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Captain of a super MD80 descended below assigned altitude during descent due to an autoplt altitude capture problem. He returned aircraft to assigned altitude and then caught error before the aircraft passed leveloff altitude during subsequent dscnts.
| Attributes | |
| ACN | 391328 |
| Time | |
| Date | 199801 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : sbq |
| State Reference | FL |
| Altitude | msl bound lower : 19600 msl bound upper : 20000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Night |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | MD-80 Series (DC-9-80) Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | descent other |
| Route In Use | arrival star : star enroute airway : j41 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 225 flight time total : 22000 flight time type : 2600 |
| ASRS Report | 391328 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 100 flight time total : 10000 flight time type : 100 |
| ASRS Report | 391860 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Flying on #2 autoplt, was given clearance to descend to FL200 during approach to rsw. Altitude was set and armed. Approaching leveloff, amber altitude light on FMA went out but autoplt failed to capture altitude. Aircraft noted passing through FL200 vertical speed wheel was rolled up and altitude hold selected. Aircraft stopped descent 400 ft below FL200. Vertical speed climb and FL200 reselected. Before reaching FL200 center issued clearance to 13000 ft. Same occurrence with autoplt leveloff at 13000 ft and subsequent 11000 ft clearance. However, closer monitoring prevented altitude deviation. Two other autoplt malfunctions during flight, related to turns. Autoflt write- up made at flight termination.
Original NASA ASRS Text
Title: CAPT OF A SUPER MD80 DSNDED BELOW ASSIGNED ALT DURING DSCNT DUE TO AN AUTOPLT ALT CAPTURE PROB. HE RETURNED ACFT TO ASSIGNED ALT AND THEN CAUGHT ERROR BEFORE THE ACFT PASSED LEVELOFF ALT DURING SUBSEQUENT DSCNTS.
Narrative: FLYING ON #2 AUTOPLT, WAS GIVEN CLRNC TO DSND TO FL200 DURING APCH TO RSW. ALT WAS SET AND ARMED. APCHING LEVELOFF, AMBER ALT LIGHT ON FMA WENT OUT BUT AUTOPLT FAILED TO CAPTURE ALT. ACFT NOTED PASSING THROUGH FL200 VERT SPD WHEEL WAS ROLLED UP AND ALT HOLD SELECTED. ACFT STOPPED DSCNT 400 FT BELOW FL200. VERT SPD CLB AND FL200 RESELECTED. BEFORE REACHING FL200 CTR ISSUED CLRNC TO 13000 FT. SAME OCCURRENCE WITH AUTOPLT LEVELOFF AT 13000 FT AND SUBSEQUENT 11000 FT CLRNC. HOWEVER, CLOSER MONITORING PREVENTED ALTDEV. TWO OTHER AUTOPLT MALFUNCTIONS DURING FLT, RELATED TO TURNS. AUTOFLT WRITE- UP MADE AT FLT TERMINATION.
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.