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Commentary - Electronic identification
    [p.1247] Annex I, Article 8 -- Electronic identification


    [p.1248] General remarks

    4195 The use of radar to identify medical aircraft was discussed at the meeting of technical experts held at the ICRC in 1970. Two identification systems were studied:

    -- the secondary surveillance radar (SSR) system used by international civil aviation;
    -- the radar identification echo transmission system put forward by the International Electrotechnical Commission (IEC).

    4196 The experts recommended the secondary radar system, which is more and more commonly used worldwide and is less costly than the identification echo transmission system, although the latter has a number of other advantages.

    4197 The Technical Sub-Commission of the 1972 Conference of Government Experts also proposed the use of the secondary surveillance radar (SSR) system; Annex I, Article 11, of the 1973 ICRC draft is entitled "Secondary surveillance radar (SSR) system signal". (1)

    4198 At the first session of the Diplomatic Conference, Article 11 was replaced by Article 9, "Secondary radar identification such as IFF/SIF", as a result of the work of the Technical Sub-Committee which added the initials IFF/SIF to the title of Article 9 in order to make it more specific. The meaning is:

    IFF = Identification Friend or Foe
    SIF = Selective Identification features.

    4199 The ICAO representative pointed out that these initials were military and could not be applied to civil aviation. (2)

    4200 After revision by the Technical Sub-Committee in 1976, Article 9 became Article 8 , "Electronic identification", with its present text. Article 9 called for codes set aside for the exclusive use of medical aircraft, a requirement which could not be met in either 1974 or 1976 under the secondary surveillance radar (SSR) system. At the third session of the Conference, the Technical Sub-Committee avoided further lengthy discussion on the matter by dropping the p.1249] requirement for exclusive radar codes, replacing the reference to secondary radar in the title by the word "electronic" and deleting the military initials IFF/SIF.

    4201 Nonetheless, it is with the SSR system and its modes and codes that Article 8 is concerned stipulating that the procedures for obtaining modes and codes for the exclusive use of medical aircraft are to be recommended by ICAO.

    4202 To this end, Resolution 17 addressed by the Diplomatic Conference to ICAO invites the latter to "establish appropriate procedures for the designation, in case of an international armed conflict, of an exclusive SSR mode and code to be employed by medical aircraft concerned". (3)

    4203 Secondary surveillance radar was developed from the IFF military system used during the Second World War to locate aircraft and ships. The IFF system consists of a primary, interrogator or surveillance radar and a transponder installed on board the aircraft or ship, enabling the latter to be identified when detected by the primary radar. The transponder is the system's secondary radar.

    4204 The primary radar, installed on land or on board ship, sweeps the horizon with an electromagnetic pulse stream. When the pulses encounter a "target" -- aircraft or ship -- an echo is sent back, producing a luminous dot on the primary radar's display screen and enabling the detected target to be located. At the same time the primary radar's pulses trigger the target's transponder, which automatically starts to transmit the allocated identification code at which it has been set. A decoding device connected to the primary radar display reproduces the identification code alongside the luminous dot representing the target.

    4205 The mode of an IFF or secondary radar system gives the characteristics of the interrogation pulses: amplitude, duration, interval etc. The identification code consists of four digits. Aircraft are identified by means of military SSR modes numbered from 1 to 4 and civilian modes A, B, C and D defined by ICAO. (4)

    4206 Modes A and 3 are common to civilian and military operations, as is mode C which is used to determine aircraft altitude. Modes A, 3 and C are used for air traffic control.

    4207 Like the modes, the identification codes are limited in number, so that a code cannot be set aside for the exclusive use of medical aircraft, of which there are relatively few; nevertheless, the matter is still under study by ICAO, which holds the view that the chances of being able to select an exclusive radar code for medical aircraft probably depend on the development of secondary radar modes with greater data processing capacity than the above-mentioned existing ones. At the present time, ICAO is in charge of the procedure for allocating secondary radar codes (Annex 10, Aeronautical Telecommunications, Vol. I, Part I, para. 2.5.4.1).

    4208 National administrations responsible for air navigation control, in particular air traffic services (ATS), are invited to draw up procedures for the allocation of [p.1250] radar codes on a regional basis, in accordance with ICAO. In allocating the codes, account should be taken of regional air navigation arrangements.

    4209 Radar codes have on occasion been allocated to medical aircraft by arrangement between the Parties to a conflict. In one case, the codes 5000 and 5100 were allocated, respectively, by each of the Parties to the conflict to its own medical aircraft.

    4210 Under Chapter XIV of the International Code of Signals, the group YYY is used as the distinctive signal for transponders on board hospital ships. In radiotelegraphy, this group is also used as a prefix in the radiocommunications of medical units and transports, pursuant to Article 40, Section II, of the Radio Regulations.

    Paragraph 1

    4211 In international civil aviation the same frequencies are used worldwide for secondary radar pulses:

    -- 1030 MHz for interrogation transmissions;
    -- 1090 MHz for the reply transmission from the transponder. (5)

    4212 These frequencies are used by civilian aircraft all over the world and to a large extent by military aircraft as well. Some air forces are said to use other frequencies, probably in the band between 700 MHz and 1040 MHz. Since the frequencies used are known, compatible equipment allowing the radar identification code to be displayed on the interrogator screen can be defined. Radar identification of a medical aircraft should therefore give rise to no difficulty wherever military or civilian SSR facilities exist.

    4213 At the 1972 Conference of Government Experts, this principle was accepted by the Technical Sub-Commission which recommended, for the secondary radar mode and code:

    -- Mode 3/A;
    -- Code: to be agreed upon or specified by the Parties. (6)

    4214 This procedure is geared to the existing possibilities described by ICAO and outlined in the introduction to this Chapter.

    4215 The Parties to the conflict should endeavour to prevail upon their national air traffic services (ATS) to allocate a secondary radar identification code for use by their own medical aircraft in the aeronautical region affected by the conflict. This code, together with mode 3/A and the stated intention to use the distinctive signals, should immediately be notified to the other Party; the States not Parties to the conflict (hereinafter called "neutral States") should also be informed.

    [p.1251] Paragraph 2

    4216 IFF (friend or foe) identification systems have been designed to meet all the identification requirements of friendly land vehicles operating on the battlefield. The possibilities they offer include the following:

    -- ground-to-ground identification of friendly vehicles;
    -- compatibility with the existing ground-to-air system, enabling helicopters and aircraft operating above the battlefield to be identified;
    -- location of friends;
    -- search for a specific vehicle by means of its code.

    4217 These equipments operate on frequencies between 1030 MHz and 1090 MHz, which have already been mentioned in connection with the transponders on board aircraft in the secondary radar systems.

    4218 If the Parties to the conflict wish to use such radar identification systems for their medical units and transports on land, they should state their intention of doing so and notify each other of the radar codes and modes concerned. The agreement they conclude in this connection should specifically mention the region covered, in which exclusive use will be made of the radar identification code allocated to medical units and transport or in other words, land vehicles, ambulances and medical aircraft. This information should also be communicated to the neutral States.

    4219 At sea, only warships use IFF systems at the present time. The use of radar to identify hospital ships and other vessels (for example, rescue craft) protected by the Conventions and the Protocol would mean that appropriate frequencies, modes and codes would have to be established. International standards governing the use of electromagnetic frequencies for radar identification and tracking in the maritime mobile service are being studied by both the ITU and IMO. The use of shipborne transponders in a secondary radar system for the identification and tracking of civilian vessels is intended to enhance the safety of navigation at sea. The use of radar systems to monitor congested or dangerous areas and the entry to some harbours has paved the way for the studies which are currently being conducted on the standardization of civilian shipborne transponders. To this end, WARC-79 adopted Resolution No. 600 and Recommendation No. 605, relating respectively to the use of frequency bands by, and the technical characteristics of, shipborne transponders.

    4220 Resolution No. 600 and Recommendation No. 605, together with Recommendation No. 713 (Mob-83) relating to the use of radar transponders for facilitating research and rescue operations at sea are reproduced infra, pp. 1252-1255. The action taken with regard to these three texts will be of crucial importance for the ships and craft protected by the Geneva Conventions and Protocol. These issues are to be discussed at the WARC for the mobile services to be held in 1987.

    4221 The conclusion of the special agreement regarding the use of radar to identify medical ships and craft for which provision is made in paragraph 2 of this article will be facilitated once the related standards and international rules currently under study in the ITU and IMO have been adopted; the agreement in question should also cover life-saving appliances occupied by shipwrecked persons.

    ' Ph. E. '


    [p.1252] Documents annexed

    Document No. 1 (cf. supra, p. 1251)

    INTERNATIONAL TELECOMMUNICATION UNION

    RADIO REGULATIONS

    Edition of 1982 Revised in 1985 (Extract)

    RESOLUTION No. 600

    Relating to the Use for the Radionavigation Service of the Frequency Bands 2 900 - 3 100 MHz, 5 470 - 5 650 MHz, 9 200 - 9300 MHz, 9 300 - 9 500 MHz and 9 500 - 9 800 MHz

    The World Administrative Radio Conference, Geneva, 1979,

    ' considering '

    a) that this Conference has adopted provisions relating to the development of shipborne transponders in the maritime radionavigation service in frequency bands 2 930 - 2 950 MHz, 5 470 - 5 480 MHz and 9 280 280 - 9 300 MHz;

    b) the growing demands already being made on the frequency allocations for the radionavigation service in the bands utilized for aeronautical and maritime radionavigation arising from:

    i) the increasing number of shipborne radars which is reinforced by the demands being made for compulsory installation on an international basis;

    ii) the increasing need for navigational aids and transponders working with primary radars;

    iii) the need for the increasing utilization of this band by stations in the aeronautical radionavigation service noting that compulsory installation on board aircraft is also demanded on an international basis;

    c) the increase in harmful interference occurring in the 9 300 - 9 500 MHz band due to these factors;

    d) that these radar applications have important safety considerations;

    ' noting '

    a) Recommendation 605;

    b) the conclusions of the Special Preparatory Meeting of the CCIR;

    [p.1253] c) the need for additional operational and technical information in deciding the most effective frequency utilization;

    ' resolves '

    1. that the next competent world administrative radio conference shall:

    1.1. review footnotes to these radionavigation bands and make such changes as deemed appropriate in the light of additional studies;

    1.2 prepare regulatory recommendations as appropriate;

    2. that the CCIR shall continue to consider the technical factors and make Recommendations;

    ' invites '

    1. ' the Administrative Council ' to ensure that radionavigation matters of concern to the mobile services are included in the agenda of the next competent mobile conference;

    2. ' administrations ' to study the use of these bands by the radionavigation services and to submit proposals for their efficient utilization;

    ' requests the Secretary-General '

    to refer this Resolution to the IMCO and ICAO inviting their urgent consideration of the operational requirements for the maritime and aeronautical radionavigation services using these frequency bands, and to make appropriate recommendations to assist administrations in their preparation for the conference.


    Document No. 2 (' cf. supra, ' p. 1251)

    RECOMMENDATION No. 605

    Relating to Technical Characteristics and Frequencies
    for Shipborne Transponders (7), (8)

    The World Administrative Radio Conference, Geneva, 1979,

    ' considering '

    a) that merchant ships of the world are increasing in size and speed;

    b) that every year a significant number of collisions occur involving merchant vessels with resultant loss of life and property and that collisions have a high potential for endangering the natural environment;

    [p.1254] c) that there is a need to correlate radar targets with vessels making VHF radiotelephone transmissions;

    d) that studies and experiments have shown that shipborne transponders can enhance and supplement radar target images as compared with normal radar images;

    e) that current studies and experimentation relating to shipborne transponders indicate that development of equipment can be expected in the near future which will offer adequate radar image enhancement and target identification and, possibly, data transfer capabilities;

    f) that such shipborne transponders may require protection from interference;

    g) that the selection of technical characteristics for these transponders should be coordinated with other users of the radio frequency spectrum whose operations might be affected;

    ' request the CCIR '

    to recommend, after consultation with appropriate international organizations, the most suitable order of frequencies and bandwidth required for this purpose, and the technical parameters to be met by such devices taking into account electromagnetic compatibility with other services having allocations in the same frequency band;

    ' invites administrations and the Inter-Governmental Maritime Consultative Organization (IMCO) '

    to continue to evaluate the operational benefits which could result from the widespread use of transponders on ships and to consider whether there would be advantage in adopting an internationally approved system for future implementation;

    ' recommends '

    that, pending further technical and operational developments and evaluation, administrations be prepared at the next competent world administrative radio conference to make the necessary provisions for the use of such devices.


    Document No. 3 (' cf. supra, ' p. 1251)

    RECOMMENDATION No. 713 (Mob-83)

    Relating to the Use of Radar Transponders for Facilitating
    Search and Rescue Operations at Sea

    The World Administrative Radio Conference for the Mobile Services, Geneva, 1983,

    [p.1255]

    ' considering '

    a) that a search and rescue system, composed of shipborne radars operating in the 9 GHz band in combination with radar transponders which respond to radio signals transmitted by the shipborne radar, could be a practicable means of position-finding for a unit in distress at sea;

    b) that this system would make use of radars operating in the 9 GHz band already installed on board ships and aircraft engaged in search and rescue operations and could contribute greatly to search and rescue operations at sea;

    c) that this system would be more effective, if the small-size, light-weight and low-cost radar transponders were in conformity with internationally agreed technical and operating characteristics;

    d) CCIR Questions 28/8 and 45/8, and in particular the studies on homing on emergency position-indicating radiobeacons;

    ' requests the CCIR '

    to include in its studies on the future global maritime distress and safety system (FGMDSS) the technical and operating characteristics of radar transponders for facilitating search and rescue operations at sea.

    ' recommends administrations '

    to study this matter and submit contributions to CCIR,

    ' invites the Secretary-General '

    to bring this Recommendation to the attention of the International Maritime Organization (IMO), the International Association of Lighthouse Authorities (IALA) and the International Civil Aviation Organization (ICAO).


    NOTES (1) [(1) p.1248] ' CE/7b ', pp. 46, 52-54; ' CE 1972, Technical Memorandum ', pp. 12-13, 36-39, 44-52 (Annex II); ' CE 1972, Report ', Vol. I, p. 53, para. 2.2.2; ' Commentary Drafts ', pp. 123-124 (Art. 11);

    (2) [(2) p.1248] O.R. XIII, p. 29, CDDH/49/Rev.1, paras. 36, 38;

    (3) [(3) p.1249] Cf. Resolution 17 annexed, together with Resolutions 18 and 19, to this commentary, infra, p. 1513;

    (4) [(4) p.1249] Cf. Annex 10 to the Convention on International Civil Aviation (Chicago, 7 December 1944), hereinafter referred to as ICAO, Annex 10, Aeronautical Telecommunications, Vol. I, Sections 2.5 and 3.8, Attachment B;

    (5) [(5) p.1250] Ibid., paras. 3.8.1.1, 3.8.2.1;

    (6) [(6) p.1250] ' CE 1972, Report ', Vol. I, p. 54, para. 2.2.2.1;

    (7) [(1) p.1253] A receiver-transmitter which emits a signal automatically when it receives the proper interrogation;

    (8) [(2) p.1253] Replaces Recommandation No. Mar2 - 14 of the World Maritime Administrative Radio Conference, Geneva, 1974;