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Problem Description • Problem 1:If a UM79 does not repeat the “TO” point, after sequencing the last waypoint before the “TO” point the aircraft begins flying towards the last waypoint prior to the “TO” point from previous route data. The magenta line on the Nav Display between this point and the “TO” point disappears • Problem 2: If a um79 repeats the “TO” point, the FMC does not collapse the duplicate waypoints to one, forcing the airplane to do several turns after sequencing that waypoint before intercepting the Flight path unless the crew collapses them • Only applicable to um79 • Prototype fix received and being checked • Awaiting documentation on the root cause • B747-400, B747-8 checked • B777, B737, and B757/B767 complete by this Thursday
Boeing Planned Actions • Updates in -922 FMC change (mid-2014 certification) • Problem 1 will be resolved (considered a must fix) • Problem 2 is lower priority, and is therefore fighting for space and funds (status not known yet) • Once the root cause has been confirmed by Honeywell, Boeing will issue the following two IOPs : • IOP 1 (simplified versions – draft IOP will be more complete): Part 1: When presented with UM79, after loading the message, the crew is to delete the last waypoint of the revised clearance from the UM79 message and re-enter it manually in order to avoid Problem 1. Parts 2: If Part 1 of this IOP is missed and the problem occurs in flight, after the anomaly is seen the crew should select a heading that will return the airplane to the cleared route of flight • Specific details on crew interactions with the MCDU and ND are in the draft IOP • IOP 2: After loading of the UM79, if duplicate waypoints are present on the MCDU, the crew should delete one of the waypoints. This is the work-around for Problem 2
Impact on FAA DCL Service • No change to TDLS / Operational system requirements • -922 will be available prior to IOC, so existing end-to-end requirements apply. • Specifically: For UM79, when the “TO” point is also an airway termination point for an airway that’s the last element in the routeinformation field, DTAP will include the “TO” point as the last element in the routeinformation field after the airway. For UM79, when the “TO” point is not an airway termination, DTAP will not include the “TO” point as the last element in the routeinformation field. • DTAP change to support MD-11 Revisions via UM79 For UM79, DTAP will include the “TO” point as the last element in the routeinformation field Crews will need to use IOP 2 Airbus confirms acceptable from their perspective
