Sub-Group N2 ATN Air-Ground Applications

ACP/WGN

WP/8-MM

ICAO ACP SG-N2/8 Minutes

Issue 1

AERONAUTICAL COMMUNICATION PANEL

Sub-Group N2 – ATN Air-Ground Applications

ICAO Regional Office, Bangkok, Thailand
25 – 26 January 2006

REPORT OF 8th MEETING OF SG N2

1Meeting Organisational Issues

WP8/01 List of Attendees

WP8/02 List of WPs

The eight meeting of the ICAO Aeronautical Communications Panel, Working Group N, Sub-Group N2 was held in Bangkok(Thailand) on the 25th of January 2007. The meeting was chaired by Frédéric Picard and was attended by3 experts and the ACP Secretary, a list of the attendees is attached as Appendix C. Theworking and information papers presented and discussed during the meeting are listed in Appendix B.

The ICAO Regional Office, with the support of Aerothai,hosted the meeting in Bangkok. The WGN/7 meeting took place the following week.

2Approval of the Agenda

WP8/00 Agenda

The agenda was agreed by the SGN2 group and the meeting proceeded with the agenda attached in Appendix A.

3Agenda Item 2: Notes and Actions from previous ACP Meetings (SGN2/7 and WGN/6 – Brussels, Belgium, June 2006)

WP8/03 Report of SGN2/6 – Atlantic City March 2006 (SGN2 Chairman)

IP8/10 Approved Report of ACP WGN-06 meeting (WGN Rapporteur)

The actions issued from the SGN2/7and WGN/6meetings were reviewed.

Alignment of CPDLC specifications to the CPDLC Message Set output from OPLINKP/1

SGN2 has analysed the impact of the new CPDLC message set output from OPLINKP/1 and recommended WGN/6 to not align the CPDLC specification, but rather wait for the publication of the amended Doc 4444 before doing it. Current Doc. 9880 is fully aligned with Amendment 4 to the 14th Edition. Since the AMSG has been disbanded, the support by CPDLC of the new message set must now be carried out by the ACP maintenance working group (WG/M).When the operational need to use the new message set will arise, a change request will have to be submitted to WG/M. As far as SGN2 is concerned, the action is closed.

NewCPDLC Message: “UM238 CURRENT ATC UNIT IS”

At the initiative of AIRBUS, a new CPDLC uplink message was proposed for inclusion in the CPDLC message set. This message would be used by the aircraft to automatically enable the pilot to send downlink messages from the airborne HMI (Human-Machine Interface). With the current message set, the ground system uses the uplink free text message (UM183) which cannot be processed by the airborne automation. After co-ordination between the ACP and OPLINKP Secretaries, the proposal was rejected, on the ground that any new CPDLC message must first be analysed and endorsed by an operational body. If the need for such a message is confirmed, a change request on Doc 4444 / Doc 9694 and Doc 9880 should be sent to ICAO. The action is closed for SGN2.

ADS-C application improvements (PM)

Since the last meeting, work has been performed in this area, resulting in the production of a new ADS-C specification (draft version 0.4). This will be discussed later during the meeting. The action is closed.

PM-FIS completion

Since the last meeting, validation on PM-FIS has been completed, resulting in the production of a FIS Validation Report by Eurocontrol. This will be discussed later during the meeting. The action is closed.

Technical support to PDR resolution

No PDR pertaining to air/ground ATN applications has been submitted to the SG. As the ACP AMSG has now been disbanded, any defect found in ICAO documents 9705 or 9880 must be notified to the maintenance ACP WG/M for consideration. Asthe AMSG procedures have been widely and extensively used for several years by the data link aeronautical community, there is anurgent need that the new maintenance procedures in force in WG/M are made known to the users of Doc 9705 and 9880. The action is closed for SGN2.

4Agenda Item 3: Briefing from Relevant Meetings

4.1ADS accommodation drafting group(ADG) activities

WG/N was informed in Brusselsthat the DLSG (ICAO Data Link Steering Group) has established an ATN Accommodation Working Group (ADG) to assess the feasibility of accommodating ATN aircraft in a FANS-1/A environment. This group is considering work on ADS as a part of convergence work, moving towards a single air/ground datalink system covering oceanic and continental airspaces. ADG/3 has met in December 2006 in the European and North Atlantic ICAO Office in Paris. FP reports about this meeting.

Based on FANS experience of ADS, several potential operational changes have been discussed. Some examples are listed below:

1. allocation and management of a “contract number” to all ADS contracts;
2. use of “latitude/longitude” instead of “bearing/distance” in the intent reports;
3. combinationof “intent profile” and “extended profile” in a single profile;
4. replacement of the emergency contract by a simple emergency flag in all reports;
5. definition of new triggering events for ADS-event-contract, such as weather deviation (DUE TO WEATHER), or vertical deviation;
6. inclusion of additional data types in ADS reports, such as way-point names.

The SG recognizes that these changes are outside the scope of the SGN/2 Terms Of Reference and need to be discussed and endorsed by an operational body (such as OPLINKP or anad-hoc Task Force), before being translated into technical provisions. The ADG is currently working on a proposed amended Doc 9694 addressing these issues. As a consequence, the changes listed above will not be addressed by SGN/2, until the sub-group is tasked to do it.

It is noted that with the protected mode, most of the changes listed above are now transparent to the communication protocol and will not necessitate an update of the protocol.

Items 1 and 2 are discussed by SGN/2 in more detail:

1. Contract number. In the current version, no contract number is allocated to the ADS contracts since there is no real need for it: each ADS report is associated with a contract type (demand, event, periodic or emergency) and only one contract type is allowed between the aircraft and the ground at any time.

The support of a contract number in PM-ADS would require a change of the ASN.1 definition of the ADS APDUs, with potential impact on interoperability if it is not included in the initial version.

The contract number appears to be a “nice to have” feature which would facilitate the ADS activity monitoring and to allow direct mapping between an ADS report and a contract, in case of establishment of successive contracts of the same type. This feature exists in FANS (but the contract number is only included in the ADS requests, not in the reports themselves).

The SG agrees that since this feature is only a useful add-on but does not seem mandatory for the ADS operation, this will be implemented in a later version.

1. Lat/lon in ADS report. The ADS report (in the current version) identify way-points by the bearing/distance indication from the previous way-point. This can introduce errors in the precision of the route. Replacing bearing/distance by lat/lon is a simple change that has no effect on operation but would enhance the precision of the reporting route.

SGN2 agrees that it is a minor change that could be done from the initial version of PM-ADS if the use of lat/lon in ADS report is formally agreed by the OPLINKP/ACP Secretaries.

Action: A change proposal should be sent officially by ADG to R. Kruger (Deputy Director of EUR/NAT Office) or by SGN2 to R. Witzen (ACP Secretary).

ADG/3 also supports the following technical changes:

Definition of a protected mode for ADS to address integrity and mis-direction hazards,

Re-designof the ADS-C Application as independent of the underlying communication network, with appropriate interface capabilities to enable use of the application above the ATN/ISO network, the ACARS (FANS1/A) network, or future network such as ATN/IP.

The SG notes that these changes are already addressed in the current specification (see Agenda Item on ADS-C below).

5Agenda Item 4: Status of ICAO Doc 9880

IP8/1 to IP8/8 Draft Doc. 9880: Manual on Detailed Specifications For the Aeronautical Telecommunication Network using ISO/OSI standards and protocols (ACP Secretary).

RW presents Doc 9880. The document contains CM and CPDLC in Part I. ADS-C and FIS material are missing. The document is ready for publication as CD-ROM, however this can take a while; no formal date can be given.

Although the current version has already been endorsed by the ICAO Secretary General, changes can still be proposed. Comments must be submitted to RW. After ACP/1, the changes will be sent to WGM. There is a form available to document the change proposal. The change proposals will then be placed on the ICAO web site, as a WP for the next WG/M meeting. The exact procedures and supporting means within WGM are still to be defined.

Some comments are provided to RW during the meeting.

Action Review Doc. 9880 and provide comments to ACP Secretary.

6Agenda Item 5: Protected-Mode FIS (PM-FIS)

6.1Status of the SGN2 deliverables for PM-FIS

The status of the PM-FIS deliverables is provided to SGN2.

Technical provision (Doc 9705 Sub-volume II, Doc 9880 Part I, chapter 4). Current version is 0.4 (see ACP WGN/6 WP20)

The document is complete and validated. However, to allow inclusion in Doc. 9880, translation of the WordPerfect files into MS Word files is still to be performed. Also, some editorial changes are to be applied, similar to those done on the PM-CPDLC specification (new section numbering, removal of references to the “protected” mode, etc…).

Guidance material

The Guidance Material produced on PM-FIS has been reviewed at the last SGN/2 meeting and presented to WG/N (see WGN WP 6/20). This is a redline version against Edition 1 Doc 9739 guidance material. It is fully aligned with PM-FIS version 0.4.

P/OICS

P/OICS pro-formas are made available to regional bodies and industry to support specification of operational profiles and product capabilities on a consistent manner using excel sheets. PM-FIS P/OICS are available for both air and ground systems and are aligned with Version 0.4.

These documents are not presented again to SGN/2 and WG/N. The files presented at Brussels in June 2006have not been modified since then and are still fully applicable. All files are available on the ICAO web site under WGN Meeting #6 (WP20).

6.2Validation Report

WP8/4PM-FIS Validation Report (Eurocontrol)

Eurocontrol has launched a validation project in 2006 to ensure validity and completeness of the PM-FIS specification produced by SGN2. In June 2006, intermediate results were reported to SGN2 and WGN based on the implementation of the air and ground PM-FIS ASEs into 2 different ATN End Systems. After June 2006, interoperability tests between the 2 systems have been successfully run. The defects detected during the validation reported have been resolved in the June version of the specification. The validation report documents the approach followed during the test, lists the defects and the agreed SGN2 resolution. It also analyses each of the validation objectives (as defined and used for the validation of other air-ground ATN applications)and concludes that all VOs are meet. This allows to claimfor PM-FIS a validation level ‘b’ (i.e. 2 implementations by one state or organisation).

SGN2 recommends the WGN to endorse the current PM-FIS specification.

7Agenda Item 6: Protected Mode ADS (PM-ADS)

7.1PM-ADS Specifications

WP8/05 PM-ADS specification Draft 0.4

The new specification takes into account the directions given by WGN at the last meeting. The 3 main changes are discussed during the meeting:

Decoupling the ADS application-user from the ADS ASE functions

The User/ASE functions decoupling is a pre-requisite to the integration of PM in the ADS protocol. Operational data (such as the ADS request, ADS Reports) are now passed as transparent data to the ASE along with the checksum. The contract management data that were before included in the operational data are now defined as separate parameters at the Application Service Interface (ASI). It is reminded that the ASI is a functional interface, and the software implementation is not required to implement it (local design issue). This approach was the one selected by WG/N in last WG/N meeting.

Inclusion of the PM functionality

The protected mode is now supported by the ADS-C Application on the same principles followed for CPDLC. Application-users are responsible for creating a message checksum based on the encoded message, the identity of the aircraft (24bit address, flight ID), the identity of the ground (Ground Facility Designator), and the identifier of the used message set. The validity of the checksum upon receipt of a message guarantees the integrity and the routing of the message.

Decoupling the ADS-application from the underlying sub-network

To support transition of the ADS-C application towards other existing network or new networks, it is desirable to modify the design of the application to allow porting the application another network without any impact. This capability was already build in the current ADS-C Application since the “Low Interface” module (LI) specifies the mapping onto the ATN Dialogue service. Alternate LI modules could be defined for other interfaces.

WP8/07Boeing Comments on PM-ADS

Co-ordination has been made by mail and teleconferences between the main contributors (Airbus, Boeing, Eurocontrol, DTI). The comments received from S. Gordon (Boeing) and other comments issued during the meeting are discussed and summarized below:

1. Re-use of same terms (e.g. ADSReport) in the APDU ASN.1 and in the ADS message ASN.1. Comment is agreed. The ASN.1 will be change accordingly.
2. With PM, some ADS service primitives contain parameters that are transparent to the ASE. To manage the contracts, some of this information needs to be made visible to the ASE. Comment is agreed. This has been addressed in the current specification with this information excluded from the operational data and defined as separate primitive parameters.
3. In 2.2.1.5.3.1.1, the note 2 must be validated and figures modified accordingly. Comment is agreed.
4. In section 2.2.1.7.3.3, application-users are required to clean up the aircraft flight id (e.g. suppression of the space) and to follow a strict syntax (3 letters for the aircraft operating agency + flight number with no leading zeroes). This requirement is too stringent, not all aircraft operators follow this rule. The original requirement that the syntax used must be the one filed in the ground flight plan is sufficient. This need to be investigated (might have an impact on PM-CPDLC). Comment is open.
5. In 2.2.1.7.2.1.6, the term” first downlink ADS message” must be described (it is the first uplink or downlink message over the underlying dialogue, not the first over the ADS contract). Comment is agreed.
6. State tables must be aligned with the text description of the protocol. Comment is agreed.
7. Tables in 2.2.15 must be titled. Comment is agreed.
8. All reference to the ADS-forward must be deleted in 2.2.1 (e.g. 2.2.1.7.1.2). Comment is agreed.

SGN2 participants (namely Boeing, Airbus, DTI, ACP Secretary) believe the current version is mature enough to be presented to the WGN for consideration and to allow start of the validation activity.

7.2Other Documents

No guidance material nor P/OICS have been produced yet for PM-ADS.

Action. SGN/2 members are invited to participate in the production of ADS GM and P/OICS.

7.3PM-ADS Validation Activities

The PM-ADS validation is not started.Eurocontrol is about to start a validation task in 2007.This will take the same form than the PM-FIS validation, however only a single PM-ADS mock-up will be realized.

7.4Planning for PM-ADS Activities

The following planning is presented:

January 2007: presentation to and endorsement by WG/N of the ADS-C draft specification (V0.4). Start of validation agreed.

Validation: from January to June 07.

Summer 07: Presentation of the validation result and endorsement of ADS-C final specification by TBD.

8Agenda Item 7: Other Technical Matters

No other technical matter is discussed.

9Agenda Item 8: Input to Working Group N Meeting

The following documents will be presented to WGN:

• WP7/13 SGN2 Report to WGN
• WP7/16: PM-FIS Validation Report
• WP7/17: PM-ADS Draft Specification – Version 0.4

10Agenda Item 9: A.O.B.

No A.O.B is discussed.

11Agenda Item 10: Future Work and Date of Next Meetings

No meeting is planed yet.

F. Picard

Chairman, ACP WGN SG N2

Bangkok, Thailand. 26January 2007.

Appendix A

AGENDA

for

THE 8th MEETING OF ACP WGN/SGN2 (Air/Ground Applications)

in

ICAO Regional Office, Bangkok, Thailand

25 – 26 January 2006

1. Approval of Agenda [WP8/00]

1. Notes and Actions from previous ACP Meetings (SGN2/7 – Brussels, Belgium, June 2006) [WP8/03]

1. Briefings from Relevant Meetings

1. Status of ICAO Doc 9880 [IP8/01 to IP/09]

1. Protected Mode FIS (PM-FIS)

5.1Review of Validation Report [WP/04]

1. Protected Mode ADS (PM-ADS)

6.1Review of draft PM-ADS Specification [WP/05]

6.2Validation Activities

1. Other Technical Matters

1. Input to Working Group N Meeting (07), 29th January -2nd February 2007, Bangkok
2. Deliverables

1. AOB

1. Date of next meeting

End

Appendix B: List of Working Papers

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