A320
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 250; Flight Crew Total 11000; Flight Crew Type 7500
Confusion; Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Overcame Equipment Problem; Flight Crew Returned To Clearance
Aircraft; Human Factors; Procedure
Prior to takeoff Clearance Delivery provided a full route reroute. The First Officer loaded new route and I verified the new route was loaded correctly. After departure; flight was given direct LAS. The First Officer inserted direct LAS; which I verified; and engaged with 'abeam points'. The First Officer loaded en route winds into flight plan. During loading; the First Officer remembers seeing the route with J100 from LAS to SNY while loading BCE winds. Shortly after passing LAS; Center asked if we were on J100. We responded we were supposed to be and checked the FMGC route. The route now showed LAS direct to SNY with no 'abeam points'. We corrected it and got back on course. We do not know how the route got changed. Less than two minutes later; the same thing happened to another air carrier flight behind us. The most likely explanation would be that one of us mistakenly inputted a 'direct SNY'. However; the First Officer's technique would be to program such a change including 'abeam pts'. They were not there. The First Officer does not remember making that input and I did not verify any such input. This makes that mistaken input somewhat less likely. I did not make any inputs. We are at a loss to explain what actually happened. Since the same thing happened to the next flight; at the same point; on the same route; on the same day; at almost the same time; there is a small possibility that there is a database or other FMGC glitch. This is worthy of further investigation.
An A320 flight crew received a reroute clearance prior to takeoff and programmed the FMGC accordingly. Inexplicably; after takeoff when ATC inquired as to their deviation from that route they found the programmed 'airways' route between LAS and SNY had vanished and was now showing a 'direct' route. Strangely enough; another air carrier A320 flight crew flying the same route shortly behind them reported what appeared to be an identical anomaly.