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B757 flight crew notices vmo pointer at an abnormally low position (270 knots) during climbout and elects to return to departure airport.
| Attributes | |
| ACN | 863837 |
| Time | |
| Date | 200912 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Initial Climb |
| Route In Use | Other Controlled |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Airspeed Indicator |
| Person 1 | |
| Function | Captain Pilot Flying |
| Person 2 | |
| Function | Pilot Not Flying First Officer |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy |
Narrative:
Start; taxi; takeoff were normal. Climbing through approx 12;000 ft; I noticed the vmo/mmo pointer remaining stagnant at approximately 270 KTS. As we climbed it was obvious that we would get an overspeed warning if the climb was continued. I requested a level off and slowed to 250 KTS. I contacted dispatch and maintenance to discuss the problem and a decision was reached to return. The remainder of the instruments seemed normal and since I was not sure what had caused the anomaly; we elected to return immediately. Landing weight was checked on final at 210;000 pounds and an uneventful landing was accomplished. After shutdown; a maintenance supervisor advised us that the vmo/mmo switch was in the incorrect aux position rather than normal position. Although the position of the switch is not accessible by aircrew both the first officer and I failed to note that the mach pointer was lower than normal during preflight. The pointer is not acutely lower than normal in this condition and in nearly 14 years on this airplane I have never seen this before. Although I checked the indicator I just did not notice the low mach pointer. I will certainly in the future pay particularly close attention to this detail.
Original NASA ASRS Text
Title: B757 Flight Crew notices VMO pointer at an abnormally low position (270 knots) during climbout and elects to return to departure airport.
Narrative: Start; taxi; takeoff were normal. Climbing through approx 12;000 FT; I noticed the VMO/MMO pointer remaining stagnant at approximately 270 KTS. As we climbed it was obvious that we would get an overspeed warning if the climb was continued. I requested a level off and slowed to 250 KTS. I contacted Dispatch and Maintenance to discuss the problem and a decision was reached to return. The remainder of the instruments seemed normal and since I was not sure what had caused the anomaly; we elected to return immediately. Landing weight was checked on final at 210;000 LBS and an uneventful landing was accomplished. After shutdown; a Maintenance Supervisor advised us that the VMO/MMO switch was in the incorrect aux position rather than normal position. Although the position of the switch is not accessible by aircrew both the First Officer and I failed to note that the mach pointer was lower than normal during preflight. The pointer is not acutely lower than normal in this condition and in nearly 14 years on this airplane I have never seen this before. Although I checked the indicator I just did not notice the low mach pointer. I will certainly in the future pay particularly close attention to this detail.
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.