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Air carrier medium large transport aircraft deviated from assigned altitude when a malfunction of the aircraft autoplt caused the aircraft to descend when the heading select was activated.
| Attributes | |
| ACN | 225033 |
| Time | |
| Date | 199210 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | airport : dfw |
| State Reference | TX |
| Altitude | msl bound lower : 10700 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | cruise other descent other |
| Route In Use | arrival other arrival star : star enroute airway : dfw |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 70 flight time total : 6000 flight time type : 500 |
| ASRS Report | 225033 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course flight crew : overcame equipment problem |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
During approach in VNAV/navigation level at 11000 with 11000 ft in altitude select window, aircraft began a rapid unscheduled descent when heading select was activated. Crew began an immediate climb back to 11000 resulting in a 300 ft deviation. A TCASII RA 'climb' alert was received momentarily. No further conflict was noted.
Original NASA ASRS Text
Title: ACR MLG ACFT DEVIATED FROM ASSIGNED ALT WHEN A MALFUNCTION OF THE ACFT AUTOPLT CAUSED THE ACFT TO DSND WHEN THE HDG SELECT WAS ACTIVATED.
Narrative: DURING APCH IN VNAV/NAV LEVEL AT 11000 WITH 11000 FT IN ALT SELECT WINDOW, ACFT BEGAN A RAPID UNSCHEDULED DSCNT WHEN HDG SELECT WAS ACTIVATED. CREW BEGAN AN IMMEDIATE CLB BACK TO 11000 RESULTING IN A 300 FT DEV. A TCASII RA 'CLB' ALERT WAS RECEIVED MOMENTARILY. NO FURTHER CONFLICT WAS NOTED.
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.