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Air carrier B727 flight crew are questioned by ATC about their altitude. Flight crew observes that autoplt altitude hold disengaged without aural warning. Aircraft returned to assigned altitude. Previous logbook entry found on altitude hold disengage.
| Attributes | |
| ACN | 410611 |
| Time | |
| Date | 199808 |
| Day | Mon |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : txo |
| State Reference | TX |
| Altitude | msl bound lower : 31000 msl bound upper : 31500 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zab tower : grb |
| Operator | common carrier : air carrier |
| Make Model Name | B727 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 410611 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : second officer |
| Qualification | pilot : atp pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 150 flight time total : 6000 flight time type : 4200 |
| ASRS Report | 410612 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude |
| Independent Detector | other controllera |
| Resolutory Action | flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | other |
Narrative:
During level cruise at FL310 autoplt altitude hold disengaged without warning and aircraft slowly climbed to FL315. ZAB controller asked what our altitude was and aircraft was returned to FL310. Previous logbook writeup had same occurrence 10 days earlier. Aircraft had been in level flight for 30 mins.
Original NASA ASRS Text
Title: ACR B727 FLC ARE QUESTIONED BY ATC ABOUT THEIR ALT. FLC OBSERVES THAT AUTOPLT ALT HOLD DISENGAGED WITHOUT AURAL WARNING. ACFT RETURNED TO ASSIGNED ALT. PREVIOUS LOGBOOK ENTRY FOUND ON ALT HOLD DISENGAGE.
Narrative: DURING LEVEL CRUISE AT FL310 AUTOPLT ALT HOLD DISENGAGED WITHOUT WARNING AND ACFT SLOWLY CLBED TO FL315. ZAB CTLR ASKED WHAT OUR ALT WAS AND ACFT WAS RETURNED TO FL310. PREVIOUS LOGBOOK WRITEUP HAD SAME OCCURRENCE 10 DAYS EARLIER. ACFT HAD BEEN IN LEVEL FLT FOR 30 MINS.
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.