
|
87.272
|
87.499
|
87.691
|
87.856
|
87.999
|
88.124
|
88.234
|
88.332
|
88.420
|
88.499
|
87.5
|
87.500
|
87.727
|
87.916
|
88.076
|
88.214
|
88.333
|
88.437
|
88.529
|
88.611
|
88.684
|
88.749
|
88.0
|
88.000
|
88.182
|
88.333
|
88.461
|
88.571
|
88.666
|
88.750
|
88.823
|
88.889
|
88.947
|
89.000
|
88.5
|
88.500
|
88.636
|
88.750
|
88.846
|
88.928
|
89.000
|
89.062
|
89.118
|
89.167
|
89.210
|
89.250
|
89.0
|
89.000
|
89.091
|
89.167
|
89.231
|
89.286
|
89.333
|
89.375
|
89.412
|
89.444
|
89.474
|
89.500
|
89.5
|
89.500
|
89.545
|
89.583
|
89.615
|
89.643
|
89.667
|
89.687
|
89.706
|
89.722
|
89.737
|
89.750
|
90.0
|
90.000
|
90.000
|
90.000
|
90.000
|
90.000
|
90.000
|
90.000
|
90.000
|
90.000
|
90.000
|
90.000
|
APPENDIX 2
JET BLAST AND BLAST FENCE CONSIDERATIONS
Introduction
1. “Jet blast” and
“prop wash” are terms used to describe the air currents that emanate from the
operation of jet and propeller engines, respectively. The design of ground
facilities, buildings and pavements must take into account the impact of the
forces that result from these air movements. Prior to the introduction of jet turbine
engines, very little attention was focused, when planning facilities and
pavements, on the detrimental effects of propeller wash. Service and
maintenance areas were sometimes equipped with fences to deflect winds because
of the close aircraft spacings used in these areas, but the design of aprons and
terminal buildings was generally not influenced by propeller wash considerations.
The introduction of the jet engine and the technological improvements that have
been made towards increasing the power and efficiency of these engines have
brought about a significant increase in blast velocities and, therefore, the need
to design facilities to accommodate the wind forces associated with these
velocities. This appendix describes the nature of these forces in terms of
their magnitude and location and presents concepts in the location and design
of blast fences and pavements which may be required at aerodromes to mitigate
these wind forces.
Related
effects
2. In addition to
high wind velocities, the noise, heat and fumes from jet engine exhaust should
also be anticipated when planning aerodrome facilities. However, the areas
where the effects of jet engine exhaust are detrimental to personnel or
buildings are usually unoccupied because of the high blast air velocities. The
potential for sand, gravel or other loose objects to become projectiles and be
thrown for great distances or drawn into engines must be mitigated. Such flying
objects can injure personnel and damage equipment, facilities and other
aircraft.
Design
thrust levels
3. Three levels of
engine thrust are commonly used to determine the critical velocities for use in
building and pavement design: idle thrust, breakaway thrust and maximum
continuous thrust (take-off thrust). Nearly all facilities adjacent to aircraft
movement areas will be subjected to at least idle thrust from the engines on the
critical design aircraft. Breakaway thrust is the level of thrust needed to initiate
aircraft taxi movement and is generally 50 to 60 per cent of maximum continuous
thrust. Areas typically designed for breakaway thrust may include terminal
buildings, apron and taxiway shoulders, holding bays and all pavements except
for the runways. Aircraft use maximum continuous thrust during take-off, and
thus the runway pavement, shoulders and ends (blast pads) would be designed for
this thrust level.
Threshold
velocities
4. Jet blast velocities
above 56 km/h are considered to be undesirable for personal comfort or for the
operation of vehicles or other equipment on the movement area. Buildings can be
designed to withstand much higher velocities, but the extra cost of
construction needed to handle wind pressures above those normally used in building
design may become prohibitive. Buildings are normally designed to handle winds
of 130 to 200 km/h, depending upon locality. If design velocities are increased
above this level because of blast, then the building structural frame and
architectural facades will need to be strengthened accordingly. The tradeoff
between increasing the cost of the building and other solutions to lower the
blast velocities striking the building (such as erecting blast fences or increasing
the apron size) must be examined for any given aerodrome.
BLAST
VELOCITIES AND PRESSURES Velocity contours
5. Information on
specific jet engine exhaust velocities, including lateral and vertical
contours, for a given aircraft model is given in the Airplane Characteristics For
Airport Planning document prepared for most aircraft models by the aircraft manufacturer.
These documents are generally available from the manufacturers upon written
request. Lateral and vertical contours for the B737-8, B747-8, MD-11 and
B777-300ER at idle, breakaway and take-off power are shown in Figures A2-1
through A2-4. Table A2-1 shows the distance from the rear of an aircraft at
which the blast velocity has been reduced to 56 km/h, the threshold for personal
comfort, operation of vehicles or other equipment, for each of the four
commercial aircraft types and thrust levels.
Blast
pressure
6. The forces
generated by jet blast can be calculated using formulas of the general wind
pressure form P = C X V, where P is the pressure, C is a
shape factor and V is the square of the wind velocity normal to the
surface. Figure A2-5 presents a graph of pressure versus blast velocity and
includes the general formula in terms of the units given for velocity and
pressure. The upper curve gives the pressure on a flat surface oriented
perpendicular to the direction of the blast which yields the greatest possible
pressure. The lower curve is for a more aerodynamically shaped surface with a
shape factor coefficient 70 per cent as great as the flat surface coefficient.
The total force on a curved surface is found by multiplying the pressure by the
area of the surface projected onto a plane perpendicular to the direction of
the blast. Because pressure is a function of the square of the velocity, a doubling
of velocity causes a quadrupling of pressure. On the other hand, a relatively
small increase in the distance between the rear of an aircraft and buildings,
equipment or personnel will yield a significant reduction in the pressure exerted
by the blast on the object. Also shown on Figure A2-5 are representative blast velocities
from Table A2-2 to show the relationship with the personal comfort level and
the typical building design wind pressure.
Other
considerations
7. Several additional
factors which further define the nature of blast are as follows:
a) jet blast is
irregular and turbulent in nature. When designing windows and elements of
buildings less than 1.4 m, the vibrations caused by the cyclicality of blast
velocities should be taken into account;
b) the height of the
centre line of blast depends uponthe height and angle of the engines on the
aircraft;
c) except for
long-bodied aircraft, the lateral spreadof blast winds is generally confined
within the wing tips of the aircraft for a significant distance behind the
aircraft (see notes on Figures A2-1 through A2-4); and
d) ambient winds can
increase, decrease or shift the engine blast, depending upon the direction of the
wind. Allowance can be made for this factor by adding an ambient wind velocity
(appropriate for a given locality) to the blast velocity.
BLAST
FENCES
Application
8. Blast fences are
used at aerodromes to reduce or eliminate the detrimental effects of blast by
deflecting the high air velocities, heat, fumes and noise associated with
blast. The application of either fences or screens becomes necessary when it is
impractical to provide a safe, reasonable separation between aircraft engines
and people, buildings or other objects on the aerodrome. Aerodrome locations
requiring blast fences are indicated in Figure A2-6.
Planning
criteria
9. The aircraft types
and their possible movement patterns must be established when planning a system
of blast fences for a new or existing aerodrome. Each segment of the aircraft
movement area, including the aprons, taxiways, holding bays and runways, must
be analysed to determine the magnitude and all possible orientations for blast
in that particular location. For a new aerodrome, this information can be used
as one of the many criteria needed to determine appropriate building restriction
lines for the location of future facilities. For an existing aerodrome, this
information can be used to determine where new blast fences should be located
or modified because of the introduction of larger jets, the addition of new
runways or taxiways, or a change in aircraft ground movement patterns.
Blast
fences in apron areas
10. The type of apron
movement pattern used by aircraft entering or exiting aircraft stands is a
critical factor in determining the need for and location of blast fences.
Figure A2-7 illustrates an example of the fence requirements for a
self-manoeuvring aircraft stand and for the same stand using a taxi-in, push-out
procedure. Because the aircraft on this self- manoeuvring stand must make a
full 180° turn within the apron area under breakaway blast conditions, all
areas along the public access road, service road and between aircraft parking
positions can be subjected to excessive blast. As a result, fences will be
required in all of these locations unless sufficient separation can be provided
between the aircraft positions and the affected area. The situation becomes
more complicated if passengers must walk on the apron to board the aircraft.
Additional precautions may be required to protect them from the blast of
aircraft entering or leaving adjacent stands. Had the apron been designed so as
to use a nose- in, push-out procedure and nose-loading devices, only a blast
fence along the public access road would be needed. This type of apron system has
become more common at larger aerodromes serving the latest generation of jets
because of the increasing problem with blast in the newer jets and the need to
reduce the cost and complexity of accommodating blast on self-manoeuvring
stands.
Blast
fences in off-apron areas
11. Blast fences
should also be used anywhere on an aerodrome where blast could cause a danger
to personnel or inflict damage to buildings, equipment or other aircraft. They
are often used along taxiways and near taxiway crossovers to protect hangars or
terminal facilities where the aircraft can turn through 90 or 180 degrees.
Another critical location is the area off the end of the runway, centred about
the runway centre line, which should be examined closely because this area is
subjected to the aircraft’s maximum continuous thrust on take-off. Roads or
railways intersecting these areas may need the protection of blast fences. Of
course the use of blast fences in any location should not cause a hazard to the
movement of aircraft or ground vehicles (see Figure A2-7).
Other
types of blast protection
12. Although the use
of manufactured blast fences is effective, blast protection may be gained using
other methods and materials. Any obstruction, either natural or constructed,
will afford some level of protection. Hedges, bushes and trees can also help
attenuate sound. Tall hedges may be used with great advantage in some cases
such as around engine run-up areas.
DESIGN
OF BLAST FENCES
13. Though often
vital to the safe operation of an aerodrome, blast fences are rarely the
starting point in the design of apron or aerodrome facilities. Instead, they
are located only after the basic aerodrome layout has been determined and where
it is most convenient with regard to aircraft or ground vehicle movements. In
addition, the appearance of the fences will often be dictated by overall
architectural considerations. For these reasons, the design of blast fences is
difficult to standardize and often requires custom design.
Types
of fencing
14. Fencing material
can be either concrete or metal. Most premanufactured fences are metal.
Concrete deflectors generally require much less maintenance. Louvred fences
deflect the blast through their full height and therefore are subjected to
lower wind forces than a solid fence for the same blast conditions. Baffles,
perforations, louvres and corrugations can be used singly or in combination to
most effectively reduce or eliminate blast effects behind the fence. Several
types of blast fences are illustrated in Figure A2-8.
Structural
design of blast fences
15. Both custom-designed
and premanufactured blast fences require a thorough structural analysis to
ensure that the fence used has adequate strength to carry the wind forces. The
procedures which would be used in a typical design are summarized in the
following paragraphs.
a) Gross wind pressure.
For a given fence location, the worst possible blast velocity and pressure
from the aircraft to be served at the aerodrome can be obtained from the
aircraft manufacturers.
b) Height of fence.
The blast fence should, at a minimum, be high enough to deflect the centre
portion of the blast. This height is an aircraft-dependent variable and should
be used in conjunction with the calculation of pressure to establish the
critical fence section.
c) Shape and type of
fence. The shape of the fence, whether curved, straight, angled or
vertical, and the type of fence, such as solid or louvred, will determine the
net wind pressure on the wall. Aerodynamically designed shapes and the use of
openings in the fences will reduce the gross pressure requirements.
d) Analysis of
forces. Given the net pressure on the wall, its height, the location of
other supports such as braces or struts, and the type of materials used, the
sizes and strengths of the members required for the wall can be determined. This
procedure applies to premanufactured fence sections as well as custom- designed
sections.
e) Foundations. The
size and shape of the supporting foundation will depend on the factors listed
in d) as well as the type of soils present in the area. Therefore, foundations,
by necessity, are custom-designed.
BLAST
PADS AND SHOULDERS
16. Shoulders
adjacent to taxiways and runways and particularly the areas off the ends of the
runways may be subjected to large blast forces. In fact, drag and uplift
forces, caused by high-energy jet exhaust from turbine-engined aircraft, at
10.5 m behind the exhaust nozzle of an engine operating at maximum thrust, can
raise boulders 0.6 m in diameter completely off the ground. The forces causing
such erosion decrease rapidly with distance; beyond about 360 m from the engine
of a long-bodied aircraft, they affect only sand and finer cohesionless soils.
Blast pads and shoulder paving should be used as needed to mitigate the
detrimental effects of these factors. Guidance on treatment of shoulders and
blast pads is given in Chapter 1, 1.6.10.
Dimensions
17. Blast pads should
have a width equal to the width of the runway plus shoulders. The length of
blast pads may be determined as follows:
- For aircraft such
as Boeing 747 and A380, a blast pad length of at least 120 m is recommended;
- For smaller
aircraft, a blast pad length of 60 m is recommended.
Drainage
18. Drainage
capability should be maintained or improved in the affected areas. Where pavement
edge drop-off and five per cent transverse slope are present in existing turf
areas, they may be retained in the new paved surface. It is recommended that
courses of sufficient depth be provided to maintain the positive drainage of
granular base or sub-base courses under the runway pavement. An alternative is
the provision of subdrains at the pavement edge. A sufficient number of
manholes should be provided in the subdrains to permit observation and flushing
of the subdrain system. Manhole covers should be capable of withstanding the
superimposed loads.
Special
conditions
19. It is recognized
that local conditions at some aerodrome sites may require additional surface
protection from erosion. In those circumstances, it is recommended that
additional pavement be provided. The pavement section and surface material to be
used should be governed by past satisfactory local experience. In approving low-cost
materials and procedures, maintenance time should be considered, particularly
for areas adjacent to critical- use “operational areas” or “taxiways.”
Table
A2-1. Distance at which blast velocity has been reduced to 56 km/h
Aircraft
type
|
Idle
thrust
(m)
|
Breakaway
thrust
(m)
|
Take-off
thrust
(m)
|
DC8
|
6
|
|
|
B727
|
29
|
49
|
130
|
B747
|
76
|
250
|
410
|
DC10
|
64
|
180
|
460
|
A320
|
17.5
|
48
|
380
|
B737-8
|
19
|
56
|
334
|
B777-300ER
|
43
|
99
|
689
|
B747-8
|
22
|
98
|
789
|
MD-11
|
65
|
160
|
564
|
A380
|
45
|
88
|
429
|
Table
A2-2. Blast velocity levels
|
Blast velocity at
15 m from the tail
|
Blast velocity at
30 m from the tail
|
Aircraft type
|
Idle
(km/h)
|
Breakaway
(km/h)
|
Take-off
(km/h)
|
Idle
(km/h)
|
Breakaway
(km/h)
|
Take-off
(km/h)
|
Commercial jets
|
|
|
|
|
|
|
|
|
|
|
|
|
|
DC8
|
29
|
122
|
210
|
14
|
96
|
161
|
B727
|
106
|
193
|
530
|
53
|
96
|
290
|
B747
|
74
|
164
|
320
|
67
|
143
|
260
|
DC10
|
116
|
260
|
610
|
85
|
177
|
420
|
A320
|
60
|
120
|
224*
|
45
|
79
|
215*
|
B737-8
|
56
|
80
|
241
|
N/A
|
56
|
241
|
B777-300ER
|
56
|
80
|
161
|
56
|
80
|
161
|
B747-8
|
56
|
80
|
322
|
N/A
|
80
|
241
|
MD-11
|
72
|
120
|
322
|
56
|
120
|
322
|
A380
|
78
|
132
|
262*
|
67
|
111
|
254*
|
(*) extrapolated values
|
|
|
|
|
|
|
Business jets
|
|
|
|
|
|
|
Lear-Commander
|
47
|
95
|
215
|
21
|
43
|
98
|
Falcon
|
72
|
137
|
305
|
43
|
64
|
146
|
Sabreliner
|
79
|
162
|
370
|
35
|
74
|
169
|
Gulfstream-II
|
145
|
297
|
675
|
80
|
141
|
320
|
Figure
A2-6. Aerodrome locations requiring blast fences
Figure
A2-7.Blast fences in apron areas
Figure
A2-8. Types of blast fences
APPENDIX 3
AEROPLANE CLASSIFICATION BY CODE NUMBER AND
LETTER
|
|
|
Aeroplane reference
field length
|
Wing span
|
Outer main gear
wheel span
|
Aircraft Make
|
Model
|
Code
|
(m)
|
(m)
|
(m)
|
DeHavilland Canada
|
DHC2
|
1A
|
381
|
14.6
|
3.3
|
|
DHC2T
|
1A
|
427
|
14.6
|
3.3
|
Britten Norman
|
BN2A
|
1A
|
353
|
14.9
|
4.0
|
Cessna
|
152
|
1A
|
408
|
10.0
|
-
|
|
172 S
|
1A
|
381
|
11.0
|
2.7
|
|
180
|
1A
|
367
|
10.9
|
-
|
|
182 S
|
1A
|
462
|
11.0
|
2.9
|
|
Stationair 6
|
1A
|
543
|
11.0
|
2.9
|
|
Turbo 6
|
1A
|
500
|
11.0
|
2.9
|
|
Stationair 7
|
1A
|
600
|
10.9
|
-
|
|
Turbo 7
|
1A
|
567
|
10.9
|
-
|
|
Skylane
|
1A
|
479
|
10.9
|
-
|
|
Turbo Skylane
|
1A
|
470
|
10.9
|
-
|
|
310
|
1A
|
518
|
11.3
|
-
|
|
310 Turbo
|
1A
|
507
|
11.3
|
-
|
|
Golden Eagle 421 C
|
1A
|
708
|
12.5
|
-
|
|
Titan 404
|
1A
|
721
|
14.1
|
-
|
Piper
|
PA28-161
|
1A
|
4941
|
10.7
|
3.2
|
|
PA28-181
|
1A
|
4901
|
10.8
|
3.2
|
|
PA28R-201
|
1A
|
4871
|
10.8
|
3.4
|
|
PA32R-301
|
1A
|
5391
|
11.0
|
3.5
|
|
PA32R-301T
|
1A
|
7561
|
11.0
|
3.5
|
|
PA34-220T
|
1A
|
5201
|
11.9
|
3.5
|
|
PA44-180
|
1A
|
6711
|
11.8
|
3.2
|
|
PA46-350P
|
1A
|
6371
|
13.1
|
3.9
|
Raytheon/Beechcraft
|
A24R
|
1A
|
603
|
10.0
|
3.9
|
|
A36
|
1A
|
670
|
10.2
|
2.9
|
|
76
|
1A
|
430
|
11.6
|
3.3
|
|
B55
|
1A
|
457
|
11.5
|
2.9
|
|
B60
|
1A
|
793
|
12.0
|
3.4
|
|
B100
|
1A
|
579
|
14.0
|
4.3
|
|
|
|
|
|
|
Cessna
|
525
|
1B
|
939
|
14.3
|
4.1
|
DeHavilland Canada
|
DHC3
|
1B
|
497
|
17.7
|
3.7
|
|
DHC6
|
1B
|
695
|
19.8
|
4.1
|
LET
|
L410 UPV
|
1B
|
740
|
19.5
|
4.0
|
Raytheon/Beechcraft
|
E18S
|
1B
|
753
|
15.0
|
3.9
|
|
B80
|
1B
|
427
|
15.3
|
4.3
|
|
C90
|
1B
|
488
|
15.3
|
4.3
|
|
200
|
1B
|
579
|
16.6
|
5.6
|
Short
|
SC7-3/SC7-3A
|
1B
|
616
|
19.8
|
4.6
|
|
|
|
|
|
|
DeHavilland Canada
|
DHC7
|
1C
|
689
|
28.4
|
7.8
|
|
|
|
|
|
|
Lear Jet
|
24F
|
2A
|
1 005
|
10.9
|
2.5
|
|
28/29
|
2A
|
912
|
13.4
|
2.5
|
|
|
|
|
|
|
Pilatus
|
PC-12
|
2B
|
810
|
16.3
|
4.5
|
|
PC-24
|
2B
|
830
|
17.0
|
3.3
|
LET
|
L410 UPV-E
|
2B
|
920
|
20.02
|
4.0
|
|
L410 UPV-E9
|
2B
|
952
|
20.02
|
4.0
|
|
L410 UPV-E20
|
2B
|
1 050
|
20.02
|
4.0
|
|
L420
|
2B
|
920
|
20.02
|
4.0
|
Shorts
|
SD3-30
|
2B
|
1 106
|
22.8
|
4.6
|
|
|
|
|
|
|
Dassault Aviation
|
Falcon 10
|
3A
|
1 615
|
13.1
|
3.0
|
Hawker Siddley
|
HS 125-400
|
3A
|
1 646
|
14.3
|
3.3
|
|
HS 125-600
|
3A
|
1 646
|
14.3
|
3.3
|
|
HS 125-700
|
3A
|
1 768
|
14.3
|
3.3
|
Lear Jet
|
24D
|
3A
|
1 200
|
10.9
|
2.5
|
|
35A/36A
|
3A
|
1 287/1 458
|
12.0
|
2.5
|
|
54
|
3A
|
1 217
|
13.4
|
2.5
|
|
55
|
3A
|
1 292
|
13.4
|
2.5
|
|
|
|
|
|
|
Bombardier Aero.
|
CRJ 100
|
3B
|
1 470
|
21.2
|
4.0
|
|
CRJ 100ER
|
3B
|
1 720
|
21.2
|
4.0
|
|
CRJ 200
|
3B
|
1 440
|
21.2
|
4.0
|
|
CRJ 200ER
|
3B
|
1 700
|
21.2
|
4.0
|
Dassault Aviation
|
Falcon 20
|
3B
|
1 463
|
16.3
|
3.7
|
|
Falcon 200
|
3B
|
1 700
|
16.3
|
3.5
|
|
F50/F50EX
|
3B
|
1 586
|
18.9
|
4.5
|
|
Falcon 900
|
3B
|
1 504
|
19.3
|
4.6
|
|
Falcon 900EX
|
3B
|
1 590
|
19.3
|
4.6
|
|
F2000
|
3B
|
1 658
|
19.3
|
5.0
|
Embraer
|
EMB-135 LR
|
3B
|
1 745
|
20.0
|
4.1
|
Fokker
|
F28-1000
|
3B
|
1 646
|
23.6
|
5.8
|
|
F28-2000
|
3B
|
1 646
|
23.6
|
5.8
|
I.A.I.
|
SPX
|
3B
|
1 644
|
16.6
|
-
|
|
Galaxy
|
3B
|
1 798
|
17.7
|
-
|
Gulfstream Aero.
|
G IV-SP
|
3B
|
1 661
|
23.7
|
4.8
|
Nord
|
262
|
3B
|
1 260
|
21.9
|
3.4
|
|
|
|
|
|
|
Antonov
|
AN24
|
3C
|
1 600
|
29.2
|
8.8
|
Airbus
|
A220-100
|
3C
|
1 423
|
35.1
|
6.7
|
|
A220-300
|
3C
|
1 797
|
35.1
|
6.7
|
|
A318-100
|
3C
|
1 779
|
34.1
|
8.9
|
|
A319-100 w/o sharklets
|
3C
|
1 799
|
34.1
|
8.9
|
|
A319-100 with sharklets
|
3C
|
1 799
|
35.8
|
8.9
|
|
A319neo
|
3C
|
1 735
|
35.8
|
8.9
|
|
A320-200 w/o sharklets3
|
3C
|
1 797
|
34.1
|
8.9
|
|
A320-200 with sharklets3
|
3C
|
1 797
|
35.8
|
8.9
|
|
A320neo
|
3C
|
1 775
|
35.8
|
8.9
|
Boeing
|
B717-200
|
3C
|
1 670
|
28.4
|
5.4
|
|
B737-600
|
3C
|
1 690
|
34.3
|
7.0
|
|
B737-700
|
3C
|
1 598
|
34.3
|
7.0
|
|
B737-8003
|
3C
|
1 799
|
34.3
|
7.0
|
|
B737-9003
|
3C
|
1 799
|
34.3
|
7.0
|
|
B737-73
|
3C
|
1 799
|
35.9
|
7.0
|
|
B737-83
|
3C
|
1 799
|
35.9
|
7.0
|
|
B737-93
|
3C
|
1 799
|
35.9
|
7.0
|
Convair
|
240
|
3C
|
1 301
|
28.0
|
8.4
|
|
440
|
3C
|
1 564
|
32.1
|
8.6
|
|
580
|
3C
|
1 341
|
32.1
|
8.6
|
|
600
|
3C
|
1 378
|
28.0
|
8.4
|
|
640
|
3C
|
1 570
|
32.1
|
8.6
|
Douglas
|
DC3
|
3C
|
1 204
|
28.8
|
5.8
|
|
DC4
|
3C
|
1 542
|
35.8
|
8.5
|
|
DC6A/6B
|
3C
|
1 375
|
35.8
|
8.5
|
|
DC9-20
|
3C
|
1 551
|
28.5
|
6.0
|
Embraer
|
EMB-120 ER
|
3C
|
1 481
|
19.8
|
6.6
|
|
EMB-170-100 STD
|
3C
|
1 431
|
26.0
|
6.3
|
|
EMB-170-100 LR
|
3C
|
1 524
|
26.0
|
6.3
|
|
EMB-170-200 LR/SU
|
3C
|
1 715
|
26.0
|
6.3
|
|
EMB-190-100 STD
|
3C
|
1 614
|
28.7
|
7.2
|
|
EMB-190-200 STD
|
3C
|
1 779
|
28.7
|
7.2
|
Fokker
|
F27-500
|
3C
|
1 670
|
29.0
|
7.9
|
|
F27-600
|
3C
|
1 670
|
29.0
|
7.9
|
|
F28-3000
|
3C
|
1 640
|
25.1
|
5.8
|
|
F28-4000
|
3C
|
1 640
|
25.1
|
5.8
|
|
F28-6000
|
3C
|
1 400
|
25.1
|
5.8
|
|
F50
|
3C
|
1 355
|
29.0
|
8.0
|
McDonnell Douglas
|
MD90
|
3C
|
1 798
|
32.9
|
6.2
|
SAAB
|
340A
|
3C
|
1 220
|
21.4
|
7.3
|
|
340B
|
3C
|
1 220
|
22.84
|
7.3
|
|
SAAB 2000
|
3C
|
1 340
|
24.8
|
8.9
|
|
|
|
|
|
|
Airbus
|
A300 B2
|
3D
|
1 676
|
44.8
|
10.9
|
Bae
|
ATP
|
3D
|
1 540
|
30.6
|
9.3
|
DeHavilland Canada
|
DHC5D
|
3D
|
1 471
|
29.3
|
10.2
|
Bombardier Aero.
|
CRJ100LR
|
4B
|
1 880
|
21.2
|
4.0
|
|
CRJ200LR
|
4B
|
1 850
|
21.2
|
4.0
|
Dassault Aviation
|
Falcon 20-5 (Retrofit)
|
4B
|
1 859
|
16.3
|
3.7
|
Embraer
|
EMB-145 LR
|
4B
|
2 269
|
20.0
|
4.1
|
|
|
|
|
|
|
Airbus
|
A320-200 w/o sharklets
|
4C
|
2 111
|
34.1
|
8.9
|
|
A320-200 with sharklets
|
4C
|
2 108
|
35.8
|
8.9
|
|
A321-200 w/o sharklets
|
4C
|
2 513
|
34.1
|
8.9
|
|
A321-200 with sharklets
|
4C
|
2 513
|
35.8
|
8.9
|
|
A321neo
|
4C
|
2 366
|
35.8
|
8.9
|
|
|
|
|
|
|
BAC
|
1-11-200
|
4C
|
1 884
|
27.0
|
5.2
|
|
1-11-300
|
4C
|
2 484
|
27.0
|
5.2
|
|
1-11-400
|
4C
|
2 420
|
27.0
|
5.2
|
|
1-11-475
|
4C
|
2 286
|
28.5
|
5.4
|
|
1-11-500
|
4C
|
2 408
|
28.5
|
5.2
|
Boeing
|
B727-100
|
4C
|
2 502
|
32.9
|
6.9
|
|
B727-200
|
4C
|
3 176
|
32.9
|
6.9
|
|
B737-100
|
4C
|
2 499
|
28.4
|
6.4
|
|
B737-200
|
4C
|
2 295
|
28.4
|
6.4
|
|
B737-300
|
4C
|
2 160
|
28.9
|
6.4
|
|
B737-400
|
4C
|
2 550
|
28.9
|
6.4
|
|
B737-500
|
4C
|
2 470
|
28.9
|
6.4
|
|
B737-800
|
4C
|
2 090
|
34.3
|
7.0
|
|
B737-900
|
4C
|
2 240
|
34.3
|
7.0
|
|
B737-7
|
4C
|
2 375
|
35.9
|
7.0
|
|
B737-8
|
4C
|
2 600
|
35.9
|
7.0
|
|
B737-9
|
4C
|
3 100
|
35.9
|
7.0
|
Embraer
|
EMB-170-200 STD
|
4C
|
2 221
|
26.0
|
6.3
|
|
EMB-170-200 LR
|
4C
|
2 221
|
28.7
|
6.3
|
|
EMB-170-200 AR
|
4C
|
2 221
|
26.0
|
6.3
|
|
EMB-190-100 LR
|
4C
|
2 064
|
28.7
|
7.2
|
|
EMB-190-100 IGW
|
4C
|
2 220
|
28.7
|
7.2
|
|
EMB-190-200 LR
|
4C
|
2 179
|
28.7
|
7.2
|
|
EMB-190-200 AR
|
4C
|
2 383
|
28.7
|
7.2
|
Fokker
|
F100
|
4C
|
1 840
|
28.1
|
6.0
|
Gulfstream Aero
|
G V
|
4C
|
1 863
|
28.5
|
5.1
|
Douglas
|
DC9-10
|
4C
|
1 975
|
27.2
|
5.9
|
|
DC9-15
|
4C
|
1 990
|
27.3
|
6.0
|
|
DC9-20
|
4C
|
1 560
|
28.4
|
6.0
|
|
DC9-30
|
4C
|
2 134
|
28.5
|
5.9
|
|
DC9-40
|
4C
|
2 091
|
28.5
|
5.9
|
|
DC9-50
|
4C
|
2 451
|
28.5
|
5.9
|
McDonnell Douglas
|
MD81
|
4C
|
2 290
|
32.9
|
6.2
|
|
MD82
|
4C
|
2 280
|
32.9
|
6.2
|
|
MD83
|
4C
|
2 470
|
32.9
|
6.2
|
|
MD87
|
4C
|
2 260
|
32.9
|
6.2
|
|
MD88
|
4C
|
2 470
|
32.9
|
6.2
|
Airbus
|
A300B4-200
|
4D
|
2 727
|
44.8
|
11.1
|
|
A300-600R
|
4D
|
2 279
|
44.8
|
11.1
|
|
A310-300
|
4D
|
2 350
|
43.9
|
11.0
|
Boeing
|
B707-300
|
4D
|
3 088
|
44.4
|
7.9
|
|
B707-400
|
4D
|
3 277
|
44.4
|
7.9
|
|
B720
|
4D
|
1 981
|
39.9
|
7.5
|
|
B757-200
|
4D
|
1 980
|
38.1
|
8.6
|
|
B757-300
|
4D
|
2 400
|
38.1
|
8.6
|
|
B767-200
|
4D
|
1 981
|
47.6
|
10.8
|
|
B767-300ER
|
4D
|
2 540
|
47.6
|
10.9
|
|
B767-400ER
|
4D
|
3 130
|
51.9
|
10.8
|
Canadair
|
CL44D-4
|
4D
|
2 240
|
43.4
|
10.5
|
Ilyushin
|
18V
|
4D
|
1 980
|
37.4
|
9.9
|
|
62M
|
4D
|
3 280
|
43.2
|
8.0
|
Lockheed
|
L100-20
|
4D
|
1 829
|
40.8
|
4.9
|
|
L100-30
|
4D
|
1 829
|
40.4
|
4.9
|
|
L188
|
4D
|
2 066
|
30.2
|
10.5
|
|
L1011-1
|
4D
|
2 426
|
47.3
|
12.8
|
|
L1011-100/200
|
4D
|
2 469
|
47.3
|
12.8
|
|
L1011-500
|
4D
|
2 844
|
47.3
|
12.8
|
Douglas
|
DC8-61
|
4D
|
3 048
|
43.4
|
7.5
|
|
DC8-62
|
4D
|
3 100
|
45.2
|
7.6
|
|
DC8-63
|
4D
|
3 179
|
45.2
|
7.6
|
|
DC8-71
|
4D
|
2 770
|
43.4
|
7.5
|
|
DC8-72
|
4D
|
2 980
|
45.2
|
7.6
|
|
DC8-73
|
4D
|
3 050
|
45.2
|
7.6
|
McDonnell Douglas
|
DC10-10
|
4D
|
3 200
|
47.4
|
12.6
|
|
DC10-30
|
4D
|
3 170
|
50.4
|
12.6
|
|
DC10-40
|
4D
|
3 124
|
50.4
|
12.6
|
Tupolev
|
TU134A
|
4D
|
2 400
|
29.0
|
10.3
|
|
TU154
|
4D
|
2 160
|
37.6
|
12.4
|
|
|
|
|
|
|
Airbus
|
A330-200
|
4E
|
2 820
|
60.3
|
12.6
|
|
A330-300
|
4E
|
2 776
|
60.3
|
12.6
|
|
A340-200
|
4E
|
2 891
|
60.3
|
12.6
|
|
A340-300
|
4E
|
2 989
|
60.3
|
12.6
|
|
A340-500
|
4E
|
3 023
|
63.4
|
12.6
|
|
A340-600
|
4E
|
3 189
|
63.4
|
12.6
|
|
A350-900
|
4E
|
2 631
|
64.7
|
12.9
|
|
A350-1000
|
4E
|
2 754
|
64.7
|
12.8
|
Boeing
|
B747-100
|
4E
|
3 060
|
59.6
|
12.4
|
|
B747-200
|
4E
|
3 150
|
59.6
|
12.4
|
|
B747-300
|
4E
|
3 292
|
59.6
|
12.4
|
|
B747-400
|
4E
|
2 890
|
64.95
|
12.6
|
|
B747-SR
|
4E
|
1 860
|
59.6
|
12.4
|
|
B747-SP
|
4E
|
2 710
|
59.6
|
12.4
|
|
B777-200
|
4E
|
2 390
|
61.0
|
12.9
|
|
B777-200ER
|
4E
|
3 110
|
61.0
|
12.9
|
|
B777-300
|
4E
|
3 140
|
60.9
|
12.9
|
|
B777-300ER
|
4E
|
3 120
|
64.8
|
12.9
|
|
B787-8
|
4E
|
2 600
|
60.1
|
9.8
|
|
B787-9
|
4E
|
2 800
|
60.1
|
9.8
|
|
B787-10
|
4E
|
2 800
|
60.1
|
9.8
|
McDonnell Douglas
|
MD11
|
4E
|
3 130
|
52.05
|
12.6
|
Airbus
|
A380
|
4F
|
2 865
|
79.8
|
14.3
|
Boeing
|
B747-8
|
4F
|
2 956
|
68.4
|
12.7
|
|
B777-9
|
4F
|
2 9006
|
71.8
|
12.8
|
1. Over a 15 m obstacle.
2. With wing tip tanks installed.
3. Alternate maximum take-off weight consult
manufacture airport planning manual or airline operator.
4. With extended wing tips.
5. Winglets.
6. Preliminary data.
APPENDIX 4
TAXIWAY DEVIATION STUDIES
Introduction
Note: There have been
several studies to measure aircraft deviations from taxiway centre lines. This
appendix contains examples of studies conducted in London and Amsterdam. The results
are specific or particular to each airport, pavement surfaces and weather
conditions. While these studies may be of guidance to those intending to carry
out similar studies, it may not be appropriate to use the results directly
where any or some of the local factors are different from those used in these studies.
Safety of operations must be the overriding concern whenever studies aimed at
operating with separation distances less than the minimum safety clearances
specified in Table 3-1 of Annex 14, Volume I are contemplated.
London/Heathrow
study
1. A taxiway
deviation study was carried out by British Airports Public Ltd. at London
Heathrow Airport. Over 77 000 aircraft taxiing movements in all weather
conditions were recorded. The purpose of the study was to show that pilots do
not deviate significantly from the centre line when taxiing. The analysis of the
data had two objectives. The primary objective was to estimate the probability
of two Boeing 747-400 aircraft colliding wing tips when passing each other on
parallel taxiways. The secondary objective was to estimate the expected number
of years that would elapse before this collision occurred. The study also
attempted to assess the adequacy of the separation distances between parallel
taxiway runways and between taxiways and objects, as recommended in Annex 14,
Volume I, Table 3-1.
Straight
sections of taxiways
2. Based on some 2
000 observations of B747 deviations on the straight sections of taxiways, the
study concluded that the probability of two B747-400 aircraft colliding when
passing each other on parallel taxiways is around 10-8, i.e. 1 in
100 million. This assumes that the taxiway centre lines are 76.5 m apart and
that the aircraft have a wing span of 65 m. Upon analysing the data in the
large data base which had been established, there was ample evidence to
indicate that taxiing aircraft do not deviate from taxiway centre lines to any
great degree. The data also provided an estimate of the number of occasions per
year that two standard B747s pass each other on Heathrow’s parallel taxiways.
This would be about 80 occasions per year out of around 34 000 B747 air
transport movements. This low figure occurredbecause, in the majority of cases,
theaircraft would be moving in the same direction through the taxiway system. Departing
aircraft use one runway and arriving aircraft use another; their paths rarely
overlap.
Figure A4-1 shows the
distribution of deviations upon which the analysis is based.
Curved
sections of taxiways
3. It was considered
that the probability of collision on curved sections on taxiways is of the same
order of magnitude as in straight sections, i.e. 10-8. There were not
enough observations of B747 deviations on the curved sections of taxiway to repeat
the analysis detailed for straight sections. Data were collected at two
locations. Data from the inner curve proved not to be useful because there was
a large paved area to the inside of it which pilots tended to cut across. The
number of observations on the outer curve was low because several months of maintenance
work had closed that part of the taxiway. Figure A4-2 shows the distribution of
the 185 B747 deviations observed on the outer curve. The negative numbers are
deviations from the centre line towards the inside of the curve. This is in a
different form to Figure A4-1 which shows only absolute deviations. Figure A4-2
shows that almost all aircraft main wheels cut across the corner. For a
collision to occur at a curved part of the parallel taxiway, the outer aircraft
must deviate to the inside and the inner aircraft must deviate to the outside. Figure
A4-2 shows that the latter is very unlikely to happen. The overall distribution
suggests that the collision probability would be similar to that of straight
sections, i.e. 10-8 Curved sections of taxiways were regarded as
less of a problem than straight sections of taxiways since there will always be
fewer curved elements in a given taxiway layout. Thus, the chance that two
aircraft pass on a curved section is much less than on a straight section.
Speed
effect
4. The analysis
showed that an aircraft’s speed does not affect its lateral deviation.
Bad
weather effect
5. No link could be
established between bad weather and large taxiway deviations. During the data
collection period, most weather conditions were encountered including snow
fall, heavy rain, strong winds and visibility reduced to 1 000 m.
Statistics
for all aircraft
6. Tables A4-1 and
A4-2 show summary statistics for all aircraft on the straight and the outer
curved sections of taxiways, respectively.
Amsterdam
Schiphol study
7. A taxiway centre line
deviation test was conducted at Amsterdam’s Schiphol Airport from October 1988
to September 1991. Over 9 000 ICAO Category E aircraft (mostly B747) taxiing
movements were recorded over the three- year span. Using infra-red beams, data were
collected for a straight and a curved section of the taxiway. The taxiway width
was 22.9 m. The curved section had a centre line radius of 55 m and a turn of
120 degrees. Centre line lighting was provided on both sections of taxiway.
8. The data were used
by the Boeing Company to accomplish a statistical analysis of aircraft landing gear
deviations. The purpose of the study was to estimate the extreme probabilities
of gear deviations (those well outside the range of observed deviations), as
well as to obtain estimates of the probability of wing tip contact between two
aircraft on parallel taxiways.
9. A summary of
statistics for the taxiway data is provided in Table A4-3. The data from the curved
section indicates that pilots of large aircraft use a judgmental oversteer
technique to insure that the main landing gear remains on the pavement.
Deviation
probability estimates
10. The fact that
data do not exist for gear deviations greater than 3.54 m on straight taxiways
necessitates extrapolation for probabilities for greater deviations.
Wing
tip contact probability
11. Using the extrapolated
probabilities of extreme main gear deviations, the probabilities of wing
tip-to-wing tip contact between two aircraft on parallel taxiways were
calculated. These probabilities depend on the probability distribution of the
sum of the two taxiway deviations, noting that two simultaneous deviations on parallel
taxiways are statistically independent.
12. Table A4-4
summarizes estimates of required taxiway separations and estimated 90 per cent
upper bounds for various wingspan probabilities.
Estimates
of required taxiway separations
13. As an example,
the mean estimate of taxiway separation required for a probability of a 109
wing tip contact between two aircraft with 73.2 m wingspans is 80.5 m.
Conditions
affecting deviation
14. Some conditions
that were recorded with the deviation were the year, month, day, time, taxi
speed and direction. The variability of deviations was not affected by these
factors. For example, the standard deviation on the straight section is 68.8
cm. The standard deviation is 67.1 cm after removing any systematic deviation
due to taxi direction, season and time of day. Thus, the practical significance
(in contrast to the statistical significance) of these effects may be minimal.
Figure
A4-1. B747 main wheel deviations for straight sections of taxiway
Figure
A4-2. B747 main wheel deviations for curved sections of taxiway
Table
A4-1. Summary statistics (straight sections of taxiway)
|
Main wheel deviation
(m)
|
Nose wheel deviation
(m)
|
Speed (kt)
|
|
Aircraft
|
Mean
|
95%
|
Max
|
Mean
|
95%
|
Max
|
Mean
|
95%
|
Max
|
Observations
|
A310
|
0.60
|
1.42
|
9.0
|
0.56
|
1.37
|
9.1
|
18.8
|
25
|
35
|
1 213
|
B727
|
0.65
|
1.85
|
8.1
|
0.56
|
1.36
|
9.0
|
18.9
|
27
|
49
|
1 997
|
B737
|
0.81
|
1.90
|
9.1
|
0.68
|
1.62
|
8.5
|
17.2
|
25
|
35
|
9 035
|
B747
|
0.59
|
1.90
|
4.1
|
0.47
|
1.21
|
7.8
|
17.3
|
25
|
34
|
1 988
|
B757
|
0.72
|
1.74
|
7.9
|
0.63
|
1.43
|
6.1
|
16.1
|
24
|
35
|
6 089
|
|
|
|
|
|
|
|
|
|
|
|
BAC1-11
|
0.65
|
1.53
|
9.5
|
0.63
|
1.49
|
8.2
|
15.8
|
23
|
33
|
3 749
|
DC9S
|
0.68
|
1.62
|
9.5
|
0.63
|
1.50
|
8.7
|
17.2
|
25
|
39
|
2 941
|
DC9
|
0.59
|
1.44
|
8.4
|
0.57
|
1.42
|
8.2
|
16.2
|
24
|
33
|
2 885
|
F27
|
0.95
|
2.39
|
9.6
|
0.62
|
1.47
|
9.6
|
17.9
|
26
|
32
|
1 075
|
F28
|
1.26
|
5.73
|
10.0
|
1.00
|
4.63
|
9.2
|
17.2
|
24
|
33
|
745
|
|
|
|
|
|
|
|
|
|
|
|
S360
|
0.80
|
2.00
|
7.4
|
0.63
|
1.43
|
9.2
|
17.1
|
23
|
27
|
1 528
|
L1011
|
0.50
|
1.22
|
8.9
|
0.46
|
1.13
|
5.2
|
17.1
|
25
|
31
|
722
|
Table
A4-2. Summary statistics (outer taxiway curve)
|
Main wheel deviation
(m)
|
Nose wheel deviation
(m)
|
Speed (kt)
|
|
Aircraft
|
Mean
|
Min
|
5%
|
95%
|
Max
|
Mean
|
Min
|
5%
|
95%
|
Max
|
Mean
|
95%
|
Max
|
Observations
|
A310
|
-2.2
|
-6.4
|
-3.9
|
-0.5
|
+0.6
|
+0.54
|
-6.0
|
-1.3
|
+2.4
|
+4.6
|
16.0
|
21
|
27
|
848
|
B727
|
-1.92
|
-7.5
|
-3.7
|
+0.2
|
+2.5
|
+0.37
|
-5.2
|
-1.5
|
+2.2
|
+6.1
|
17.0
|
23
|
33
|
1 044
|
B737
|
-0.75
|
-5.0
|
-2.5
|
+0.9
|
+5.8
|
+0.32
|
-5.4
|
-1.4
|
+2.1
|
+5.4
|
16.6
|
22
|
30
|
3 152
|
B747
|
-3.31
|
-7.6
|
-5.7
|
-0.5
|
+0.1
|
-0.04
|
-4.1
|
-2.4
|
+2.6
|
+5.3
|
15.3
|
22
|
25
|
185
|
B757
|
-1.50
|
-7.7
|
-3.2
|
0.0
|
+2.5
|
+0.08
|
-3.7
|
-1.5
|
+2.0
|
+4.7
|
16.3
|
21
|
27
|
2 425
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
BAC1-11
|
-1.10
|
-9.7
|
-3.0
|
+0.7
|
+4.2
|
+0.47
|
-5.8
|
-1.4
|
+2.4
|
+6.1
|
16.4
|
22
|
27
|
962
|
DC9S
|
-1.09
|
-9.0
|
-3.2
|
+1.0
|
+3.6
|
-0.29
|
-8.3
|
-2.6
|
+1.9
|
+5.7
|
16.2
|
22
|
29
|
1 510
|
DC9
|
-1.11
|
-7.2
|
-3.0
|
-0.8
|
+2.0
|
+0.28
|
-3.0
|
-1.7
|
+2.3
|
+6.7
|
15.9
|
22
|
26
|
557
|
F27
|
-1.69
|
-7.4
|
-4.0
|
+0.4
|
+8.0
|
+0.39
|
-4.2
|
-1.4
|
+2.4
|
+9.2
|
17.1
|
23
|
27
|
465
|
F28
|
-1.33
|
-8.2
|
-3.8
|
+0.7
|
+9.2
|
+0.52
|
-8.9
|
-1.4
|
+2.5
|
+6.0
|
17.2
|
22
|
26
|
467
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
S360
|
-0.71
|
-9.6
|
-2.8
|
+1.1
|
+8.7
|
+0.47
|
-3.7
|
-1.3
|
+2.4
|
+4.2
|
17.0
|
22
|
25
|
534
|
L1011
|
-2.8
|
-5.9
|
-4.5
|
-0.8
|
+1.4
|
+0.18
|
-4.4
|
-2.2
|
+2.3
|
+3.4
|
14.5
|
20
|
26
|
255
|
Table
A4-3. Summary of taxiway data
|
ICAO
Code
E Aircraft
|
B747
(All models)
|
Schiphol
Report Code E Aircraft
|
Nose
|
Main
|
Nose
|
Main
|
Nose
|
Main
|
Straight
section
|
Sample
size
|
7
958
|
7
958
|
7
855
|
7
855
|
8
191
|
8
191
|
Mean
(cm)
|
-14.8
|
-12.5
|
-15.2
|
-13.2
|
-8.0
|
-26.0
|
Std.
dev. (cm)
|
68.5
|
76.4
|
67.4
|
68.8
|
68.0
|
70.0
|
Curved
section
|
Sample
size
|
1
382
|
1
382
|
1
351
|
1
351
|
1
380
|
1
380
|
Mean
(cm)[3]
|
393.5
|
-202.2
|
400.3
|
-199.8
|
389
|
-199
|
Std.
dev. (cm)
|
244.1
|
236.8
|
237.6
|
236.0
|
227
|
216
|
Table
A4-4. Estimates of taxiway separations and 90 per cent upper bounds
|
Estimates
|
|
90% bounds
|
Wingspan
|
10e-6
|
10e-7
|
10e-8
|
10e-9
|
|
10e-6
|
10e-7
|
10e-8
|
10e-9
|
67
|
72.8
|
73.4
|
73.9
|
74.4
|
|
73.3
|
73.9
|
74.6
|
75.2
|
70
|
75.8
|
76.4
|
76.9
|
77.4
|
|
76.4
|
76.7
|
77.6
|
78.2
|
73
|
78.9
|
79.5
|
80.0
|
80.5
|
|
79.4
|
80.0
|
80.7
|
81.3
|
76
|
81.9
|
82.5
|
83.0
|
83.5
|
|
82.4
|
83.1
|
83.7
|
84.3
|
79
|
85.0
|
85.6
|
86.1
|
86.6
|
|
85.5
|
86.1
|
86.7
|
87.4
|
82
|
88.0
|
88.6
|
89.1
|
89.6
|
|
88.5
|
89.2
|
89.8
|
90.4
|
85
|
91.1
|
91.7
|
92.2
|
92.7
|
|
91.6
|
92.2
|
92.8
|
93.5
|
APPENDIX 5
DESIGN, LOCATION AND NUMBER OF RAPID EXIT
TAXIWAYS
5.1 Process of determination of the optimal
location of the turn-off point
5.2
Example for the use of the method described in Chapter 1, 1.3
The following example
is provided to illustrate the use of the method described in Chapter 1, 1.3.
The calculations are based on the following assumptions:
• Aerodrome Reference
Code number 4
• In order to enhance runway
capacity under specified conditions, a new exit should be located between 1 800
m and 2 500 m from threshold on a non- instrument runway with a length of 2 500
m. In the touch down area the runway slope is -0.75 per cent.
• The exit should be
commissioned by 2020.
• The runway should provide
its full capacity in strong headwind conditions (headwind > 15 kt). In this
situation it is the only runway available for landing as well as for take-off
at this airport, and it has to serve all types of aircraft.
• In light wind
conditions the runway is used exclusively for landing by commuter aircraft; for
take-off, however, it is used by all types of aircraft, subject to the
performance capabilities of the aircraft.
5.3
Example for the design of a non-standard rapid exit taxiway
Chapter 1, 1.3.19 and
Figure 1-6 specify that the construction of a standard RET would normally
require a distance between the centre lines of the runway and a parallel
taxiway of at least
(where dR is
the additional distance required for turns onto the taxiway centre line).
An alternate method
for the construction of a parallel taxiway spaced at 120 m, which would
accommodate a higher turn-off speed, as compared to a right-angled exit
taxiway, is described below and shown in Figure A5-3.
The exit was designed
as follows:
• Centre line: The first part of the
turn-off curve approximates the shape of a spiral, with an initial turnoff
radius of 160 m changing to 100 m in the second part. When an angle of 60°
between the taxiway centre line and the runway axis is reached, the radius changes
to 40 m. The third part of the turn shows a constant radius of 40 m until the
180° turn is completed.
• Turn-off speed: According to Chapter
1, Table 1-8, the turn-off speed is 24 kt for a radius of 160 m. The turn-off
speed for a 40 m radius is 13 kt. The distance required for the aircraft to
decelerate from 24 to 13 kt is approximately 140 m. This leads to a
deceleration rate of a = 0.4 m/s2 along the turn-off curve, which is
a safe value for all types of aircraft.
• Inside fillet curve: The inside fillet
curve was designed to allow access to all types of aircraft using this airport.
The critical aircraft is the B777-300 which at the present time has the longest
datum length.
• Outer edge: In order to allow
intersection take-offs from this exit, the outer edge is designed with a simple
right angle. The distance from the centre line to the outer edge is 20 m at the
closest point, providing adequate safety for all turning manoeuvres.
5.4 Calculation of the turn-off curve
The coordinates of
the basic points of the turn-off curve were determined as shown in Figure A5-4
and in the following calculations (all values in metres).
With
R1 = 160 m
R2 = 100 m
R3 = 40 m
the calculations are
valid for 112 m < s < 127 m where S is the distance from
centre line RWY to centre line TWY.
Table
A5-1. Anticipated fleetmix, 2020-2030
Aircraft
|
Share:
|
B747
|
1.2%
|
B777
|
1.2%
|
A340
|
6.7%
|
A3xx
|
0.2%
|
B757
|
1.4%
|
B767
|
1.7%
|
B737*
|
22.3%
|
A330
|
6.4%
|
A320*
|
35.9%
|
RJ*
|
18.1%
|
Misc.
|
4.9%
|
Total
|
100.0%
|
Table
A5-2. Optimal turn-off points and segments
Turn-off point [m]:
|
Turn-off segment
[m]:
|
A/C served at Vwind
[kt]:
|
Sum of share [%]:
|
|
|
B737
|
A320
|
RJ
|
|
1 530
|
1 430 - 1 730
|
25
|
|
20, 25
|
59
|
1 620
|
1 520 - 1 820
|
20, 25
|
25
|
15, 20, 25
|
135
|
1 660
|
1 560 - 1 860
|
20, 25
|
25
|
15, 20
|
117
|
1 760
|
1 660 - 1 960
|
15, 20, 25
|
20, 25
|
15
|
157
|
1 800
|
1 700 - 2 000
|
15, 20
|
15, 20, 25
|
15
|
170
|
1 870
|
1 770 - 2 070
|
15
|
15, 20
|
0, 15
|
130
|
1 980
|
1 880 - 2 180
|
|
15
|
0
|
54
|
2 040
|
1 940 - 2 240
|
0
|
15
|
0
|
76
|
2 210
|
2 110 - 2 410
|
0
|
0
|
|
58
|
2 330
|
2 230 - 2 530
|
|
0
|
|
36
|
Figure
A5-1. Optimal turn-off segment - A320
Figure
A5-2. Optimal turn-off point
Figure
A5-3. An alternative exit taxiway design
Figure
A5-4. Calculation of the turn-off curve