Appendix 2 – Technical Matters
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Statutory Documents - IMO Publications and Documents - Circulars - Maritime Safety Committee - MSC.1/Circular.1412/Rev.1 – Principles and Guidelines Relating to the Review and Audit of the Performance of LRIT Data Centres and of the International LRIT Data Exchange – (21 November 2014) - Appendix 2 – Technical Matters

Appendix 2 – Technical Matters

  1 The LRIT Coordinator is not expected to engage in any audit, verification or investigation as to the existence, accuracy or veracity of Notices of Arrival in connection with requests for the provision of LRIT information pursuant to the provisions of regulation V/19-1.8.1.2 and in this respect Notices of Arrival should be considered as being outside the scope of the review and audit.

  2 In order to verify compliance with the provisions of paragraph 13.1 of the Revised performance standards, TimeStamp1 and TimeStamp4 of the LRIT position report message should be used. The time duration established by the difference between TimeStamp1 and TimeStamp4 of the LRIT position report message should be less than 15 min. Furthermore, the latency between the transmitting DC sending the LRIT information to the end user should be considered as being negligible (i.e. of the order of seconds).

  3 In order to verify compliance with the provisions of paragraph 13.2 of the Revised performance standards on-demand LRIT information should be considered as a poll request and the TimeStamp parameter of the LRIT position request and the TimeStamp4 of the LRIT position report should be used. The time duration established by the difference between TimeStamp parameter of the LRIT position request and TimeStamp4 of the LRIT position report message should be less than 30 min. Furthermore, the latency between the transmitting DC sending the report to the end user should be considered as being negligible (i.e. of the order of seconds). Additionally, if for any reason it is found necessary to use alternative sources to verify such compliance, the LRIT Coordinator should use the Rx and Tx TimeStamps contained in the IDE's journal for the LRIT position request and LRIT position report messages.

  4 Each port, port facility or place under the jurisdiction of a Contracting Government should be considered as the centre of a circle and the distance indicated in the LRIT position request as corresponding with the radius of the circle. The difference on the calculation of the distances using different chart projections should be considered as being irrelevant, in terms of the precision required by the LRIT system as in most cases the ships are in motion when transmitting LRIT information.

  5 When the entitlement of Contracting Governments to LRIT information is verified, it should be taken into account that different DCs and the LRIT Coordinator may utilize different GIS implementations, which may occasionally yield slightly different interpretations of where a ship is located in relation to DDP-defined polygons. This may result in occasional, legitimate technical differences between the LRIT Coordinator and the audited DC when determining which Contracting Governments are entitled to a particular ship position.

  6 If DCs and the LRIT Coordinator use industry-standard GIS software applications, or custom-coded solutions that implement well-established computational geometric algorithms, the occurrence should be rare. The LRIT Coordinator may determine, on a case-by-case basis, if the differences between its own entitlement determinations and those of the audited DC are sufficient to warrant detailed analysis.

  7 DCs should provide to the LRIT Coordinator all LRIT Messages with the exception of the file attachments associated with Message 10 (DDP Update) and Message 12 (Journal). All LRIT messages are required to have a unique MessageId parameter.

  8 LRIT position reports that have not been transmitted to any other DCs until the time of the information for the review and audit is provided should be classified as Message type 1 with Response type 2 when provided to the LRIT Coordinator. The parameters TimeStamp5, DataUserRequestor and the attribute positionSent of the LRIT position reports that have not been transmitted to any other DCs should be populated with values as follows:

  • .1 TimeStamp5 = dummy value (i.e.1000-01-01T00:00:00Z)

  • .2 DataUserRequestor = 0003 (the LRIT ID of the LRIT Coordinator)

  • .3 positionSent = false

  9 The IDE should provide its journal with the exception of the file attachments associated with Message 10 (DDP Update) and Message 12 (Journal). The parameters Latitude, Longitude, TimeStamp1 and ShipborneEquipmentId of the LRIT position reports should be populated with values as follows:

  • .1 Latitude = dummy value

  • .2 Longitude = dummy value

  • .3 TimeStamp1 = dummy value (i.e.1000-01-01T00:00:00Z)

  • .4 ShipborneEquipmentId = dummy value

  10 All information contained in the audit files should be in XML and in the English language encoded in UTF-8.

  11 DCs should provide to the LRIT Coordinator, upon request, a file <LRITMessageLog_LRIT ID of the DC>.xml.footnote

  12 The IDE should provide the LRIT Coordinator, upon request, a file <LRITMessageLog_LRIT ID of the IDE>.xml.footnote


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