Working Group B


Working Group B (WG-B) held one meeting in January (WG-B/14) and one meeting in May (WG-13/15). WG-B continued to develop frequency assignment planning material, including relevant guidance material, for VHF digital link (VDL) Modes 3 and 4 and to assess the availability of a global signalling channel for VDL Mode 4. A long discussion took place in WG-B on the on-board integration of VDL Mode 4, with regard to problems identified by Airbus and Boeing with implementing VDL Mode 4 on an aircraft. Progress on this issue, that would involve VDL Modes 2 and 3 as well, is hampered by the lack of technical data, specifying the origin of the problem reported. WG-B also noted that VDL Mode 4 could be more susceptible to interference from DSB-AM and VDL Mode 2 systems than was expected. This may also require further consideration with regard to the interference susceptibility for VDL Modes 2 and 3. WG-B/15 addressed these problems further, in particular on the basis of detailed technical information provided on VDL Mode 2 and 3 on-board interference issues. With regard to VDL Mode 4 interference issues, the meeting concluded that Airbus needed to provide detailed technical information to WGB to substantiate its conclusions on VDL Mode 4 implementation.


Working Group C


WG-C held one meeting in October. In addition, a number of meetings of the universal access transceiver (UAT) sub-group were organized. During these meetings, the work on draft Standards and Recommended Practices (SARPs) for the UAT progressed and the validation phase of the draft SARPs has been started. It is expected that during 2005 the draft SARPs for UAT are complete and can be submitted to ACP for consideration. WG-C also considered results of a study, based on an increased deployment of 8.33 kHz channel spacing, predicting saturation in the VHF band in Europe by 2015. In the United States, saturation of the VHF band, based on the current 25 kHz channel spacing, seems to occur in the same time frame. WG-C continued its evaluation of potential technologies for future mobile communication systems with the view to complete this activity by 2005.


Working Group F


Working Group F held one meeting (WG-F/10) in August in Montreal. With regard to the items to be addressed at ITU WRC-07, WG-F/10 stressed the need to secure spectrum for telemetry purposes, in particular for use by Unmanned Aerial Vehicles (UAV), future AM(R)S systems and, in the 5 GHz band, for ANLE and aeronautical fixed links, to be used on airports. Also, the limited access to the L-band for satellite communications (as a result of a decision taken at WRC-97) and the need for spectrum for future (aeronautical) next-generation satellite systems (NGSS) was discussed. WG-F/10 was informed on work that is being undertaken by RTCA on interference that can be caused by personal electronic devices that are carried on board an aircraft by passengers. The protection of radars in the frequency band 2 700 -2 900 MHz, planned for use by some administrations for Electronic New Gathering/Outside Broadcast (ENG/OB) was considered. The need for individual assessment of interference, based on the characteristics of the interfering signal, was raised. Subsequent to the meeting, in response to a query originated by WG-F, ICAO was informed by the Radiocommunication Bureau of the ITU that an allocation to the aeronautical mobile (R) service would be required in the DME band to support UAT operation.


Working Group M


WG-M held two meetings, one in April 2003 (WG-M/7) and the second in November 2003 (WG-M/8). The Commission had decided that the maintenance of ATN SARPs and guidance material would be added to the work programme of WG-M. In addition to its maintenance activities of SARPs and manuals, WG-M is involved in implementation issues for communication systems, including on-board integration of systems and coordinates its activities closely with those of WG-B.
WG-M/7 completed the VDL Mode 4 validation, as required by AMCP/8, by reviewing the results of the flight testing with the new data link service (DLS) protocol. The Commission was informed accordingly when it reviewed the report of AMCP/8. WG-M/7 further addressed the difficulties, identified by Airbus, with the integration of VDL Mode 4 on board aircraft. WG-M could not draw any conclusions since the information available was lacking technical details. This matter was also considered at WG-B (see above). WG-M reviewed proposals from the Secretary to split the aeronautical mobile-satellite service (AMSS) SARPs in a set of core SARPs and material that would be incorporated in a new technical manual and agreed to integrate the next-generation satellite systems (NGSS) SARPs, developed by AMCP/7, in the core SARPs and to move most of the current detailed AMSS material into a manual. WG-M/7 also addressed the need to amend in the current SARPs the table of unwanted emission limits from on-board AMSS stations with the view to protect in particular GLObal NAvigation Satellite System (GLONASS) systems.
WG-M/8 considered the organization of its future work on the maintenance of ICAO ATN material. A combined meeting of Working Groups M and N was organized to review arrangements for the maintenance of ATN SARPs and guidance material. At this meeting, a combined subgroup for WGs-M and N was created (ATN Maintenance Subgroup, AMSG) which should develop amendments to the ATN material, in close coordination with WGs-M and N, as required, and report in any case to both WGs-M and N with each working group taking action within its mandate. Discussion items between WGs-M and N should be solved through direct coordination. Further amendments to the VDL Mode 4 manual were agreed. WG-M/8 was informed that on-board interference from DSB-AM voice systems into VDL (Modes 2, 3 and 4) would most likely be more critical than vice versa. Work on this matter is ongoing.


Working Group N


WG-N held two meetings in 2003, WG-N/1in May in Montreal, Canada, and WG-N/2 in November) in Bangkok, Thailand. WG-N/1, which had a more organizational character, reviewed its work programme and created four sub-groups, as follows:


  • SG-N/1: Internet communication services;
  • SG-N/2: Air-Ground applications;
  • SG-N/3: Ground-Ground applications; and
  • SG-N/4: Security Services.
The work in WG-N on the use of Transmission Control Protocol/Internet Protocol (TCP/IP) in aeronautical communication is progressing and concentrated in the following issues:
  • the IP subnetwork dependent convergence function (SNDCF) which makes it possible for the ATN internet and its applications to operate over a TCP/IP ATN sub network;
  • the assessment of a potential wider use of TCP/IP protocols in aeronautical networking; and
  • the system-wide information management system, currently being developed in one State.
Reports on these issues, together with any other relevant material, are expected to be completed at the time of ACP/1, for review by the panel.
Continuing work in the area of air-ground applications required close coordination with the Operational Data Link Panel (OPLINKP) as the main source for the relevant operational requirements. WG-N was awaiting formal approval from OPLINKP for developing SARPs and/or guidance material in response to new or enhanced operational requirements for controller-pilot data link communications (CPDLC), which had been specified by European Organisation for Civil Aviation Equipment (EUROCAE).
Although the ATN directory services were included in Edition 3 of Doc 9705, further expansion was necessary. The impact of migrating ATN directory services to TCP/IP (sub) networks and the use of LDAP as an alternative directory service for (sub) regions with a TCP/IP structure required further work. Results on these subjects are expected to be available at ACP/1.


WG-N was informed about several projects under way on the introduction of the ATS message handling system (ATSMHS) and noted the European strategy for implementing TCP/IP in the ground-ground network and the ATN in the air-ground sub-network. WG-N was informed on plans of the World Meteorological Organization (WMO) to replace alphanumerical codes with binary universal form for the representation of meteorological data (BUFR) codes in aeronautical meteorological messages, starting from 2007. As a possible consequence, all AFTN terminals should be capable of receiving binary data by 2015 and, from 2007, to deliver TDCF (binary) data. The potential support of this requirement by ATS message handling system (AMHS) will be studied by WG-N.


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