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A321 captain reports fmgec selecting cruise speed of mach .71 at FL330; which was below vls at the time. Speed was manually selected to mach .79 and flight continued to destination.
| Attributes | |
| ACN | 842641 |
| Time | |
| Date | 200907 |
| Local Time Of Day | 0001-0600 |
| Aircraft 1 | |
| Make Model Name | A321 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | FMS/FMC |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe |
Narrative:
When capturing our cruise altitude of FL330; I heard the engines spool down. When I glanced up at the pfd; I noticed the aircraft was slowing to a managed speed of mach .71. Mach .71 was below vls speed at FL330. Max cruise altitude was showing as FL334. I selected mach .79 and we continued on to destination. I tried to investigate why our managed speed was indicating only mach .71. I pulled up info to see if there was a discrepancy in the aircraft weight and the facility computed weight. There was no appreciable difference. I contacted maintenance control and they advised me that this was a recurring problem on the A321 but did not know why. The current leg report in the mcdu had 1 item listed 'liqd lvl xmtr' which I was not familiar with. Incident should be investigated. Pilots should be made aware of this anomaly so that further incidents could be tabulated to see if the problem is widespread.
Original NASA ASRS Text
Title: A321 Captain reports FMGEC selecting cruise speed of Mach .71 at FL330; which was below Vls at the time. Speed was manually selected to Mach .79 and flight continued to destination.
Narrative: When capturing our cruise altitude of FL330; I heard the engines spool down. When I glanced up at the PFD; I noticed the aircraft was slowing to a managed speed of MACH .71. MACH .71 was below VLS speed at FL330. Max cruise altitude was showing as FL334. I selected MACH .79 and we continued on to destination. I tried to investigate why our managed speed was indicating only MACH .71. I pulled up info to see if there was a discrepancy in the aircraft weight and the FAC computed weight. There was no appreciable difference. I contacted Maintenance Control and they advised me that this was a recurring problem on the A321 but did not know why. The current leg report in the MCDU had 1 item listed 'LIQD LVL XMTR' which I was not familiar with. Incident should be investigated. Pilots should be made aware of this anomaly so that further incidents could be tabulated to see if the problem is widespread.
Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.