AERONA

UTICAL COMMUNICATIONS PANEL (ACP)

WORKING GROUP OF THE WHOLE

FOURTH MEETING

Montreal, 14 to 16 September 2011

REPORT OF THE FOURTH MEETING

1. AGENDA ITEM 1: PROGRESS OF WORK WITHIN ACP WGs I (IPS), M (MAINTENANCE) AND F (FREQUENCY)

1.1 Under this agenda item, the meeting reviewed WPs #10, #11 and #12. These were reports on progress made since WGW/3 by WGs I, M and F respectively. The meeting then reviewed WPs #3, #6, #7, #23 and #24, which contain proposed SARPs and Manual updates. Agreed updates can be found in Appendices A and B to this report. Update to be carried forward to the next ACP WG-F (Dakar 10 – 14 Oct 2011) is contained in Appendix C.

1.2 Note that all documents relevant to the work of the three Working Groups are accessible on the ACP webpage at http://www.icao.int/anb/panels/acp.

1.3 Summary of ACP WG-I Activities

1.3.1 The Secretary presented a report on the progress of ACP WG-I on behalf of the Rapporteur, Mr. Liviu Popescu, who was not able to attend this meeting.

The work programme for WG-I had been updated in 2010 as reflected by the Major Task 1, listed below:

Major task 1: Expected outcome -- Implementation of ATN/IPSWorking Group IPS (Internet Protocol Suite)

ANNEX 10 — VOLUME V 4-1 1/11/01

International Civil Aviation Organization

REPORT

ACP-WGW04/AI-1

2011-09-16

Output: Implementation manual (guidance material) ongoinga. Autonomous System numberingb. IPv6 addressing planc. Security protocols

Policy managementKey exchange

d. Transition guidance

ICAO material on Voice over Internet Protocol (VoIP)a. VoIP additions to ATN/IPS Manual completed

1.3.2 Three meetings of WG-I have been held since WG-W/3.

1.3.3 The Manual for the ATN using IPS Standards and Protocols (Doc 9896, Edition 2 was finalised to the extent possible in July 2011, see WP#24. The new edition includes VoIP requirements through reference to the documents developed by EUROCAE WG67. This is in line with the direction from ANC, to reference external mature standards for VoIP requirements, rather than developing standards at ICAO. The work on Security could not be completed until key States have determined their security policy and resulting requirements. This justifies a further extension of the schedule from that anticipated at ACP WG-W/3 in January 2010.

1.3.4 The remaining tasks for ACP WG-I have been identified as follows:

Consideration of a consistent addressing scheme and if needed, the acquisition of a large IPV6 addresses allocation from IANA to allow consistency in address allocation by ANSPs and Regions.

Development of Network Architecture Design Guidance for the IPS (IPv6) network, including regional addressing assignment, subnet addressing, aircraft addressing, routing infrastructure, routing protocol, network segmentations, regional interconnect designs, etc.

Development of PKI and IPSec Implementation Guidance to ensure that the key fields are formatted and used consistently which is necessary for the interoperability of authentication and security services between ANSP’s and regions.

The definition of a consistent Aircraft and Ground System Naming/Identity for PKI use as the authentication identifier.

The definition of an Aircraft and Ground System IPS Domain Name System structure for both the aircraft and ground systems. This should also include the required design guidance for “ATN Root Name Server” infrastructure to be setup between the ANSPs.

Development of IPS DNS Implementation Guidance for interfacing the “ATN Root Name Servers”, for implementing DNSSec both within and between ANSPs, the creation of “service names”, and IPv4/IPv6 resolution services.

Development of IPv4 – IPv6 Transition Guidance to ensure that a minimal set of transition services are supported to minimize interoperability and to ensure that supported transition services are implemented similarly between ANSPs/regions.

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As a result of the WGI#14 outcome, it is proposed to address the following items too:

Development of technical provisions for the support of Directory Services over IPS and guidance material on its use and implementation. The Directory Service is an on-line tool that can directly impact operation of the network security, ATSMHS, and other application. The ICAO is currently utilizing an off-line tool, called ATS Messaging Management Centre (AMC).

Evaluation of ICAO Doc. 9855 Guidelines on the use of Public Internet for Aeronautical Applications, to determine the feasibility of using the public internet for Aeronautical Fixed Service (AFS) messages distribution. The AFS has been defined as time critical Air Traffic service while the existing utilization of public internet for distribution of OPMET and World Area Forecast System (WAFS) is defined as non-time critical Air Traffic service.

The above tasks require support from Members States’ personnel with IPS skills. ICAO ACP Secretariat will send a memo to all ACP members, calling for experts in support of the timely completion of these tasks.

1.4 Summary of ACP WG-M Activities

1.4.1 Mr. Brent Phillips, the Rapporteur of ACP WG-M summarised the activities of the group since January 2010. ACP Working Group M has been tasked with the Maintenance of SARPS and Guidance Material for communications Systems. This includes Manuals on the detailed specifications for ATN/OSI, VDL Modes 2 and 4, and the manuals for AMS(R)S.

1.4.2 WG-M has held three meetings over the past two years.

1.4.3 ATN/OSI Document 9880 update status.

1.4.3.1 There has been considerable discussion on the Air/Ground portion of ATN Security, to be contained in the new Part IV-B. It was observed that certain Ground/Ground and Air/Ground applications depend on Part IV-B and that there were different program needs for Air/Ground Security in EUROPE and the US. In addition, the US was investigating an alternative to the ULCS part of Air/Ground security. In order to progress this work further, the WG-M agreed that further coordination was required between the FAA and EUROCONTROL under the recently approved FAA/SJU Memorandum of Understanding (MOU) to address any outstanding issues. Further validation considered necessary would then be completed and the results coordinated with SC-214/WG-78 and EUROCONTROL before submission to WG-M for approval. This work will be completed in a timeframe to achieve approval for inclusion in 9880 to meet the scheduled need of the future air-ground communications systems.

1.4.4 Updates to VDL Documents

1.4.4.1 Changes to the VDL Mode 2 Standard Doc 9776 are currently being progressed within WG-M. Once finalized, these changes will provide support for capabilities being considered for multi-frequency operations. EUROCONTROL validation of multi-frequency operation of VDL M2 will provide further updates to Doc 9776 as needed in the future.

1.4.4.2 Various updates to the SARPs and manual on VDL Mode 4 (Doc 9816) have been finalized. Those were presented and discussed separately under WPs #3, #6, #7. See also section 1.6 of this report.

1.4.5 Future updates to AMS(R)S SARPs and associated technical manuals.

1.4.5.1 EUROCONTROL is carrying out activities within their NEXUS group to develop a consolidated proposal for an update of the AMS(R)S SARPs. This work is being performed with the objective of defining a consolidated proposal for an update of the SARPS which will focus mainly on performance.

1.4.5.2 It was noted that the INMARSAT SwiftBroadband system was being modified in order to be SARPS compliant and that because of the significant differences between this and the INMARSAT “Classic” system, a new section would be needed in the AMS(R)S Manual.

1.4.6 AeroMACS Status Updates

1.4.6.1 WG-M has received continuous updates on the status of on-going performance and validation testing being performed on the Aeronautical Mobile Airport Communications System (AeroMACS). The AeroMACS profile has been developed jointly by RTCA SC-223 and EUROCAE WG-82. The document was recently approved by the RTCA Program Management Committee.

1.4.7 Maintenance of UAT Documents

1.4.7.1 A number of changes to Doc 9861 (Manual of UAT) were presented and approved during WG-M/16. These same changes were also being progressed by the Aeronautical Surveillance Panel (ASP), to be applied to 1090 Mode-S Extended squitter,. The changes included allowance for the use of a bottom antenna only for ADS-B out. The changes were being included in the new ADS-B rule being included in Federal Aviation Regulations Part 91.225 and will become mandatory from January 1, 2020.

1.5 Summary of ACP WG-F Activities

1.5.1 Mr. Steve Mitchell, the Rapporteur of ACP WG-F, presented brief details of the activities within WG-F. WG-F is tasked with addressing all ICAO spectrum management issues including assisting in the development of the ICAO positions for the International Telecommunications Union (ITU) World Radiocommunication Conferences (WRCs) and material for input into various international radio regulatory fora.

1.5.2 WG-F has held 3 meetings since ACP WG-W/3 at the following ICAO Regional Offices: Mexico City, Cairo and Paris. In line with the objectives of the ACP Work Programme, each of the WG-F meetings was preceded by a spectrum seminar related to preparation for the ITU WRC-12. These proved to be very successful with good participation from the regions. The next meeting of WG-F and the last to be held before WRC-12, will be held in Dakar, Senegal from the 6 – 14 October 2011 and will follow the same format as used for the previously three meetings.

1.5.3 In the continuing preparation for WRC-12 WG-F have been working on two particular items which are of interest to the ACP.

1.5.3.1 The first relates to WRC-12 Agenda Item 1.7 which is looking at the long-term spectrum availability and access for AMS(R)S by the aeronautical community. A number of methods are now available to satisfy this agenda item however there is no clear method providing the best approach. At the latest meeting of WG-F the meeting agreed to form a correspondence group under Mr Suzuki (Japan) in order to develop a solution that would address the needs of aviation and ICAO.

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1.5.3.2 The second item of particular interest is with regards to WRC-12 Agenda Item 1.4 Resolution 420 which is looking at spectrum allocations for the 5GHz AeroMACS airport surface LAN. The main issue here is whether the spectrum allocation made at WRC-07 is adequate to meet the requirements of the system. As the system concept continues to develop greater safety related mobile facilities are envisaged but it is unclear whether these can be completely accommodated within the 59MHz allocation. Recently it has been suggested within the ITU-R by interests outside aviation that the AeroMACS system should look at using LTE (Long Term Evolution) technology as the proponents of such a system suggest it is far more spectrally efficient than WiMax. This view is not supported by the ACP WG-F. See also discussion in section 1.5.7.1 below.

1.5.4 Update to ICAO RF Handbook (ICAO Doc. 9718). Material on frequency planning criteria was received within WG-F which will be useful for inclusion in Volume II of the RF handbook. Since the group now has a basis to move on with the development of the second volume, a correspondence group has recently been formed under Robert Witzen in order to produce suitable material for the volume. It is expected that Volume II will be available towards the end of next year. As a further outcome of this work, the correspondence group is also looking into updates to the SARPs contained in Annex 10, Vol V, Chapter 4. See also section 1.6.3 and appendix C.

1.5.5 Interference from non-aeronautical sources. WG-F reported two potential future sources of interference that are of particular interest to aviation.

1.5.5.1 The first relates to the operation of a terrestrial broadband service known as the Complimentary Ground Component (CGC) which is being proposed for the mobile satellite service band where AMS(R)S operates and is adjacent to the GPS L1 frequency band. Given the proposed high radiated power for CGC the possibility for interference is significant. WG-F is currently monitoring studies being undertaken in the USA.

1.5.5.2 The other area of potential interference which is also being monitored relates to the activities by a number of States to identify large amounts of spectrum for broadband mobile services. A number of frequency bands used by aviation have been identified within these States as offering potential solutions and cover aeronautical communication, navigation and surveillance spectrum.

1.5.6 Annex 10 maintenance on spectrum related issues. WG-F has continued to successfully liaise with other panels and working groups. One area that has been identified where some improvement could be made is with respect to the maintenance of Annex 10 Volume V. Since this volume deals with spectrum and frequency issues, any proposed changes need to be considered by WG-M and then agreed by WG-F. To remove a step from this process, it was suggested that WG-F could take on the responsibility for the maintenance of Volume V. Since Volume V contains material related to communications, navigation and surveillance disciplines, WG-F through the Secretariat could continue to liaise with other panels particularly where changes are needed to other Annex 10 volumes that are of a spectrum/frequency management nature

1.5.7 In the ensuing discussions, the following points were addressed and agreed:

1.5.7.1 As regards the issue of LTE (Long Term Evolution) (see section 1.5.3.2 above) as a potential candidate technology for AeroMACS, this is clearly not feasible. Commercial development will always outpace aviation. Several years of research/development and standardization are required to ascertain and ensure that a system/technology is appropriate for the stringent safety requirements unique to aviation. The adoption and further development of the IEEE 802.16e standard for aviation is an example of such a long-term effort. LTE on the other hand, currently being developed for consumer grade 4G wireless telephony and broadband, is not a fully mature protocol at this time. Hence aviation can only continue with consideration of AeroMACS, based on the WiMAX IEEE 802.16(2009) standard.

1.5.7.2 As regards Annex 10, Vol V, it was agreed that ACP WG-F take over maintenance of this volume. See also discussion on WP#23 in section 1.6.3 below.

1.6 Other papers, containing deliverables from WGs I, M and F.

1.6.1 WPs #3 and #6were introduced by the Secretary. These papers contained amendment proposals to Annex 10, Vol III, Part I Chapter 6. The rationale for the first amendment proposal was to bring the SARPs for VDL Mode 4 in line with an update made to the ITU Radio Regulations during WRC-07. The rationale for the second amendment proposal was to indicate support to the ATN/IPS. The meeting agreed to the amendment proposals with one minor editorial modification. The amendment proposals are contained in Appendix A to the report on this agenda item.

1.6.2 WP#7 , introduced by the Secretary, proposed updates to Doc 9816, the VDL Mode 4 Manual. These updates, approved by ACP WG-M, are the result of two things; a) operational experiences calling for adjustments to various operating parameters, and b) changes needed to ensure consistency with the ITU Radio Regulations (see also WP#3). Amendment proposals were agreed and are contained in Appendix B to the report on this agenda item.

1.6.3 WP#23 , introduced by the Secretary, proposes a method to expedite updates to Annex 10, Vol V, Chapter 4, as indicated in 1.5.4 above. A number of updates, as developed and discussed in a correspondence group under ACP WG-F were introduced briefly. It was proposed to the meeting that to facilitate the progress of this work, the amendment proposals should be further discussed at the upcoming meeting of ACP WG-F in October, with the view of finalizing the work on the proposals. Once agreed by the ACP WG-F, the updates would be circulated amongst ACP members by email correspondence for final approval. While a potential issue with a suggested protection date of 2025 in the current update proposal was raised and will be further discussed in WG-F, the ACP WG-W/4 agreed to this methodology to progress the work. The draft amendment proposals are contained in Appendix C to the report on this agenda item.

WP#24, introduced by the Secretary, contains amendment proposals to Doc 9896, as agreed by ACP WG-I in July. Secretary will clarify the material with regards to FAA requirements and reinforce that the document relies on EUROCAE Ed137/138 as a technical reference.

Actions:

1/1 Secretary to process agreed SARPs updates, as contained in Appendix A.

1/2 Secretary to process agreed updates to Manual on VHF Digital Link (VDL) Mode 4 (Doc 9816 AN/448), as contained in Appendix B.

1/3 ACP WG-F to progress and finalize the development of updates to Annex 10, Vol V, along the lines indicated in Appendix C. Secretary to liaise with ACP WG-F.

1/4 Secretary to clarify the amendment proposals to which were agreed to Doc 9896 by ACP WG-I in July, in particular with regards to FAA requirements, and reinforce that the document relies on Eurocae ED137/138 as a technical reference.

1/5 Once 1/4 above is completed, Secretary to process agreed updates to Doc 9896.

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Appendix A

Amendment proposal to Annex 10, Vol III:

Current provisions for VDL Mode 4 tuning range:

The requirements for tuning range of VDL Mode 4 radios are defined in the VDL SARPs in Annex 10 Volume III, Part I, section 6.9.2:

6.9.2 VDL Mode 4 radio channels6.9.2.1 VDL MODE 4 STATION FREQUENCY RANGE

6.9.2.1.1 Transmitter/receiver tuning range. A VDL Mode 4 transmitter/receiver shall be capable of tuning to any ofthe 25 kHz channels from 117.975 MHz through 137 MHz. The transmitter shall have a means for the tuning range to be restricted to a narrower range.

Note.— Operational conditions or certain applications may require the equipment to be operated in a narrowerfrequency range.

6.9.2.1.2 Recommendation.— A VDL Mode 4 transmitter/receiver should be capable of tuning to any of the 25 kHzchannels from 108 to 117.975 MHz.

Note.— The band 108–117.975 MHz may be utilized in accordance with the relevant provisions of the ITU Radio Regulations.

6.9.2.1.3 Simultaneous reception. A VDL Mode 4 station shall be capable of receiving two channels simultaneously.6.9.2.1.4 Recommendation.— A VDL Mode 4 station should be capable of receiving additional channelssimultaneously as required by operational services.

Support to surveillance functions in the band 108-117.975 MHz was introduced in the ITU Radio Regulation at the World Radio Conference 2003 (WRC2003):

“The band 108–117.975 MHz may also be used by the aeronautical mobile (R) service on a primary basis, limited to systems that transmit navigational information in support of air navigation and surveillance functions in accordance with recognized international standards. Such use shall be in accordance with Resolution 413 (WRC-03) and shall not cause harmful interference to nor claim protection from stations operating in the aeronautical radionavigation service which operate in accordance with international aeronautical standards. (WRC-03)”

At the World Radio Conference 2007 (WRC2007) the allocation in the band 108-117.975 Mhz were adjusted to: Note. — “Additional allocation:  the band 108-117.975 MHz is also allocated on a

primary basis to the aeronautical mobile (R) service, limited to systems operating in accordance with recognized international aeronautical standards. Such use shall be in accordance with

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Resolution 413 (Rev.WRC-07). The use of the band 108-112 MHz by the aeronautical mobile (R) service shall be limited to systems composed of ground-based transmitters and associated receivers that provide navigational information in support of air navigation functions in accordance with recognized international aeronautical standards.     (WRC-07)”

The current provisions in the ITU Radio Regulations limit the available spectrum to the band 112 – 117.975 MHz and it is appropriate to ensure full compliance with the ITU Radio Regulation.

Changes to the ICAO VDL Mode 4 Provisions on tuning range:

To reflect the current conditions of the Radio Regulations in the provisions of Annex 10, the following changes to Annex 10 Volume III, Part I, section 6.9.2 are proposed:

6.9.2 VDL Mode 4 radio channels6.9.2.1 VDL MODE 4 STATION FREQUENCY RANGE

6.9.2.1.1 Transmitter/receiver tuning range. A VDL Mode 4 transmitter/receiver shall be capable of tuning to any ofthe 25 kHz channels from 112 MHz through 137 MHz.

Note.— Operational conditions or certain applications may require the equipment to be operated in a narrowerfrequency range.

6.9.2.1.2 Simultaneous reception. A VDL Mode 4 station shall be capable of receiving two channels simultaneously.6.9.2.1.3 Recommendation.— A VDL Mode 4 station should be capable of receiving additional channelssimultaneously as required by operational services.

In Annex 10 Volume III, Part I , Section “Tables for Chapter 6” on page I-6-27, Table 6-5 “VDL Mode 4 operating frequencies between 108.0-111.975 MHz” should be deleted and numbering of subsequent tables adjusted.

Changes to the VDL Mode 4 Provisions to indicate ATN/IPS compatibility:

To reflect the current capability of the VDL Mode 4 data link sub-network, Annex 10 Volume III, Part I, section “6.9.3 System capabilities” should be updated as proposed in the following paragraphs. It is proposed that paragraph 6.9.3.1 is adjusted as follows:

Present text:6.9.3.1 ATN compatibility. The VDL Mode 4 system shall support ATN-compliant subnetwork services for surveillance applications.

Updated text:

6.9.3.1 ATN compatibility. The VDL Mode 4 system shall support ATN/IPS compliant subnetwork services.

6.9.3.1.1 Recommendation: Where required, VDL Mode 4 may be implemented using ATN/OSI protocols.  Note: VDL Mode 4 provides a seamless transfer of data between ATN/IPS ground networks and ATN/IPS aircraft networks. Interoperability with ATN/OSI networks is expected to be arranged prior to implementation. VDL Mode 2 and 3 provide ATN/OSI compliant subnetworks

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Appendix B

Amendment proposal to the Manual on VHF Digital Link (VDL) Mode 4 (Doc 9816 AN/448):

Below are the three Chapters to be updated, inserted as objects (click on icons to open). Updates are shown in redline/strikeout format

Appendix C

Draft Amendment Proposals to Annex 10, Vol V, to be addressed further by ACP WG-F/25:

CHAPTER 4.    UTILIZATION OF FREQUENCIES ABOVE 30 MHz4.1    Utilization in the band

117.975 – 137 MHz

Note: Details pertaining to the allocation and use of the frequency band 117.975 – 137 MHz to the aeronautical mobile (R) service and the frequency bands 108 – 117.975 MHz and 960 – 1215 MHz to the aeronautical radionavigation service are in the Radio Regulations of the International Telecommunication Union and in the ICAO Handbook on radio frequency spectrum requirements for civil aviation (Doc. 9718)

Introduction

The band 118 – 132 MHz was allocated in 1947 by the Atlantic City ITU Radio Conference, and again in 1959 by the Geneva Conference, but with extension downwards to 117.975 MHz, for the exclusive use by the aeronautical mobile (R) service.

ITU Radio Conferences subsequent to 1947 also made provisions for the use of the band 132 – 136 MHz for the aeronautical mobile (R) service under conditions which vary for the different ITU Regions, countries or combination of countries. The utilization of this band has been included in the Allotment Table in this chapter. The ITU World Administrative Radio Conference (1979) made provisions for the use of the band 136 – 137 MHz by the aeronautical mobile (R) service, subject to conditions of Nos. S5.203, S5.203A and S5.203B of the Radio Regulations. The use of frequencies in the 136 – 137 MHz part of the band must take account of the conditions contained in these notes. In the utilization of these bands, States’ attention is drawn to the possibility of harmful radio interference from non-aeronautical sources of radio frequency energy and the need to take appropriate measures to minimize its effects.

This chapter Section 4.1 deals with Standards and Recommended Practices (SARPs) relating to theis use of the band 117.975 – 137 MHz and includes matters pertaining to the selection of particular frequencies for various aeronautical purposes. These SARPs Standards are introduced by the following preface, which sets out the principles upon which the utilization of this frequency band VHF on a worldwide basis, with due regard to economy, is being has been planned.

Preface

The utilization of the band 117.975 – 137 MHz VHF on a worldwide basis with due regard to economy and practicability requires a frequency assignment plan that will take into account:

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Comment: The paragraphs above are proposed to be deleted since the proposed note does not refers to material concerning the utilization of the band 117.975 – 137 MHz and the above material is already incorporated in Doc. 9718.

Comment: The proposed changes above are editorial

Comment: This note refers to relevant documentation on the allocation and use of the frequency bands which are addressed in this Chapter.

a) the need for an orderly evolution towards improved operation and the required degree of worldwide standardization;

b) the desirability of providing for an economic transition from present utilization to optimum utilization of the frequencies available, taking into account the maximum possible utilization of existing equipment;

c) the need to provide for coordination between international and national utilization so as to ensure mutual protection from interference;

d) the need for providing a framework for the integrated development of Regional Plans;

e) the desirability of incorporating in any group of frequencies to be used those now in use for international air services;

f) the need for keeping the total number of frequencies and their grouping in appropriate relation to the airborne equipment known to be widely used by international air services;

g) a requirement for the provision of a single frequency that may be used for emergency purposes on a world-wide basis and, also, in certain regions, for another frequency that may be used as a common frequency for special purposes; and

h) the need for providing sufficient flexibility to allow for the differences in application necessitated by regional conditions.

4.1.1    General allotment offrequency band 117.975 – 137 MHz

Note.— The frequency assignment plan includes a general Allotment Table that subdivides the complete band 117.975 – 137 MHz, the chief subdivisions being the bands of frequencies allocated to both national and international services, and the bands allocated to national services. Observance of this general subdivision should keep to a minimum the problem of coordinating national and international application.

4.1.1.1    The block allotment of the frequency band 117.975 – 137 MHz shall be as shown in Table 4-1.

Table 4-1. Allotment table

Block allotment ofFrequencies (MHz)

Worldwide utilization Remarks

a) 118 – 121.4 inclusive

International and NationalAeronautical Mobile Services

Specific international allotments will be determined in the light of regionalagreement. National assignments are covered by the provisions in 4.1.5.9.

b) 121.5 Emergency frequency In order to provide a guard band for the protection of the aeronautical emergency frequency, the nearest assignable frequencies on either side of 121.5 MHz are 121.4 MHz and 121.6 MHz, except that by regional agreement it may be decided that the nearest assignable frequencies are 121.3 MHz and 121.7 MHz.

c) 121.6 – 21.9917inclusive

International and NationalAerodrome SurfaceCommunications

Reserved for ground movement, pre-flight checking, air traffic servicesclearances, and associated operations.

d) 122 – 123.05inclusive

National Aeronautical Mobile Services

Reserved for national allotments.

e) 123.1 Auxiliary frequency SAR See 4.1.4.1.f) 123.15 – 123.6917inclusive

National Aeronautical Mobile Services

Reserved for national allotments, with the exception of 123.45 MHz which is also used as the worldwide air-to-air communications channel (see g)).

Comment: It is assumed that “a plan” refers to the frequency assignment plan that is developed through Regional frequency assignment planning.

g) 123.45 Air-to-air communications Designated for use as provided for in 4.1.3.2.1.h) 123.7 – 129.6917inclusive

International and NationalAeronautical Mobile Services

Specific international allotments will be determined in light of regional agreement. National assignments are covered by the provisions in 4.1.5.9.

i) 129.7 – 130.8917inclusive

National Aeronautical Mobile Services

Reserved for national allotments but may be used in whole or in part, subject to regional agreement, to meet the requirements mentioned in 4.1.8.1.3.

j) 130.9 – 136.875inclusive

International and NationalAeronautical Mobile Services

Specific international allotments will be determined in light of regional agreement. National assignments are covered by the provisions in 4.1.5.9.(See the Introduction to 4.1 regarding the band 132 – 137 MHz.)

k) 136.9 – 136.975inclusive

International and NationalAeronautical Mobile Services

Reserved for VHF air-ground data link communications.

4.1.1.2    Recommendation.— In the case of the band 136 – 137 MHz, international applications have not yet been agreed, and these frequencies should be brought into use on a regional basis where and in the manner required.

4.1.2    Frequency separation and limitsof assignable frequencies

Note.— In the following text the channel spacing for 8.33 kHz channel assignments is defined as 25 kHz divided by 3 which is 8.333 ... kHz.

4.1.2.1    The minimum separation between assignable frequencies in the aeronautical mobile (R) service shall be 8.33 kHz.

Note.— It is recognized that in some regions or areas, 100 kHz, 50 kHz or 25 kHz channel spacing provides an adequate number of frequencies suitably related to international and national air services and that equipment designed specifically for 100 kHz, 50 kHz or 25 kHz channel spacing will remain adequate for services operating within such regions or areas. It is further recognized that assignments based on 25 kHz channel spacing as well as 8.33 kHz channel spacing may continue to co-exist within one region or area.

4.1.2.2    Until at least 1 January 20252005, DSB-AM equipment specifically designed for 25 kHz channel spacing shall be safeguarded with respect to its suitability for the aeronautical mozbile (R) service (AM(R)S) except in those regions or areas where regional agreement permits the use of equipment specifically designed for 8.33 kHz channel spacing or for VDL Mode 3 when used for air-ground voice communications.

4.1.2.2.1    Requirements for mandatory carriage of equipment specifically designed for 8.33 kHz channel spacing shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation timescales for the carriage of equipment, including the appropriate lead time.

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Comment: All Regions (except in parts of Europe) have adopted 25 kHz channel spacing as the standard. In general, no specific measures are in place to accommodate equipment specifically designed for 100 kHz or 50 kHz channel spacing. It might be more appropriate to modify 4.1.2.1 to make the frequency separation of 25 kHz as the Standard, with 8.33 kHz channel spacing being introduced on the basis of a Regional Agreement. (See also 4.1.2.2.1)

Comment. With regard to the sub-division of the band in allotments for national aeronautical mobile services it should be noted that the sub-bands allotted for national use only are in all Region also used for international frequency assignments. As a result, the deletion of the national / international allotments should be considered. Paragraph 4.1.5.9 is proposed to be deleted

Comment: The use of the band 136 – 137 MHz for air/ground voice communications should be based on a Regional agreement and is subject to mandatory carriage of equipment that can tune into this band. The use of this band for air/ground data for VDL Mode 2 and VDL Mode 4 is already agreed in all Regions.

Note.— No changes will be required to aircraft systems or ground systems operating solely in regions not using 8.33 kHz channel spacing.

4.1.2.2.2    Until at least 1 January 20252005, equipment specifically designed for 8.33 kHz channel spacing shall be safeguarded with respect to its suitability for the AM(R)S.

4.1.2.2.3    Requirements for mandatory carriage of equipment specifically designed for VDL Mode 2, VDL Mode 3 and VDL Mode 4 shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation timescales for the carriage of equipment, including the appropriate lead time.

4.1.2.2.3.1    The agreement indicated in 4.1.2.2.3 shall provide at least two years’ notice of mandatory carriage of airborne systems.

4.1.2.2.4    Until at least 1 January 20252010, equipment specifically designed to the VDL Mode 3 and VDL Mode 4 SARPs shall be safeguarded with respect to its suitability for the AM(R)S.

4.1.2.3    In the band 117.975 – 137 MHz, the lowest assignable frequency shall be 118.000 MHz and the highest 136.975 MHz.

4.1.2.4    In regions where 25 kHz channel spacing (DSB-AM and VHF digital link (VDL)) and 8.33 kHz DSB-AM channel spacing are in operation, the publication of the assigned frequency or channel of operation shall conform to the channel contained in Table 4-1 (bis).

Note.— Table 4-1 (bis) provides the frequency channel pairing plan which retains the numerical designator of the 25 kHz DSB-AM environment and allows unique identification of a 25 kHz VDL and 8.33 kHz channel.

4.1.3    Frequencies used for particular functions

4.1.3.1    Emergency channel

4.1.3.1.1    The emergency channel (121.5 MHz) shall be used only for genuine emergency purposes, as broadly out-lined in the following:

a) to provide a clear channel between aircraft in distress or emergency and a ground station when the normal channels are being utilized for other aircraft;

Table 4-1 (bis).    Channelling/frequency pairing

Frequency(MHz)

Timeslot*

Channelspacing (kHz) Channel

118.0000 25 118.000

118.0000 A 25 118.001118.0000 B 25 118.002118.0000 C 25 118.003118.0000 D 25 118.004

118.0000 8.33 118.005118.0083 8.33 118.010

Comment: There is currently no provision to arrange for mandatory carriage of VDL Mode 2 in Annex 10. The (expired) date of 1 January 2005 in some provisions above is proposed to be extended to 2025.

Frequency(MHz)

Timeslot*

Channelspacing (kHz) Channel

118.0167 8.33 118.015

118.0250 A 25 118.021118.0250 B 25 118.022118.0250 C 25 118.023118.0250 D 25 118.024

118.0250 25 118.025

118.0250 8.33 118.030118.0333 8.33 118.035118.0417 8.33 118.040

118.0500 25 118.050

118.0500 A 25 118.051118.0500 B 25 118.052118.0500 C 25 118.053118.0500 D 25 118.054

118.0500 8.33 118.055118.0583 8.33 118.060118.0667 8.33 118.065

118.0750 A 25 118.071118.0750 B 25 118.072118.0750 C 25 118.073118.0750 D 25 118.074

118.0750 25 118.075

118.0750 8.33 118.080118.0833 8.33 118.085118.0917 8.33 118.090

118.1000 25 118.100

etc.

* Time slot indication is for VDL Mode 3 channels. (Ref. Annex 10, Volume III, Part I, Chapter 6 for characteristics of VDL Mode 3 operation)

b) to provide a VHF communication channel between aircraft and aerodromes, not normally used by international air services, in case of an emergency condition arising;

c) to provide a common VHF communication channel between aircraft, either civil or military, and between such aircraft, and surface services, involved in common search and rescue operations, prior to changing when necessary to the appropriate frequency;

d) to provide air-ground communication with aircraft when airborne equipment failure prevents the use of the regular channels;

e) to provide a channel for the operation of emergency locator transmitters (ELTs), and for communication between survival craft and aircraft engaged in search and rescue operations;

f) to provide a common VHF channel for communication between civil aircraft and intercepting aircraft or intercept control units and between civil or intercepting aircraft and air traffic services units in the event of interception of the civil aircraft.

1/11/01 4-16

Comment: It is assumed that ELT’s on 121.5 are still in operation (but may no longer be monitored by COSPAS/SARSAT)

Note 1.— The use of the frequency 121.5 MHz for the purpose outlined in c) is to be avoided if it interferes in any way with the efficient handling of distress traffic.

Note 2.— The current Radio Regulations permit the use of make provisions that the aeronautical emergency frequency 121.5 MHz may also be used by mobile stations of the maritime mobile service, using A3E emission to communicate on this frequency for distress and urgency safety purposes only with stations of the aeronautical mobile service (RR S5.200 and Appendix S153, Part A2).

4.1.3.1.2    The frequency 121.5 MHz shall be provided at:

a) all area control centres and flight information centres;

b) aerodrome control towers and approach control offices serving international aerodromes and international alternate aerodromes; and

c) any additional location designated by the appropriate ATS authority,

where the provision of that frequency is considered necessary to ensure immediate reception of distress calls or to serve the purposes specified in 4.1.3.1.1.

Note.— Where two or more of the above facilities are collocated, provision of 121.5 MHz at one would meet the requirement.

4.1.3.1.3    The frequency 121.5 MHz shall be available to intercept control units where considered necessary for the purpose specified in 4.1.3.1.1 f).

4.1.3.1.4    The emergency channel shall be guarded continuously during the hours of service of the units at which it is installed.

4.1.3.1.5    The emergency channel shall be guarded on a single channel simplex operation basis.

4.1.3.1.6    The emergency channel (121.5 MHz) shall be available only with the characteristics as contained in Annex 10, Volume III, Part II, Chapter 2 for equipment with 25 kHz channel spacing.

4.1.3.2    Air-to-air communications channel

4.1.3.2.1    An air-to-air VHF communications channel on the frequency of 123.45 MHz shall be designated to enable aircraft engaged in flights over remote and oceanic areas out of range of VHF ground stations to exchange necessary operational information and to facilitate the resolution of operational problems.

Note.— Use of the air-to-air channel can cause interference to and from aircraft using the same frequency for air-ground communications.

4.1.3.2.2    In remote and oceanic areas out of range of VHF ground stations, the air-to-air VHF communications channel on the frequency 123.45 MHz shall be available only with the characteristics as contained in Annex 10, Volume III, Part II,

Comment: Note 1 to 4.1.8.1.1.1 indicates that frequencies in the bands 121.425 – 121.575 MHz and 123.075 – 123.125 MHz are not available for assignment to channels of less than 25 kHz band width. For the emergency and the auxiliary frequencies this provision should have the status of a Standard (see also 4.1.4.2) . Consideration could be given to reduce the size of the guard bands around these frequencies.

Chapter 2.

4.1.3.3    Common signalling channel. The frequency 136.975 MHz is reserved on a worldwide basis to provide a common signalling channel (CSC) to the VHF digital link (VDL). This CSC uses the Mode 2 VDL modulation scheme and carrier sense multiple access (CSMA).

4.1.4    Auxiliary frequencies for search and rescue operations

4.1.4.1    Where a requirement is established for the use of a frequency auxiliary to 121.5 MHz, as described in 4.1.3.1.1 c), the frequency 123.1 MHz shall be used.

4.1.4.2    The auxiliary search and rescue channel (123.1 MHz) shall be available only with the characteristics as contained in Annex 10, Volume III, Part II, Chapter 2 for equipment with 25 kHz channel spacing.

4.1.5    Provisions concerning the deploymentof VHF frequencies and the avoidance of harmful interference

4.1.5.1    In the case of those VHF facilities providing service up to the radio horizon, tThe geographical separation between facilities operatingworking on the same frequency shall, except where there is an operational requirement for the use of common frequencies for groups of facilities, be such that points at the edge of the Designated Operational Coverage protection heights and at the limit of the functional service range of each facility are separated by distances not less than that required to provide a desired to undesired signal ratio of 2014 dB or by a separation distance not less than the sum of the distances from each point to the associated radio horizon (radio line-of-sight), whichever is smaller.

4.1.5.1.1 Recommendation This provision shall be implemented on the basis of a regional air navigation agreement. For areas where frequency assignment congestion is not severe or is not anticipated to become severe, the separation distance between facilities operating on the same frequency to provide a D/U ratio of a 1420 dB dB or by a separation distance not less than the required to provide a desired to undesired signal ratio of 14 dB or by a separation distance not less than sum of the distances from each point to the associated radio horizon (radio line-of-sight), whichever is smaller (10 to 1 distance ratio) separation criteria or radio line-of-sight (RLOS) separation criteria (whichever is smaller) may be used. This provision shall be implemented on the basis of a regional air navigation agreement.

Note.— Guidance material relating to the establishment of the minimum separation distance based on the desired to undesired signal protection ratio of 20 dB or 14 dB and radio line-of-sight is contained in Attachment A and the ICAO Handbook on radio frequency spectrum requirements for Civil Aviation, Volume II (Doc. 9718).

Note. – The application of the radio the minimum separation distance based on the sum of the distances to the associated radio horizon (radio line-of-sight) of each facility assumes that it is highly unlikely that two aircraft will be at the closest points between and at the maximum altitude of the associated Designated Operational Coverage of each facility.

1/11/01 4-18

Comment: 4.1.5.1 is not factual correct and confusing and should be re-organized to state the required protection to be achieved in frequency assignment planning. The statement of “VHF facilities providing service up to the radio horizon” limits the application on 4.1.5.1 and could be deleted. It is also proposed to revert back to the standard of a D/U ratio of 20 dB since this is applied in the majority of the Regions. Only Europe has agreed to use 14 dB. The use of 14 dB D/U ratio is proposed to be reverted into a Recommended Practice. The relevant D/U should be provided throughout the DOC (and not only at the point at the protection height and the limit of the functional service range). In case the separation distance to achieve the required D/U ratio is larger than the sum of the relevant distances to the radio horizon, the distance to the radio horizon should be used. The definition for DOC needs to be incorporated in Volume V.

Comment: Since Annex 10 Volume III contains SARPs for both 25 kHz and 8.33 kHz equipment, it is not clear if 4.1.3.2.2 refers to only 25 kHz characteristics or both 25 kHz and 8.33 kHz characteristics. This should be clarified.

Comment: This provision should be expanded with designating a CSC for VDL Mode 4.

4.1.5.2    In the case of those VHF facilities providing service beyond the radio horizon, except where there is an operational requirement for the use of common frequencies for groups of facilities, planning for co-channel operations shall be such that points at the protection heights and at the limits of the functional service area of each facility are separated by distances not less than the sum of distances from each point to its associated radio horizon.

Note 1.— The distance to the radio horizon from a station in an aircraft is normally given by the formula:

D = K √ h

where D = distance in nautical miles;h = height of the aircraft station above earth;K = (corresponding to an effective earth’s radius of 4/3 of the actual radius);

= 2.22 when h is expressed in metres; and= 1.23 when h is expressed in feet.

Note 2.— In calculating the radio line-of-sight distance between a ground station and an aircraft station, the distance from the radio horizon of the aircraft station computed from Note 1 must be added to the distance from the radio horizon of the ground station. In calculating the latter the same formula is employed, taking for h the height of the ground station transmitting antenna.

Note 3.— The criterion contained in 4.1.5.12 is applicable in establishing minimum geographical separation between VHF facilities, with the object of avoiding co-channel air-to-air interference. Guidance material relating to the establishment of separation distances between ground stations and between aircraft and ground stations for co-channel operations is contained in Section 3 of Attachment A and the ICAO Handbook on radio frequency spectrum requirements for Civil Aviation, Volume II (Doc. 9718). Guidance material relating to adjacent channel frequency deployment is contained in Section 2 of Attachment A.

Note 4.— Guidance material on the interpretation of 4.1.5.1 and 4.1.5.2 is contained in Attachment A.

4.1.5.3    The geographical separation between facilities operating working on adjacent channels shall be such that points at the edge of the Designated Operational Coverage protection heights and at the limit of the functional service range of each facility are separated by a distance sufficient to ensure operations free from harmful interference.

Note.— Guidance material covering separation distances and related system characteristics is contained in Attachment A and the ICAO Handbook on radio frequency spectrum requirements for Civil Aviation, Volume II (Doc. 9718).

4.1.5.4    The protection height shall be a height above a specified datum associated with a particular facility, such that below it harmful interference is improbable.

Comment: 4.1.5.2 is assumed to refer to extended range facilities using troposcatter propagation. Currently, extended range facilities are implemented using either landline or VSAT links to connect to the remote transmitter/receiver. The ground transmitters, operating on the same frequency, are configured as described in Annex 10 Volume III for off-set carrier or Climax systems. The protection requirements for these extended range facilities are as already described in 4.1.5.1.

Comment: Notes 1, 2 and 3 above should be moved, as amended, to Attachment A as it provides material to for the application of the SARPs in 4.1.5.1 and 4.1.5.1.1. The proposed changes are editorial.

4.1.5.5    The protection height to be applied to functions or to specific facilities shall be determined regionally, taking into consideration the following factors:

a) the nature of the service to be provided;

b) the air traffic pattern involved;

c) the distribution of communication traffic;

d) the availability of frequency channels in airborne equipment;

e) probable future developments.

4.1.5.6    Recommendation.— Where the Designated Operational Coverage protection heights determined are is less than those operationally desirable, separation between facilities operating on the same frequency should not be less than that necessary to ensure that an aircraft at the edge limit of the Designated Operational Coverage functional service range and the operationally desirable protection height of one facility does not come above the radio horizon with respect to adjacent facilities.

Note.— The effect of this recommendation is to establish a geographical separation distance below which harmful interference is probable.

4.1.5.7    The geographical separation between VHF VOLMET stations shall be determined regionally and, generally, shall be such that operations free from harmful interference are secured throughout the Designated Operational Coverage of each the VOLMET station at the highest altitude flown by aircraft in the area concerned.

Note.— Guidance material on the interpretation of 4.1.5.7 is contained in Attachment A and the ICAO Handbook on radio frequency spectrum requirements for Civil Aviation, Volume II (Doc. 9718).

4.1.5.8    Frequencies in the aeronautical mobile VHF band used for national services, unless worldwide or regionally allotted to this specific purpose, shall be so deployed that minimum interference is caused to facilities for the international air services in this band.

4.1.5.9    Recommendation.— The problem of inter-State interference on frequencies allotted worldwide or on a regional basis to national services, should be resolved by consultation between the administrations concerned.

4.1.5.10    The power communication coverage provided by a VHF ground transmitter shall, in order to avoid harmful interference to other stations, be kept to the minimum consistent with the operational requirement for the function.

1/11/01 4-20

Comment: With the inclusion of the definition for Designated Operational Coverage 4.1.5.4 and 4.1.5.5 are no longer required.

Comment: Frequency planning criteria are applied for national and international services (see 4.1.1.1) without discrimination between services in all Regions. Paragraphs 4.1.5.8 and 4.1.5.9 can be deleted.

Comment: It is assumed that this provision is to encourage the e.i.r.p of the VHF ground transmitter to be the minimum (i.e. to achgieve the minimum required field strength at the edge of coverage) to achieve the operational requirement (DO C) of the function.

Comment: The provision of 4.1.5.6 is confusing as, in the original text it refers to a protection height that is less than the functional service range/height. Paragraph 4.1.5.6 may be deleted.

Comment: Subject to harmonizing the geographical separation between VOLMET stations as proposed in the new Attachment A (paragraph 3.1.3.1 and 3.2.3.1, 4.1.5.7 may be deleted.

4.1.5.11    Recommendation.— For ground VHF facilities which provide service beyond the radio horizon, any spurious or harmonic radiation outside the band ±250 kHz from the assigned carrier frequency should not exceed an effective radiated power of 1 mW in any azimuth.

4.1.6    Equipment requirements

Note 1.— Frequency tolerances to which stations operating in the aeronautical mobile band (117.975 – 137  MHz) must conform are contained in Appendix 3 to the Radio Regulations. Tolerances for transmitters used for aeronautical services are not mentioned in this Annex, except in those cases where tighter tolerances than those contained in the Radio Regulations are required (e.g. the equipment specifications in Volume III contain several such instances).

Note 2.— The frequency tolerance applicable to individual components of a multi-carrier or similar system will be determined by the characteristics of the specific system.

4.1.6.1    Recommendation.— The antenna gain of an extended range VHF facility should preferably be such as to ensure that, beyond the limits of ±2Φ about the centre line of the angular width Φ of the area to be served, it does not exceed 3 dB above that of a dipole. But, in any case, it should be such as to ensure freedom from harmful interference with other radio services.

Note 1.— The actual azimuth, the angular width of the service area, and the effective radiated power would have to be taken into account in each individual case.

Note 2.— Guidance material on the interpretation of 4.1.6.1 is contained in Attachment A.

4.1.7    Method of operation

4.1.7.1    Single channel simplex operation shall be used in the VHF band 117.975 – 137 MHz at all stations providing service for aircraft engaged in international air navigation.

4.1.7.2    In addition to the above, the ground-to-air voice channel associated with an ICAO standard radio navigational aid may be used, subject to regional agreement, for broadcast or communication purposes or both.

4.1.8    Plan of assignable VHF radio frequenciesfor use in the international aeronautical mobile service

Comment: 4.1.5.11 is assumed to refer to extended range facilities based on troposcatter propagation. These are not used [anymore]. 4.1.5.11 can be deleted.

Comment: Equipment requirements, including frequency stability and unwanted or spurious emission levels for air/ground communication systems (voice and data) are contained in Annex 10, Volume III. Section 4.1.6 can be deleted

Comment: Paragraph 4.1.7.2 seems to be out of place and may be moved to Annex 10, Volume III.. The use of voice channels on VOR or NDB frequencies is provided for in Annex 10, Volume I and are out of place in this Chapter.

Comment: The plan for assignable VHF frequencies provides for grouping of frequencies based on 100 kHz channel spacing in the band 117.975 – 132 MHz (Group A), 50 kHz channel spacing in the band 117.975 – 132 MHz (Group B) and 50 kHz channel spacing in the band 132 – 137 MHz (Group C), 25 kHz channel spacing in the band 132 – 137 MHz (Group D) and 25 kHz channel spacing in the band 117.975 – 132 MHz (Group E) and finally 8.33 kHz channel spacing in the band 117.975 – 137 MHz (Group F). This grouping is based on the evolution of the use of the VHF band since 1945. It is proposed to delete the groupings and the provisions for selecting frequencies based on 50 kHz and 100 kHz channel spacing since the use of VHF frequencies in all Regions is based on either 25 kHz or 8.33 kHz channel spacing. The list of assignable frequencies (see 4.1.8.1.2 and the Appendix to Chapter 4) should be replaced with a list assignable frequencies for 25 kHz channel spacing and a list of assignable frequencies for 8.33 kHz channel spacing. The amendments to section 4.1.8 below are based on this proposal.

Introduction

This plan designates the list of frequencies available for assignment, together with provision for the use by the aeronautical mobile (R) service of all frequencies with a channel spacing of 25 kHz, and of all frequencies with a channel width and spacing of 8.33 kHz., with the frequencies in Group A continuing to be used wherever they provide a sufficient number to meet the operational requirements.

The plan provides that the total number of frequencies required in any region would be determined regionally. The effect of this will be that frequencies assignable in any particular region may be restricted to a limited number of the frequencies in the list, the actual number being selected as outlined herein.

In order that the assignable frequencies may be coordinated between regions as far as practicable, the plan requires that, whenever the number of frequencies contained in Group A of 4.1.8.1.2 is sufficient to meet the requirements of a region, the frequencies of this Group be used in a sequence commencing with 118 MHz. This ensures that all regions will have in common the frequencies used in the region requiring the least number of frequencies and, in respect to any two regions, the region with the greater number will have in use all the frequencies used by the other.

Group A provides for frequency planning based on 100 kHz channel spacing.

Group B of the list at 4.1.8.1.2 contains the frequencies in the band 117.975 – 132 MHz ending in 50 kHz. Together with the frequencies in Group A, they provide for frequency planning based on 50 kHz channel spacing. In Group C are listed the frequency channels in the band 132 – 137 MHz based upon 50 kHz channel spacing. Group D contains the frequency channels in the band 132 – 137 MHz ending in 25 kHz, and Group E similarly lists the frequency channels in the band 117.975 – 132 MHz. The utilization of channels in Groups B, C, D and E is explained below.

Group F of the list at 4.1.8.1.2 contains the frequencies in the band 117.975 – 137 MHz when 8.33 kHz channel width is used. The utilization of the channels in this Group is explained below.

Whenever the number of frequencies required in a particular region exceeds the number in Group A, frequencies may be selected from the other Groups taking into account the provisions of 4.1.8.1 with respect to the use of channels based on 25 kHz channel spacing and, with regard to the band 132 – 137 MHz, the provisions of the Radio Regulations (see Introduction to 4.1). Although for Groups B, C, D and E a preferred order of selection is not indicated, regional planning may require a particular selection of frequencies from these Groups in order to cater for specific regional circumstances. This may apply particularly to the utilization of frequencies from the band 132 – 137 MHz for reasons of available airborne equipment and/or availability of particular frequency channels for the aeronautical mobile (R) service. It may also be found that, in a particular region, it is desirable to select frequencies from Group B first, before selecting frequencies from Groups C, D or E.

Where all the channels of Groups A, B, C, D and E of the list at 4.1.8.1.2 are insufficient to meet the requirements of a region, a part or parts of the band may be designated as containing 8.33 kHz width channels or designated as supporting VDL Mode 3. For parts of the band containing 8.33 kHz width channels, the appropriate frequencies from Group F should be used in accordance with 4.1.8.1.1.1 and 4.1.8.1.2. It should be noted that the designation of frequencies in Group F differs from that of the corresponding frequencies in Groups A to E to emphasize the difference in channel width. For part of the bands supporting VDL Mode 3, frequencies from Groups A, B, C, D and E are utilized on a time-division basis. A single frequency supports multiple channels, each utilizing the frequency in periodic time frames or time slots. Specific time slots for VDL Mode 3 are identified using the numeric designators of Table 4-1 (bis).

1/11/01 4-22

Although for Group F a preferred order of selection is not indicated, regional planning may require a particular selection of frequencies from this group in order to cater for specific regional circumstances.

In many regions particular frequencies have already been allotted assigned for particular functions as, for instance, aerodrome or approach control. The plan does not make such allotmentsassignments (except as provided for in 4.1.1.1)in respect to the emergency channel and ground service frequencies), such action being taken regionally if considered desirable.

4.1.8.1    The frequencies in the band 117.975 – 137 MHz for use in the aeronautical mobile (R) service shall be selected from the lists in 4.1.8.1.2.

4.1.8.1.1    When the number of frequencies required in a particular region does not exceed the number of frequencies contained in Group A of 4.1.8.1.2, the frequencies to be used shall be selected in sequence, in so far as practicable, from those in Group A of 4.1.8.1.2.

4.1.8.1.1.1    When the number of frequencies required in a particular region exceeds those available in Groups A to E of 4.1.8.1.2, parts of the band shall be designated as containing 8.33 kHz width channels (voice) or as containing VDL Mode 3. Appropriate frequencies shall be selected from Group F of 4.1.8.1.2 for 8.33 kHz channel assignments or from Groups A to E in accordance with the time-slot assignments in accordance with Table 4-1 (bis) for VDL Mode 3. The remainder of the band shall continue to be used for 25 kHz width channels selected from the appropriate parts of Groups A to E.

Note 1.— The frequencies 121.425 – 121.575 MHz inclusive, 123.075 – 123.125 MHz inclusive and 136.500 – 136.975 MHz inclusive are not available for assignment to channels of less than 25 kHz width or VDL Mode 3.

Note 2.— Services that continue operation using 25 kHz assignments will be protected in regions implementing 8.33 kHz channel spacing.

4.1.8.1.2    List of assignable frequencies

The list of assignable frequencies is shown in the Appendix to this chapter.

4.1.8.1.2.1 List A contains the assignable frequencies in Regions or areas where 25 kHz frequency assignments are deployed

4.1.8.1.2.2 List B contains the assignable frequencies in Regions or areas where 8.33 kHz assignments are deployed.

4.1.8.1.3.3 For VDL Mode 3, frequency assignments are made in accordance with the provisions of 4.1.8.1.2 and the VDL Mode 3 time-slot assignments in accordance with Table 4-1 (bis).

Note: In Regions or areas frequency assignments from both List A abd List B can be used.

4.1.8.1.3    Recommendation.— Frequencies for operational control communications may be required to enable aircraft operating agencies to meet the obligations prescribed in Annex 6, Part I, in which case they should be selected from a dedicated the bands 128.825 – 132.025 MHz which is determined Regionally. These frequencies should be chosen, in so far as practicable, from the upper end of the band and in sequential order.

Note.— It is recognized that the assignment of such frequencies and the licensing of the operation of the related facilities are matters for national determination. However, in regions where a problem exists with respect to the provision of frequencies for operational control purposes, it may be advantageous if States endeavour to coordinate the requirements of aircraft operating agencies for such channels prior to regional meetings.

4.1.8.2    The frequencies that may be allotted for use in the aeronautical mobile (R) service in a particular region shall be

limited to the number determined as being necessary for operational needs in the region.

Note.— The number of frequencies required in a particular region is normally determined by the Council on the recommendations of Regional Air Navigation Meetings. The capabilities of VHF airborne equipment known to be widely used in the region will be taken into account in this determination.

1/11/01 4-24

APPENDIX TO CHAPTER 4.    LIST OF ASSIGNABLE FREQUENCIES

Frequency (MHz)

Annotations Frequency (MHz)

Annotations

121.5123.1121.60121.65121.70121.75121.80121.85121.90

Emergency frequencyAuxiliary frequency SAR

Reserved for aerodrome surfacecommunications[see Table 4-1, Item c)]

121.95121.625121.675121.725121.775121.825121.875121.925121.975

Reserved for aerodrome surfacecommunications[see Table 4-1, Item c)]

GROUP AFrequencies (MHz)

118.00118.10118.20118.30118.40118.50118.60118.70118.80

118.90119.00119.10119.20119.30119.40119.50119.60119.70

119.80119.90120.00120.10120.20120.30120.40120.50120.60

120.70120.80120.90121.00121.10121.20121.30121.40123.70

123.80123.90124.00124.10124.20124.30124.40124.50124.60

124.70124.80124.90125.00125.10125.20125.30125.40125.50

125.60125.70125.80125.90126.00126.10126.20126.30126.40

126.50126.60126.70126.80126.90127.00127.10127.20127.30

127.40127.50127.60127.70127.80127.90128.00128.10128.20

128.30128.40128.50128.60128.70128.80128.90129.00129.10

129.20129.30129.40129.50129.60130.90131.00131.10

131.20131.30131.40131.50131.60131.70131.80131.90

GROUP BFrequencies (MHz)

118.05118.15118.25118.35118.45118.55118.65118.75118.85

118.95119.05119.15119.25119.35119.45119.55119.65119.75

119.85119.95120.05120.15120.25120.35120.45120.55120.65

120.75120.85120.95121.05121.15121.25121.35123.75123.85

123.95124.05124.15124.25124.35124.45124.55124.65124.75

124.85124.95125.05125.15125.25125.35125.45125.55125.65

125.75125.85125.95126.05126.15126.25126.35126.45126.55

126.65126.75126.85126.95127.05127.15127.25127.35127.45

127.55127.65127.75127.85127.95128.05128.15128.25128.35

128.45128.55128.65128.75128.85128.95129.05129.15

129.25129.35129.45129.55129.65130.95131.05131.15

131.25131.35131.45131.55131.65131.75131.85131.95

GROUP CFrequencies (MHz)

132.00132.05132.10132.15132.20132.25132.30

132.35132.40132.45132.50132.55132.60132.65

132.70132.75132.80132.85132.90132.95133.00

133.05133.10133.15133.20133.25133.30133.35

133.40133.45133.50133.55133.60133.65133.70

133.75133.80133.85133.90133.95134.00134.05

134.10134.15134.20134.25134.30134.35134.40

134.45134.50134.55134.60134.65134.70134.75

134.80134.85134.90134.95135.00135.05

135.10135.15135.20135.25135.30135.35

135.40135.45135.50135.55135.60135.65

135.70135.75135.80135.85135.90135.95

GROUP DFrequencies (MHz)

132.025132.075132.125132.175132.225132.275132.325132.375132.425132.475

132.525132.575132.625132.675132.725132.775132.825132.875132.925132.975

133.025133.075133.125133.175133.225133.275133.325133.375133.425133.475

133.525133.575133.625133.675133.725133.775133.825133.875133.925133.975

134.025134.075134.125134.175134.225134.275134.325134.375134.425134.475

134.525134.575134.625134.675134.725134.775134.825134.875134.925134.975

135.025135.075135.125135.175135.225135.275135.325135.375135.425135.475

135.525135.575135.625135.675135.725135.775135.825135.875135.925135.975

136.000136.025136.050136.075136.100136.125136.150136.175136.200136.225

136.250136.275136.300136.325136.350136.375136.400136.425136.450136.475

136.500136.525136.550136.575136.600136.625136.650136.675136.700136.725

136.750136.775136.800136.825136.850136.875136.900136.925136.950136.975

GROUP EFrequencies (MHz)

118.025118.075118.125118.175118.225118.275118.325118.375118.425118.475118.525118.575118.625118.675118.725118.775118.825118.875

118.925118.975119.025119.075119.125119.175119.225119.275119.325119.375119.425119.475119.525119.575119.625119.675119.725119.775

119.825119.875119.925119.975120.025120.075120.125120.175120.225120.275120.325120.375120.425120.475120.525120.575120.625120.675

120.725120.775120.825120.875120.925120.975121.025121.075121.125121.175121.225121.275121.325121.375123.725123.775123.825123.875

123.925123.975124.025124.075124.125124.175124.225124.275124.325124.375124.425124.475124.525124.575124.625124.675124.725124.775

124.825124.875124.925124.975125.025125.075125.125125.175125.225125.275125.325125.375125.425125.475125.525125.575125.625125.675

125.725125.775125.825125.875125.925125.975126.025126.075126.125126.175126.225126.275126.325126.375126.425126.475126.525

126.575126.625126.675126.725126.775126.825126.875126.925126.975127.025127.075127.125127.175127.225127.275127.325127.375

127.425127.475127.525127.575127.625127.675127.725127.775127.825127.875127.925127.975128.025128.075128.125128.175128.225

128.275128.325128.375128.425128.475128.525128.575128.625128.675128.725128.775128.825128.875128.925128.975129.025129.075

129.125129.175129.225129.275129.325129.375129.425129.475129.525129.575129.625129.675130.925130.975131.025 131.075131.125

131.175131.225131.275131.325131.375131.425131.475131.525131.575131.625131.675131.725131.775131.825131.875131.925131.975

GROUP F(see also Table 4-1 (bis))

118.000 – 121.400 in 8.33 kHz steps 121.600 – 123.050 in 8.33 kHz steps 123.150 – 136.475 in 8.33 kHz steps

List A – assignable frequencies for 25 kHz channel spacing

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ANNEX 10 — VOLUME V 4-1 1/11/01

List A – 25 kHz channel spacing

118.000 118.025 118.050 118.075 118.100 118.125 118.150 118.175 118.200 118.225 118.250 118.275 118.300 118.325 118.350 118.375 118.400 118.425 118.450 118.475

118.500 118.525 118.550 118.575 118.600 118.625 118.650 118.675 118.700 118.725 118.750 118.775 118.800 118.825 118.850 118.875 118.900 118.925 118.950 118.975

119.000 119.025 119.050 119.075 119.100 119.125 119.150 119.175 119.200 119.225 119.250 119.275 119.300 119.325 119.350 119.375 119.400 119.425 119.450 119.475

119.500 119.525 119.550 119.575 119.600 119.625 119.650 119.675 119.700 119.725 119.750 119.775 119.800 119.825 119.850 119.875 119.900 119.925 119.950 119.975

120.000 120.025 120.050 120.075 120.100 120.125 120.150 120.175 120.200 120.225 120.250 120.275 120.300 120.325 120.350 120.375 120.400 120.425 120.450 120.475

120.500 120.525 120.550 120.575 120.600 120.625 120.650 120.675 120.700 120.725 120.750 120.775 120.800 120.825 120.850 120.875 120.900 120.925 120.950 120.975

121.000 121.025 121.050 121.075 121.100 121.125 121.150 121.175 121.200 121.225 121.250 121.275 121.300 121.325 121.350 121.375 121.400 121.425 121.450 121.475

121.500 121.525 121.550 121.575 121.600 121.625 121.650 121.675 121.700 121.725 121.750 121.775 121.800 121.825 121.850 121.875 121.900 121.925 121.950 121.975

122.000 122.025 122.050 122.075 122.100 122.125 122.150 122.175 122.200 122.225 122.250 122.275 122.300 122.325 122.350 122.375 122.400 122.425 122.450 122.475

122.500 122.525 122.550 122.575 122.600 122.625 122.650 122.675 122.700 122.725 122.750 122.775 122.800 122.825 122.850 122.875 122.900 122.925 122.950 122.975

123.000 123.025 123.050 123.075 123.100 123.125 123.150 123.175 123.200 123.225 123.250 123.275 123.300 123.325 123.350 123.375 123.400 123.425 123.450 123.475

123.500 123.525 123.550 123.575 123.600 123.625 123.650 123.675 123.700 123.725 123.750 123.775 123.800 123.825 123.850 123.875 123.900 123.925 123.950 123.975

124.000 124.025 124.050 124.075 124.100 124.125 124.150 124.175 124.200 124.225 124.250 124.275 124.300 124.325 124.350 124.375 124.400 124.425 124.450 124.475

124.500 124.525 124.550 124.575 124.600 124.625 124.650 124.675 124.700 124.725 124.750 124.775 124.800 124.825 124.850 124.875 124.900 124.925 124.950 124.975

125.000 125.025 125.050 125.075 125.100 125.125 125.150 125.175 125.200 125.225 125.250 125.275 125.300 125.325 125.350 125.375 125.400 125.425 125.450 125.475

125.500 125.525 125.550 125.575 125.600 125.625 125.650 125.675 125.700 125.725 125.750 125.775 125.800 125.825 125.850 125.875 125.900 125.925 125.950 125.975

126.000 126.025 126.050 126.075 126.100 126.125 126.150 126.175 126.200 126.225 126.250 126.275 126.300 126.325 126.350 126.375 126.400 126.425 126.450 126.475

126.500 126.525 126.550 126.575 126.600 126.625 126.650 126.675 126.700 126.725 126.750 126.775 126.800 126.825 126.850 126.875 126.900 126.925 126.950 126.975

127.000 127.025 127.050 127.075 127.100 127.125 127.150 127.175 127.200 127.225 127.250 127.275 127.300 127.325 127.350 127.375 127.400 127.425 127.450 127.475

127.500 127.525 127.550 127.575 127.600 127.625 127.650 127.675 127.700 127.725 127.750 127.775 127.800 127.825 127.850 127.875 127.900 127.925 127.950 127.975

128.000 128.025 128.050 128.075 128.100 128.125 128.150 128.175 128.200 128.225 128.250 128.275 128.300 128.325 128.350 128.375 128.400 128.425 128.450 128.475

128.500 128.525 128.550 128.575 128.600 128.625 128.650 128.675 128.700 128.725 128.750 128.775 128.800 128.825 128.850 128.875 128.900 128.925 128.950 128.975

129.000 129.025 129.050 129.075 129.100 129.125 129.150 129.175 129.200 129.225 129.250 129.275 129.300 129.325 129.350 129.375 129.400 129.425 129.450 129.475

129.500 129.525 129.550 129.575 129.600 129.625 129.650 129.675 129.700 129.725 129.750 129.775 129.800 129.825 129.850 129.875 129.900 129.925 129.950 129.975

130.000 130.025 130.050 130.075 130.100 130.125 130.150 130.175 130.200 130.225 130.250 130.275 130.300 130.325 130.350 130.375 130.400 130.425 130.450 130.475

130.500 130.525 130.550 130.575 130.600 130.625 130.650 130.675 130.700 130.725 130.750 130.775 130.800 130.825 130.850 130.875 130.900 130.925 130.950 130.975

131.000 131.025 131.050 131.075 131.100 131.125 131.150 131.175 131.200 131.225 131.250 131.275 131.300 131.325 131.350 131.375 131.400 131.425 131.450 131.475

131.500 131.525 131.550 131.575 131.600 131.625 131.650 131.675 131.700 131.725 131.750 131.775 131.800 131.825 131.850 131.875 131.900 131.925 131.950 131.975

132.000 132.025 132.050 132.075 132.100 132.125 132.150 132.175 132.200 132.225 132.250 132.275 132.300 132.325 132.350 132.375 132.400 132.425 132.450 132.475

132.500 132.525 132.550 132.575 132.600 132.625 132.650 132.675 132.700 132.725 132.750 132.775 132.800 132.825 132.850 132.875 132.900 132.925 132.950 132.975

133.000 133.025 133.050 133.075 133.100 133.125 133.150 133.175 133.200 133.225 133.250 133.275 133.300 133.325 133.350 133.375 133.400 133.425 133.450 133.475

133.500 133.525 133.550 133.575 133.600 133.625 133.650 133.675 133.700 133.725 133.750 133.775 133.800 133.825 133.850 133.875 133.900 133.925 133.950 133.975

134.000 134.025 134.050 134.075 134.100 134.125 134.150 134.175 134.200 134.225 134.250 134.275 134.300 134.325 134.350 134.375 134.400 134.425 134.450 134.475

134.500 134.525 134.550 134.575 134.600 134.625 134.650 134.675 134.700 134.725 134.750 134.775 134.800 134.825 134.850 134.875 134.900 134.925 134.950 134.975

135.000 135.025 135.050 135.075 135.100 135.125 135.150 135.175 135.200 135.225 135.250 135.275 135.300 135.325 135.350 135.375 135.400 135.425 135.450 135.475

135.500 135.525 135.550 135.575 135.600 135.625 135.650 135.675 135.700 135.725 135.750 135.775 135.800 135.825 135.850 135.875 135.900 135.925 135.950 135.975

136.000 136.025 136.050 136.075 136.100 136.125 136.150 136.175 136.200 136.225 136.250 136.275 136.300 136.325 136.350 136.375 136.400 136.425 136.450 136.475

136.500 136.525 136.550 136.575 136.600 136.625 136.650 136.675 136.700 136.725 136.750 136.775 136.800 136.825 136.850 136.875 136.900 136.925 136.950 136.975

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List B 8.33 kHz channel spacing.

118.000 – 121.400 in 8.33 kHz steps 121.600 – 123.050 in 8.33 kHz steps 123.150 – 136.475 in 8.33 kHz steps

Note: in the bands between 121.400 – 121.600 MHz, 123.050 – 123.150 MHz and 136.457 – 137 MHz frequency assignments with 8.33 kHz channel spacing are not permitted

______________________

ANNEX 10 — VOLUME V 4-1 1/11/01

ATTACHMENT A.    CONSIDERATIONS AFFECTING THE DEPLOYMENT OF VHF COMMUNICATION FREQUENCIES

1. Introduction

1.1 The frequency assignment planning criteria below are developed based on Annex 10, Volume V, Chapter 4, paragraphs 4.1.5.1 and 4.1.5.1.1 A, as well as material in Annex 10, Volume III, Part II, 2.1, 2,2 and 2.3.

1.2 This attachment contains the technical aspects related to the development of frequency assignment planning criteria for VHF air/ground communication systems and provides the methodology to calculate geographical separation distances between VHF air/ground communication facilities. Regional differences can be accommodated, where justified and necessary. Regional differences are to be incorporated in the relevant Regional Air Navigation Plans.

2. Frequency assignment planning criteria.

2.1 The following technical characteristics apply to frequency assignment planning for VHF air/ground communications systems:

a. The desired to undesired signal protection ratio D/U is 20 dB (Some Regions, [like the EUR Region] apply 14 dB)Reference: Annex 10, Volume V, Chapter 4, §4.1.5.1

b. Minimum field strength at the airborne receiver: 75 µV/m (-82 dBm)Reference Annex 10, Volume III, § 2.2.1.2, RecommendationMinimum field strength air the ground receiver: 20 µV/m (-93 dBm)Reference: Annex 10, Volume III, § 2.3.1.2

c. Adjacent Channel rejection: 60 dBd. Channel spacing: 25 kHz; 8.33 kHz in Regions where agreed by Regional Air

Navigation AgreementReference: Annex 10, Volume V, Chapter 4, §4.1.2.2

2.2 Separation distances

Co-frequency (D/U is 20 dB): The separation distance between the Designated Operational Coverage (DOC)1 areas of two facilities operating on the same frequency shall be greater than the sum of the

1 ? Designated operational range or height (DOR or DOH) – The range or height to which an aid is needed operationally in order to provide a particular service and within which the facility is afforded frequency protection.

Note 1 – The designated value for range or height is determined in accordance with the criteria for the deployment of the aid in question.Note 2 – The designated value for range or height forms the basis for the technical planning of aids.

(39 pages) document.doc

Comment: Consideration could be given to upgrade the Recommendation in Annex 10, Volume III, Part II, paragraph 2.2.1.2 to a Standard.

Comment: Replacement of the current Attachment A with the material below is proposed

distances to the radio horizon for each facility (Radio Line-Of-Sigh (RLOS)). Reference: Annex 10, Volume V, Chapter 4 §4.1.5.1

Note: In [almost] all cases where 20 dB D/U protection is applied, the minimal geographical separation distance between facilities, in accordance with the provisions of 4.1.5.1,is determined by the sum of the distances to the radio horizon from the edge of the DOC (at maximum Designated Operational Range and maximum Designated Operational Height) of each facility.

Co-frequency (D/U is 14 dB): The separation distance between the Designated Operational Coverage (DOC) areas of two facilities operating on the same frequency shall be greater than required to provide a D/U ratio of 14 dB or the the sum of the distances to the radio horizon for each facility (Radio Line-Of-Sigh (RLOS)). Reference Annex 10, Volume V, Chapter 4, § 4.1.5.1.1.

Note: In a number of cases where 14 dB D/U protection is applied, the separation distance to achieve the required protection is less than the Radio Line-Of-Sight criterion.

Adjacent frequency: The separation distance shall be sufficient to avoid harmful interference

Reference: Annex 10, Volume V, Chapter 4, § 4.1.5.3

2.3 Calculation of the distance to the radio horizon (radio line-of-sight).

2.3.1 The distance to the radio horizon can be calculated with the formula: D = K √ h (1) where

D = distance in NMK = 1.23 (corresponding to an effective Earth radius of 4/3 or the actual radius)h = height above Earth (feet)

2.4 Propagation model: RF-propagation is, for the purpose of frequency assignment planning, based on free space propagation.

3. Geographical separation distances

Note: For more details on establishing geographical separation distances, see the ICAO Handbook on Radio Frequency Spectrum Requirements for Civil Aviation (Doc. 9718), section 2.7.

3.1 Co-frequency separation

Note: The criteria in this section used to calculate minimum co-frequency separation distances apply to co-frequency operation of equipment with 25 kHz channel characteristics and 8.33 kHz characteristics. In areas where both equipment with 25 kHz and 8.33 kHz characteristics areas deployed, these criteria also

Designated operational coverage (DOC) – The combination of the designated operational range and the designated operational height (e.g. 200NM/FL500 is the designated operational coverage for an aid with a designated operational range of 500 NM and a designated operational height of 50.000 ft (Flight Level 500).

(39 pages) document.doc

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apply between a 25 kHz channel and an 8,33 kHz channel that are separated by 8.33 kHz. (See also section 4 of this Attachement)

3.1.1 Air/ground communications

Figure A-1 Separation distances based on Radio Line-Of-Sight

3.1.1.1 The geographical separation between the ground facilities (see also Figure A-1) in cases where the Radio Line-Of-Sight criterion is applied can be calculated with the formula

where (2)

D = distance between ground station for facility A and facility BRA = DOR facility ARHA = distance to the radio horizon from the DOH of facility ARHB = distance to the radio horizon from the DOH of facility BRB = DOR facility BThe distance to the radio horizon is calculated with formula (1)

Note 1: All distances in NM.Note 2: This method of calculating separation distances does not in all cases provide a protection ratio D/U of 20 dB for the desired signal and takes into account that it is highly unlikely that two aircraft will be at the maximum edge of their respective DOC areas and at the closest point between the DOC areas simultaneously. However, when using a more realistic propagation model (e.g. the two ray propagation model) and using the actual antenna diagram of both ground based and aircraft transmitters, normally this method provides for the required protection.

3.1.1.2 In areas where the protection ratio has been agreed to be 14 dB (e.g. in the EUR Region) the geographical separation (see also figure A-2between the ground facilities can be calculated with the formulas

or (3)

(See 3.1.1.1 for a clarification of the symbols)

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Figure A-2 Separation distance based on the 14 dB D/U protection ratio.

The larger value of DA or DB determines the minimum geographical separation between the ground facilities. In cases where 5RA or 5RB is larger than the sum of the distances to the radio horizon of each facility, the geographical separation as in formula (2) applies.

Note: The separation distance calculated in accordance with formula (3) assumes that all transmitting stations have equal e.i.r.p. (typical 25 W). If the actual e.i.r.p differs, relevant adjustments to the use of this formula should be made.

3.1.1.3 These formulas are to be applied globally to establish the minimum geographical separation between ground facilities.

3.1.2 Air/ground communications and broadcast (VOLMET, ATIS)

3.1.2.1 When air/ground/air communication systems and aeronautical broadcast systems (VOLMET, ATIS) use the same frequency, the geographical separation between the ground facilities should be based on the distance that can be calculated as provided in § 3.1.1 [or 3.1.2, as required].

Note: This separation is necessary to avoid harmful interference from aircraft transmissions into the (desired) broadcast signals. See also RFPC WP/01 §2.7.3.1.4. Calculation of interference from the broadcast station can be calculated as provided in § 3.1.3 below.

3.1.3 Broadcast (VOLMET, ATIS)

3.1.3.1 In case two ground based aeronautical broadcast stations operate on the same frequency, the minimum geographical separation distance between the broadcast stations can be calculated as shown in Figure A-3 with formulas 4A and 4B. The largest value of the separation distance should be used.

Figure A-3 Interference between VHF aeronautical ground-based broadcast facilities

(interference from station B) (4A) or

(interference from station A (4B)

where

D = distance between ground station for facility A and facility BRA = DOR facility (broadcast station) A

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RHA = distance to the radio horizon from the DOH of facility (broadcast station) ARHB = distance to the radio horizon of the (ground) broadcast station B. For broadcast station B an antenna height of 65 feet is assumed, for which RHB = 9.9 NM

The minimum geographical separation distance is the largest value of the distance calculated with folrmulas 5A and 5B

(5A)

(5B)

3.2 Adjacent frequency separation

Note: The criteria used in this section to calculate minimum separation distances refer to the first adjacent 25 kHz or 8.33 kHz channel. In areas where both 25 kHz and 8.33 kHz channel spacing is deployed, protection of frequency assignments from harmful interference is to be established on the basis of the material in section 4 of this Attachment.

3.2.1 Air-ground communications

3.2.1.1 Calculation of the adjacent frequency separation distances assumes an adjacent (25 kHz) channel rejection of 60 dB. The worst case of interference is when two aircraft are operating nearby on the first adjacent frequency.

PD = 75 µV/m which corresponds to -82 dBm

Assuming that the interfering aircraft transmitter B has the following characteristics:P = 25 W (44dBm), cable losses -3 dB, antenna gain 0 dB, the unwanted (interfering) signal level at the (desired) aircraft receiver is (4)

or -19 -Lbf

D/U = PD – PU = -82 -41+Lbf + 60 = -63 + Lbf

Lbf = 79.88 + 20logd gives: D/U = -63 + 79.88 +20logd = 2020logd = 20 – 79.88 + 60 = 0.12Log d = 0.0006; D = 1 NM

To keep the undesired signal below the muting level of 5 µV/m (-105.3 dBm), the minimum separation distance between the desired and the undesired aircraft station can be calculated as follows: PU = -105.3 = +41 – LBF – 60 = -19 - LBF which gives LBF = 86.3 dB LBF = 79.88 + 20logd which gives 20logd = 6.42 logd = 0.321 d = 2.0 NM

5

Comment.: In the EUR Region a distance of 10 NM beyond the radio horizon is used. Annex 10 indicates in the guidance material that a distance of 30 NM beyond the radio horizon should be necessary. Actually, the required separation distance would depend on the DOC of the desired broadcast station. Not in all cases this criterion provides 20 dB protection when an aircraft is operating at the maximum range and height of the DOC of the broadcast facility.

ACP WG-W/4 AI-1

Note: Annex 10 indicates in the guidance material that a minimum separation distance of 3 NM should be maintained. All ICAO Regions however, are using a minimum adjacent frequency separation (25 kHz) distance of 10 NM.

The above figures would require the DOC areas for two facilities operating on the (first) adjacent (25 kHz) frequency to be separated by at least [2] [3] [10 ]NM)

Figure A-4 Adjacent frequency separation for air-ground services

The minimum geographical separation (see also figure A-4)between the ground stations is

D = RA +10 + RB (5)RA = DOR of broadcast facility ARB = DOR of broadcast facility B

Note: This separation distance also applies when one of the two services is a ground based aeronautical broadcast service.

3.2.2. Air-ground communications and broadcast (VOLMET, ATIS)

In order to protect the (desired) VOLMET receiver from interference from aircraft transmitters operating on the first adjacent (25 kHz) frequency, the separation criteria in 3.2.1 apply. To protect the desired aircraft receiver from interference from an undesired VOLMET ground station, the criteria in 3.2.3 apply

3.2.3 Broadcast (VOLMET, ATIS)

3.2.3.1 To protect an aircraft receiver from broadcast transmissions from a (ground) broadcast transmitter operating on the first adjacent (25 kHz) frequency below the 5 µV/m muting level, to separation between the aircraft receiver and the (undesired) broadcast transmitter the separation distance can be calculated along the same principles as contained in § 3.2.1 and, for a 25 W ground broadcast (undesired) transmitter, the same separation distance (between the aircraft transmitter and the broadcast ground station) would apply .

In case the e.i.r.p. of the unwanted broadcast station is increased to 100 W (50 dBm) , the separation distance as calculated in 3.2.1 would increase from 2 NM to 4 NM.

In principle, keeping the separation distance between an aircraft broadcast receiver from interference from another broadcast transmitter operating on the first (25 kHz) adjacent frequency would provide protection to below the 5µV/m muting level.

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Figure A-5 Geographical separation between the ground stations of two broadcast services operating on the first adjacent frequency.

The minimum geographical separation (see Figure A-5) between two ground broadcast transmitters operating on the first adjacent (25 kHz) adjacent frequency would become the larger value of :

D = RA + 13 NM (6A) or

D = RB + 13 NM

RA is the DOC for the (desired) broadcast service.

This protects both the VOLMET aircraft receiver as well as the air/ground communications aircraft receiver to an interfering signal level of the undesired broadcast facility to below the 5 µV/m muting level.

4. Use of 8.33 kHz and 25 kHz equipment in the same region or area.Note: Additional information on the use of 8.33 kHz and 25 kHz channels is in the Handbook on Radio Frequency Spectrum Requirements for Civil Aviation, Part II, DOC. 9718.

4.1     Where it is necessary to take account on a regional basis of receivers not specifically designed for an 8.33 kHz environment, the following characteristics should be assumed:

a) an 8.33 kHz channel, which is assigned 8.33 kHz away from the assigned frequency of a 25 kHz channel, is assumed to be co-channel with that 25 kHz channel;

b) an 8.33 kHz channel, spaced ±16.67 kHz from the assigned frequency of a 25 kHz channel is assumed under all operating conditions (including all instabilities and doppler shifts), to have an adjacent channel rejection ratio of:

i) 23 dB aircraft against ground offset carrier systems;

ii) 30 dB aircraft against ground non-offset carrier systems; and

iii) 27 dB aircraft against aircraft systems.

Worst case conditions for planning purposes are used here for a mixed environment of 8.33 kHz and 25 kHz systems.

c) an 8.33 kHz channel which is assigned 25 kHz away from the assigned frequency of a 25 kHz channel is assumed to have an effective adjacent channel characteristic of at least 60 dB.

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Comment: The material below is taken from the original Attachment A, paragraphs 2.5.1 and 2.5.2

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4.2 Where it is necessary to take account of the implementation of VHF stations which use 8.33 kHz channel spacing, in a region where 25 kHz assignments occur, the assumptions of 2.5.1 a) to c) result in the following:

a) where 8.33 kHz services are spaced ±8.33 kHz away from the assigned frequency of a 25 kHz channel, the regionally agreed planning criteria for co-channel assignments should be used, applying either the radio horizon method (assumed to give at least 20 dB D/U) or a desired-to-undesired signal ratio of 14 dB;

b) where 8.33 kHz services are spaced ±16.67 kHz away from the assigned frequency of a 25 kHz channel, the following criteria should be applied:

i) Receiver mute lift criteria.

The minimum separation distance required for the prevention of receiver mute lifts is:

187 NM aircraft against ground offset carrier systems;84 NM aircraft against ground non-offset carrier systems; and

118 NM aircraft against aircraft systems.

ii) Desired-to-undesired signal ratio.

The minimum distance required to provide sufficient adjacent channel protection based upon a D/U ratio (assuming equal ERP from the wanted and unwanted signals) can be calculated given the maximum service range of the wanted signal by:

Dadj = service range/(10 (ACR – D/U)/20)

Dadj = distance required between the edges of the two service ranges operating on adjacent channels

ACR = adjacent channel rejection

Dadj and service range expressed in the same units.

The D/U ratio used will depend on regionally agreed planning criteria.

Note.— The application of the 14 dB planning criteria assumes that it is highly unlikely that two aircraft will be at the maximum edge of their respective service volumes and at the closest point between these two volumes.

c) 8.33 kHz channels spaced 25 kHz away from an assigned frequency of a 25 kHz channel should be planned in accordance with 2.2.

5. VDL Mode 2 and VDL Mode 45.1 Co-channel operation For VDL systems operating on the same frequency as VHF voice systems or between different VDL (Mode 2 and Mode 4) systems, the minimum geographical separation distance can be calculated using the frequency assignment planning criteria and methodology as in section 2 and 3.1 above. 5.2 Adjacent channel operation

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5.2.1 Within the same airspace, the first adjacent (25 kHz) channel to a VDL Mode 4 station should not be used for a frequency assignment to a 25 kHz VHF voice channel. A guard band of 25 kHz should be observed when using 8.33 kHz adjacent channels.

5.2.2 Within the same airspace, the first and second adjacent (25 kHz) channel to a VDL Mode 4 station should not be used for a frequency assignment to a 25 kHz VHF voice channel. A guard band of 50 kHz should be observed when using 8.33 kHz adjacent channels.5.2.3. Within the same airspace, a guard band of 25 kHz should be used between different VDM (Mode 2 and Mode 4 system)

5.2.4 Attention is drawn to the possibility of interference between DSB-AM and VDL Mode 2/4 when these systems are used on the surface of an airport. Interference can occur if the frequency separation (guard band) is four channels (25 kHz) or less. In this case interference between aircraft stations can be prevented through securing that the minimum field strength of these systems is 70 dBm at the antenna. Any interference that may be caused in ground based receiving stations (i.e. not aircraft stations) can be mitigated through using cavity filters that block in these receivers the reception of unwanted signals from transmissions from aircraft operating on the surface of an airport.

9

Comment. It is assumed that the interference that can be caused by VDL on the first adjacent 25 kHz VHF voice channel applies to the 8.33 kHz channels in the same frequency range. No compatibility tests assessing interference from VDL (Mode 2 or Mode 4) into equipment designed for 8.33 kHz channel spacing has been undertaken.