BỘ GIAO
THÔNG VẬN TẢI
CỤC HÀNG KHÔNG VIỆT NAM
-------
|
CỘNG HÒA
XÃ HỘI CHỦ NGHĨA VIỆT NAM
Độc lập - Tự do - Hạnh phúc
---------------
|
Số:
1045/QĐ-CHK
|
Hà Nội,
ngày 10 tháng 5 năm 2024
|
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
|
Subject(s)/ Amendment
|
Source
|
Effective date
|
Note
|
10th May 2024
|
First Edition
|
ICAO Doc 9157 - Part 2 (2020)
|
10th May 2024
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
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
|
D
|
E
|
F
|
Minimum
width of
|
|
|
|
|
|
|
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