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An md-82 flight crew diverted to the nearest suitable airport in response to unreliable airspeed/mach indications on both pilots' flight instruments.
| Attributes | |
| ACN | 1080315 |
| Time | |
| Date | 201304 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | MD-82 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Airspeed Indicator |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Total 16000 |
| Person 2 | |
| Function | Pilot Not Flying First Officer |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
We declared and emergency and diverted uneventfully to the nearest suitable airport due to unreliable airspeed indications at FL330. Conditions at the time were daylight VFR. The captain was flying and the first officer pilot not flying. The first indication of a problem was the auto throttle disconnecting followed by an autopilot disconnect. The mach trim light also annunciated on the overhead panel. There were no other failure indications. We moved the digital flight guidance system (DFGS) switch to the first officer's side in an attempt to reengage the autothrottle and autopilot but they would not engage. In reviewing the mach trim light abnormal; it became evident that there was a discrepancy between the captain and first officer's indicated airspeeds and mach numbers. The captain's indicated approximately .75M and 270 KTS and the first officer's .79M and 280 KTS. While running the unreliable airspeed indication abnormal checklist it became evident that neither the captain's nor the first officer's airspeed and mach indicators were responding properly to adjustments in power settings. The standby airspeed indicator seemed to be the only reliable indicator. Flying reverted to pitch and power settings from the checklist with a standby airspeed indicator crosscheck.
Original NASA ASRS Text
Title: An MD-82 flight crew diverted to the nearest suitable airport in response to unreliable airspeed/mach indications on both pilots' flight instruments.
Narrative: We declared and emergency and diverted uneventfully to the nearest suitable airport due to unreliable airspeed indications at FL330. Conditions at the time were daylight VFR. The Captain was flying and the First Officer pilot not flying. The first indication of a problem was the auto throttle disconnecting followed by an autopilot disconnect. The mach trim light also annunciated on the overhead panel. There were no other failure indications. We moved the Digital Flight Guidance System (DFGS) switch to the First Officer's side in an attempt to reengage the autothrottle and autopilot but they would not engage. In reviewing the Mach Trim Light abnormal; it became evident that there was a discrepancy between the Captain and First Officer's indicated airspeeds and Mach numbers. The Captain's indicated approximately .75M and 270 KTS and the First Officer's .79M and 280 KTS. While running the Unreliable Airspeed Indication Abnormal Checklist it became evident that neither the Captain's nor the First Officer's airspeed and mach indicators were responding properly to adjustments in power settings. The standby airspeed indicator seemed to be the only reliable indicator. Flying reverted to pitch and power settings from the checklist with a standby airspeed indicator crosscheck.
Data retrieved from NASA's ASRS site as of July 2013 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.