Boeing Bulletins

FMC-3 : Pegasus Flight Management Computer (FMC) Departure Routing Anomaly

1 June 2009

Effectivity

Please refer to source document.

Reason

To inform flight crews of a Pegasus-FMC anomaly regarding route discontinuity removal between a selected departure and the active route.

Information in this bulletin is recommended by The Boeing Company, but may not be FAA approved at the time of writing. In the event of conflict with the FAA approved Airplane Flight Manual (AFM), the AFM shall supersede. The Boeing Company regards the information or procedures described herein as having a direct or indirect bearing on the safe operation of this model airplane.

Background Information

Boeing has confirmed operator reports of a Pegasus-FMC anomaly related to removal of a route discontinuity between a selected departure and the active route. Boeing engineering has confirmed this software anomaly may occur if a route discontinuity is removed using the RTE page 2 instead of using the RTE LEGS page. Some operator reports indicate the waypoint identifier disappears from the scratch pad when line-selected into the discontinuity boxes, but the RTE page title never indicates the route modification, hence the entry attempt is not successful. And in some cases, a subsequent FMC lockup may result.

Honeywell is aware of this Pegasus-FMC anomaly. The planned fix to the problem is under investigation.

Operating Instructions

To prevent the occurrence of this anomaly, removal of route discontinuities between a selected departure and the active route using the RTE LEGS page instead of RTE page 2 is recommended.

Administrative Information (Extract)

This Flight Crew Operations Manual Bulletin will be revised to include service bulletin information when available.