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Pilot of small transport checking recent maintenance items descended below assigned altitude while on autoplt.
| Attributes | |
| ACN | 133799 |
| Time | |
| Date | 199001 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : olm |
| State Reference | WA |
| Altitude | msl bound lower : 1400 msl bound upper : 2000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : sea |
| Operator | general aviation : corporate |
| Make Model Name | Small Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | descent : approach |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : instrument pilot : commercial pilot : cfi |
| Experience | flight time last 90 days : 35 flight time total : 2100 flight time type : 30 |
| ASRS Report | 133799 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Events | |
| Anomaly | altitude deviation : overshoot |
| Independent Detector | other controllera other other : unspecified cockpit |
| Resolutory Action | flight crew : regained aircraft control |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Approximately 15 NM out from olympia airport, while being vectored for an approach, approach control gave us an altitude alert. Our assigned altitude was 2000'. Aircraft descended to approximately 1400' while on autoplt with altitude hold engaged. Pilot's attention was outside the aircraft looking for airport and traffic. After regaining assigned altitude it was discovered the trim disconnect was in the 'off' position and the autoplt would not hold altitude, even though it would couple up and capture the assigned altitude initially. The aircraft had come out of maintenance and pilot failed to use the full checklist and instead relied on an abbreviated list, normally used for quick turnarounds. The autoplt will accept altitude hold with the trim turned off. Also, the pilot was in error for not using the full checklist after maintenance.
Original NASA ASRS Text
Title: PLT OF SMT CHECKING RECENT MAINTENANCE ITEMS DESCENDED BELOW ASSIGNED ALT WHILE ON AUTOPLT.
Narrative: APPROX 15 NM OUT FROM OLYMPIA ARPT, WHILE BEING VECTORED FOR AN APCH, APCH CTL GAVE US AN ALT ALERT. OUR ASSIGNED ALT WAS 2000'. ACFT DSNDED TO APPROX 1400' WHILE ON AUTOPLT WITH ALT HOLD ENGAGED. PLT'S ATTN WAS OUTSIDE THE ACFT LOOKING FOR ARPT AND TFC. AFTER REGAINING ASSIGNED ALT IT WAS DISCOVERED THE TRIM DISCONNECT WAS IN THE 'OFF' POS AND THE AUTOPLT WOULD NOT HOLD ALT, EVEN THOUGH IT WOULD COUPLE UP AND CAPTURE THE ASSIGNED ALT INITIALLY. THE ACFT HAD COME OUT OF MAINT AND PLT FAILED TO USE THE FULL CHKLIST AND INSTEAD RELIED ON AN ABBREVIATED LIST, NORMALLY USED FOR QUICK TURNAROUNDS. THE AUTOPLT WILL ACCEPT ALT HOLD WITH THE TRIM TURNED OFF. ALSO, THE PLT WAS IN ERROR FOR NOT USING THE FULL CHKLIST AFTER MAINT.
Data retrieved from NASA's ASRS site as of July 2007 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.