IV-1
Part IV
COMMUNICATIONS, NAVIGATION
AND SURVEILLANCE (CNS)
INTRODUCTION
1. This part of the Asia and Pacific (ASIA/PAC)
Basic Air Navigation Plan contains elements of the existing
planning system and introduces the basic planning
principles, operational requirements and planning criteria
related to communications, navigation and surveillance
(CNS) as developed for the ASIA/PAC regions.
2. As a complement to the Statement of Basic
Operational Requirements and Planning Criteria (BORPC)
set out in Part I, Part IV constitutes the stable guidance
material considered to be the minimum necessary for
effective planning of CNS facilities and services in the
ASIA/PAC regions. A detailed description/list of the
facilities and/or services to be provided by States in order to
fulfil the requirements of the plan is contained in the
ASIA/PAC Facilities and Services Implementation
Document (FASID). During the transition and pending full
implemen-tation of the future communications, navigation
and surveillance/air traffic management (CNS/ATM)
system, it is expected that the existing requirements will
gradually be replaced by new CNS/ATM system-related
requirements. Further, it is expected that some elements of
CNS/ATM system will be subject to amendment, as
necessary, on the basis of experience gained in their
implementation.
3. The Standards, Recommended Practices and
Procedures to be applied are contained in:
a) Annex 10 — Aeronautical Telecommunications,
Volumes I, II, III, IV and V;
b) Annex 11 — Air Traffic Services; and
c) Regional Supplementary Procedures (Doc 7030).
4. Background information of importance in the
understanding and effective application of this part of the
plan is contained in the Report of the Third Asia/Pacific
Regional Air Navigation Meeting (Doc 9614, ASIA/PAC/3
(1993)) on Agenda Items 10, 11 and 12.
5. The elements of the material referred to above are
presented in the following paragraphs with appropriate
cross-references to recommendations and/or conclusions of
ASIA/PAC/3 and regional planning groups.
COMMUNICATIONS
General
6. The plan and details of the operational
requirements for communications are contained in Tables
CNS 1A, CNS 1B, CNS 1C, CNS 1D, CNS 1E, CNS 2,
CNS 3, CNS 4A and CNS 4B, and associated charts of Part
IV of the FASID.
Ground-ground communications
Aeronautical fixed service (AFS)
7. The aeronautical fixed service comprises:
a) the aeronautical fixed telecommunication network
(AFTN);
b) data communications subnetworks and associated
systems supporting the ground-ground applications of
the aeronautical telecommunication network (ATN),
IV-2 ASIA/PAC BASIC ANP
namely the ATS message handling services (ATS
MHS) and ATS inter-facility data communications
(AIDC);
c) ATS direct speech circuits; and
d) meteorological operation circuits, networks and
broadcast systems.
Aeronautical fixed telecommunication
network (AFTN)
8. States should ensure that telecommunication
agencies engaged in providing aeronautical circuits be
impressed of the need for:
a) high reliability terrestrial links connecting aeronautical
facilities and common carrier terminals inclusive of
priority restoration of service commensurate with the
requirements of a safety service; and
b) rapid restoration of circuits in the event of breakdown.
[ASIA/PAC/3, Conc. 10/1]
9. States operating AFTN circuits which do not
function satisfactorily 97 per cent of the time during which
the circuit is scheduled to be in operation should exchange
monthly circuit performance charts on the form provided in
Attachment A. Where a circuit consistently achieves
97 per cent reliability, the exchange of performance charts
may cease. The circuit performance charts should be
exchanged directly between the correspondent stations,
with copies to the administrations concerned and to the
ICAO Regional Office. States should also identify the
causes for inadequate circuit performance and take
necessary remedial measures.
[ASIA/PAC/3, Conc. 10/2]
10. States responsible for the operation of AFTN
circuits which are not adequately meeting transit time
requirements should record transit time statistics on the
twenty-third day of each third month (January, April, July
and October) of each year, in accordance with the existing
practices, for the AFTN circuits and terminals under their
jurisdiction which do not meet the specified transit time
criteria. The data recorded should be exchanged directly
between the correspondent stations, with copies to
administrations concerned and to the ICAO Regional
Office.
[ASIA/PAC/3, Conc.10/3]
11. States operating AFTN circuits should:
a) record AFTN statistics on the form contained in
Attachment B, from 23 to 25 April and October each
year;
b) exchange the circuit loading data for each circuit with
each correspondent station and provide a copy to the
ICAO Regional Office; and
c) evaluate circuit loading and take appropriate remedial
action when occupancy level exceeds permissible levels
specified in the Manual on the Planning and
Engineering of the Aeronautical Fixed
Telecommunications Network (Doc 8259).
[ASIA/PAC/3, Conc. 10/4]
12. States concerned should take positive measures to
ensure system reliability and provide adequate management
and supervision of facilities to eliminate system failure, and
to ensure data integrity and timely delivery of messages.
[ASIA/PAC/3, Conc. 10/5]
13. The AFTN entry/exit points:
a) between ASIA/PAC and AFI should be Brisbane and
Mumbai;
b) between ASIA/PAC and EUR should be Bangkok,
Singapore and Tokyo;
c) between ASIA/PAC and MID should be Karachi,
Mumbai and Singapore;
d) between ASIA/PAC and NAM should be Brisbane,
Nadi and Tokyo; and
e) between ASIA/PAC and CAR/SAM should be
Brisbane.
[APANPIRG/11, Conc. 11/6]
Technical aspects of AFTN rationalization.
14. The main trunk circuits interconnecting main
AFTN communication centres should be provided by
landline teletypewriter (LTT) facilities, operate at a
modulation rate commensurate with operational
requirements, and employ International Alphabet Number 5
(IA-5) and character-oriented data link control procedures
— system category B, or bit-oriented data link control
procedures as defined in Annex 10, Volume III, Part I,
Chapter 8.
15. Also, the tributary circuits interconnecting
CNS IV-3
tributary AFTN communication centres with main AFTN
communi-cation centres, with other tributary AFTN
communication centres, or with AFTN stations should be
provided with LTT facilities where available and feasible,
preferably operate at a modulation rate commensurate with
operational requirements, and employ IA-5 code and
procedures and an appropriately controlled circuit protocol.
[ASIA/PAC AFS RPG/3, Rec. 3/1]
16. To support data communication requirements and
to provide needed data integrity and minimal transit time,
the CCITT X.25 protocol should be used between AFTN
COM centres and main and tributary COM centres in the
ASIA/PAC regions.
[APANPIRG/4, Conc. 4/27 and APANPIRG/7, Conc. 7/14]
17. States should consider implementing digital
communication networks or circuits in a coordinated
manner in order to meet current and future AFS
communication requirements for data/voice
communications and to facilitate the introduction of ATN.
[APANPIRG/11, Conc. 11/14]
ATN infrastructure transition
and implementation
18. The ATN transition plan outlines the
requirements to increase bandwidth and upgrade protocols
for those trunk circuits that will support main data flow of
traffic in the ASIA/PAC regions. The plan also provides
target dates for implementation of boundary intermediate
systems (BIS) and backbone BIS in the ASIA/PAC regions.
[APANPIRG/12, Conc. 12/14]
19. ATN development should be introduced in an
evolutionary and cost-effective manner based on available
ICAO SARPs and regional ATN technical and planning
documents. The ATN infrastructure transition is expected
to be implemented in three phases as follows:
a) Phase 1. Upgrade of existing AFTN circuits where
necessary to support the introduction of the ATN
backbone BIS;
b) Phase 2. Implementation of the ATN regional backbone
BIS; and
c) Phase 3. Implementation of supporting ATN BIS.
20. States should consider establishment of gateways,
where required, to allow inter-operation between AFTN
and ATS MHS.
ATS direct speech circuits
ATS direct speech communications.
21. States concerned should assign a high priority to
the establishment, in accordance with Annex 11, 3.6.1.1, of
efficient direct-speech communications between ATS units
serving adjacent areas in order to permit proper use of
air-ground frequencies and further implementation of the
air traffic control (ATC) service.
[ASIA/PAC/3, Conc. 5/21]
22. Voice switching centres should be provided at the
following locations:
1) Auckland 2) Bangkok
3) Beijing 4) Mumbai
5) Calcutta 6) Guangzhou
7) Jakarta 8) Karachi
9) Lahore 10) Kuala Lumpur
11) Chennai 12) Nadi
13) Tokyo 14) Brisbane
[ASIA/PAC/3, Rec. 10/15]
23. Dissemination of World Area Forecast System
(WAFS) products in the ASIA/PAC regions will be
accomplished by satellite broadcast.
[ASIA/PAC/3, Rec. 10/19]
ATS inter-facility data communications
(AIDC) circuits
24. States should consider implementing the ATN
application AIDC in order to enable the exchange of ATS
messages for active flights related to flight notification,
flight coordination , transfer of control surveillance data
and free (unstructured) text data.
Air/ground communications
Aeronautical mobile service
and aeronautical mobile satellite service
Frequency utilization list.
25. States in the ASIA/PAC regions should
IV-4 ASIA/PAC BASIC ANP
coordinate, as necessary, with the ICAO Regional Office
all radio frequency assignments for both national and
inter-national facilities in the190–526.50 kHz, 108–117.975
MHz, 960–1215 MHz and 117.975–137 MHz bands. The
ICAO Regional Office, based on the information provided
for this purpose by the States, will issue Frequency Lists
Nos. 1, 2 and 3 at periodic intervals.
[ASIA/PAC/3, Conc. 11/4, 11/5 and 12/9]
HF en-route communications
26. States should be urged to coordinate on a
national basis with the appropriate interested authorities, a
programme directed towards achieving the elimination of
the interference currently being experienced on some of the
frequencies allocated to the Aeronautical Mobile (R)
Service in the ASIA/PAC regions. When reviewing
methods for developing such a national programme,
consideration should be given to the procedures in Article
S15 of the ITU Radio Regulations.
27. In the case of an unidentified interfering station,
States should notify the ICAO Regional Office concerned,
utilizing the procedure and report form developed by the
Fifth Session of the Communications Division (1954) and
updated by the Communications Divisional Meeting (1978).
The Harmful Interference Report Form is provided in
Attachment C. However, in the case of persistent harmful
interference to an aeronautical service which may affect
safety, it should be immediately reported to ICAO and to
the ITU, using the prescribed format, for appropriate action.
[ASIA/PAC/3, Conc. 11/6]
Air-ground elements of ATN
28. With the implementation of the air-ground
applications of ATN, it is important to ensure that transit
response times are kept to a minimum level so as not to
affect the overall response time that it takes for traffic such
as automatic dependent surveillance (ADS) reports and
controller-pilot data link communications (CPDLC)
messages to be delivered to their final destination. This also
reflects the need to ensure that critical ground links within
the ASIA/PAC regions are capable of handling this
information efficiently.
29. One important factor with air-ground traffic is
the generation of routing information caused by aircraft that
will move between various ATN routing domains. As
aircraft move through various coverage media and FIR
boundaries, the ATN routing backbone will be notified of
the changing routing data for each mobile aircraft in the
region. To allow this routing information to be propagated
within the region will require a minimum number of
backbone routers to be implemented which protect all other
ATN routers form being inundated with routing
information.
[ASIA/PAC ATN transition plan]
NAVIGATION
General
30. The plan and details of operational requirements
for radio navigation aids are contained in Table CNS 3 and
associated charts of Part IV of the FASID.
31. States should continue to provide ICAO with
information on their flight inspection activities for inclusion
in the ASIA/PAC Catalogue of Flight Inspection Units and
circulation to States in the ASIA/PAC regions and to the
ASIA/PAC Air Navigation Planning and Implementation
Regional Group (APANPIRG).
[ASIA/PAC/3, Conc. 12/8]
32. The development of the radio navigation aids
plan, and its subsequent documentation in relevant air
navigation plan (ANP) publications, defines the respective
radio navigation aid requirements at each location without
reference to discrete frequency assignments. The ICAO
Regional Office will continue to maintain its frequency
selection and co-ordination role, including the maintenance
and promulgation of Frequency Lists Nos. 1 and 2 in a
timely and periodic manner.
[ASIA/PAC/3, Conc. 12/9]
Radio navigation aid requirements
33. States that have not yet done so should install
VHF omnidirectional radio range (VOR) supplemented by
distance measuring equipment (DME) as the primary aid
for en-route navigation and, except in specified
circumstances, delete any parallel requirement for a
non-directional radio beacon (NDB) from the ANP.
[ASIA/PAC/3, Rec. 5/22]
CNS IV-5
SURVEILLANCE
General
34. The plan and details of operational requirements
for surveillance are contained in Table CNS 4A of Part IV
of the FASID.
35. Surveillance systems for terminal and en-route
ATC purposes should be installed, maintained and operated
at international aerodromes and en-route area control
centres whenever it is necessary to improve the safe and
expeditious handling of air traffic and wherever the traffic
density and associated complexity of operations, system
delays, meteoro-logical conditions and/or transition from
oceanic to continental airspace would justify these
installations.
[ASIA/PAC/3, Rec. 5/28]
36. Where different systems are used for navigation
and position determination within the same controlled
airspace, the ground facilities involved should be collocated
and/or orientated so as to provide compatible flight paths
and to ensure, as far as practicable, a fully integrated ATC
pattern.
[ASIA/PAC, Rec. 7/14]
37. The ASIA/PAC regions are characterised by the
use of:
a) secondary surveillance radar (SSR) Mode A, C and, in
the near future, Mode S in some terminal and
high-density continental airspace;
b) ADS in some parts of the ASIA/PAC regions; and
c) the diminishing use of primary radar.
38. ADS is becoming available over the oceanic and
continental airspace of the ASIA/PAC regions. SSR
(augmented as necessary with Mode S) will continue to be
used in terminal areas and in some high density airspace.
Automatic Dependent Surveillance (ADS)
Coordination of activities related
to the implementation of ADS
39. The introduction of air-ground data links,
together with sufficiently accurate and reliable aircraft
navigation systems, presents the opportunity to provide
surveillance services in areas lacking such services in the
present infrastructure, in particular oceanic areas and other
areas where the current systems prove difficult,
uneconomic, or even impossible, to implement. ADS is a
function for use by ATS in which aircraft automatically
transmit, via a data link, data derived from on-board
navigation systems. As a minimum, the data should include
the four-dimensional position. Additional data may be
provided as appropriate. The ADS data would be used by
the automated ATC system to present information to the
controller. In addition to areas which are at present devoid
of traffic position information other than pilot-provided
position reports, ADS will find beneficial application in
other areas including high-density areas, where ADS may
serve as an adjunct and/or backup for SSR and thereby
reduce the need for primary radar. Also, in some
circumstances, it may even substitute for secondary radar in
the future. As with current surveillance systems, the full
benefit of ADS requires supporting complementary
two-way pilot-controller data and/or voice communication
(voice for at least emergency and non-routine
communication).
40. States should closely cooperate in the
development of procedures for the implementation of ADS
in the ASIA/PAC regions and participate to the extent
possible in trials and demonstrations related to the
implementation of ADS.
[ASIA/PAC/3, Conc. 14/21]
Secondary surveillance radar (SSR)
Implementation of surveillance
systems
41. Implementation of surveillance systems should
be pursued as an enhancement to ATS where so required
and the use of SSR alone, in accordance with the
procedures in the Regional Supplementary Procedures
(Doc 7030), should be considered as a cost-effective
alternative to primary surveillance radar.
[ASIA/PAC/3, Rec. 14/20]
IV-A1
Attachment A
LANDLINE TELETYPEWRITER (LTT)
CIRCUIT PERFORMANCE
Instructions for use of the form
1. The serviceability of the circuit should be given to the
nearest 7½ minutes.
2. The copies of the form should be dispatched to the
other States concerned as soon as possible, but in no
case later than the fourteenth day of the following
month.
3. Data should be entered only for the reception over the
circuit concerned. When the circuit is “IN”, insert the
figure in the appropriate square. When the circuit is
“OUT”, insert the cause of outage according to the
“outage code”.
4. The serviceability percentage can be computed by
dividing the number of minutes the circuit is in
operation by the total in a particular month, and
multiplying by 100.
5. The term “outage” means communications circuit
failure.
6. When the term “other” is used to indicate outages on
the chart, additional information should be provided to
define the cause of the outage.
IV-A4 ASIA/PAC BASIC ANP
LANDLINE TELETYPEWRITER CIRCUIT PERFORMANCE CHART
Receiving station: % of circuit availability for the month:
Transmitting station: Circuit No.:
Month: Year:
Time DatesTime
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
31
0000 00
0100 01
0200 02
0300 03
0400 04
0500 05
0600 06
0700 07
0800 08
0900 09
1000 10
1100 11
1200 12
CNS IV-A5
Time DatesTime
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
31
1300 13
1400 14
1500 15
1600 16
1700 17
1800 18
1900 19
2000 20
2100 21
2200 22
2300 23
2400 24
Daily % Dai
ly
%
Outage legend:
IV-A6 ASIA/PAC BASIC ANP
Leased
circuit
Line between COM centre
and comon carrier terminal
Equipment RX
terminal COM centre
Equipment TX
terminal COM centre
Other
IV-B1
Attachment B
AFTN CIRCUIT LOADING STATISTICS
Instructions for use of the form
1. Originating station: Insert the name and four-letter
location indicator of the station reporting the statistics.
2. Correspondent station(s):Insert the name and four-letter
location indicator of the distant end station of the circuit
(in case of multipoint circuits, list all distant end
stations and their four-letter location indicators).
3. Signalling speed: Transmission speed in Baud or bits
per second.
4. Number of channels: List the number of channels on a
direct AFTN circuit between the originating and
correspondent stations indicated on the form. If there is
more than one channel on a circuit, data to be indicated
in the respective columns for each channel should be
added separately, and an average figure should be
indicated in the respective columns.
5. Average loading: Total the daily input/output
percentage, as applicable, by the number of days
sampled and enter the result as a percentage in the
respective column.
6. Date: Date that the traffic sample was taken
(dd/mm/yy).
7. Peak hourly: Insert data for the peak hour of each day
for both received (input) and transmitted (output) in the
respective columns.
8. Total daily: Total number of characters received and
sent for each day to be entered in the respective daily
input/output columns.
9. Percent hourly/daily: Calculate utilization sent and
received, hourly and daily.
a) To calculate hourly percentage, divide the peak hour
character count (input/output) separately by the
effective circuit capacity (listed below). Multiply
the result by 100. Enter this figure as the
percentage in the respective column.
b) To calculate daily percentage, divide the total daily
character count (input/output separately), by the
effective circuit capacity (listed below x 24).
Multiply the result by 100 and enter this figure as a
daily input/output percentage in the respective
columns.
c) The effective circuit capacities below are based on
the code set used.
ITA-2 Code
Signalling speed
(Baud)
Effective characters/hour
50
24 000
75
36 000
100
48 000
150
72 000
300
144 000
IV-B2 ASIA/PAC BASIC ANP
IA-5 Code, Asynchronous (1 stop bit)
Signalling speed
(bits/s)
Effective characters/hour
Without protocol
CAT B protocol (93%)*
300
108 000
100 400
600
216 000
200 880
1 200
432 000
401 760
2 400
864 000
803 520
4 800
1 728 000
1 607 040
9 600
3 456 000
3 214 080
IA-5 Code, Synchronic
Signalling speed
(bits/s)
Effective characters/hour
CAT B protocol (93%)*
HDLC (97%)**
2 400
1 004 400
1 047 600
4 800
2 008 800
2 095 200
9 600
4 017 600
4 190 400
X.25 Circuits
Signalling speed
(bits/s)
Maximum number of bytes
Per hour
Per day
9 600
4 320 000
103 680 000
64 000
28 800 000
691 200 000
* Actual characters per hour have been derated to 93 per cent to allow for protocol overhead.
** Actual characters per hour have been derated to 97 per cent to allow for protocol overhead.
CNS IV-B3
AFTN CIRCUIT LOADING STATISTICS
Originating station: (name)
Location indicator:
Correspondent station: (name)
Location indicator:
Signalling speed:
Total number of channels:
Average loading: Input % Output %
Date
AFTN centre / Station input
AFTN centre / Station output
Peak
hourly
Percent
hourly
Total
daily
Percent
daily
Peak
hourly
Percent
hourly
Total
daily
Percent
daily
IV-C1
Attachment C
HARMFUL INTERFERENCE REPORT FORM
This form should be used in cases of harmful interference with aeronautical services and only in those instances where the
procedure outlined in the ITU-R Radio Regulations has not produced satisfactory results. The form should only be submitted
after at least the sections marked with an asterisk have been completed.
* State or organization submitting report ...................................................................................................................................
* 1. Frequency of channel interfered with ..............................................................................................................................
* 2. Station or route interfered with ........................................................................................................................................
* 3. Is the interference persistent? ..........................................................................................................................................
* 3.1 Date, time, altitude and position at which interference was observed:
Date
Time (GMT) Altitude Position
Note.— Report forms should not be sent unless the interference has been observed a sufficient number of times to
justify setting international administrative machinery into motion, or unless it is considered to be endangering a radio
navigation or safety service.
4. Has your administration already applied, regarding this case of interference, any part(s) (state which) of the ITU
procedures laid down in Article S15 of the ITU-R Radio Regulations?
.........................................................................................................................................................................................
* 5. Call sign of IS (IS = interfering station) (See note below.) ...........................................................................................
6. Name of IS
corresponding to the call sign .......................................................................................................................
7. Notified frequency on which IS
should operate (if known) .............................................................................................
8. (a) Approximate frequency of IS ............................................................... kHz/MHz (circle applicable abbreviation)
(b) Strength of IS
(QSA or SINPFEMO — See ICAO Doc 8400) ..............................................................................
IV-C2 ASIA/PAC BASIC ANP
9. Class of emission of IS ....................................................................................................................................................
10. Language used by IS .......................................................................................................................................................
11. Call sign of station in communication with IS
.................................................................................................................
Note.— If the call sign referred to in 5 could not be received, or if the call sign received is not in the international series
and cannot be interpreted, the report form should not be sent unless at least one of the questions under 12, 13 and 14 can be
answered.
12. Location of the IS
(accurate or approximate coordinates) ...............................................................................................
13. Country where interfering station is believed to be located .............................................................................................
14. Bearing (in degrees true) of the IS
(with indication of location of D/F station) ..............................................................
ITU DEFINITION OF HARMFUL INTERFERENCE
Harmful interference: interference which endangers the functioning of a radionavigation service or of other safety
services or seriously degrades, obstructs, or repeatedly interrupts a radiocommunication service operating in accordance
with these Regulations.
