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An md super 80 in cruise had the autoplt begin an uncommanded climb which resulted in an 800 ft altitude deviation. Altitude alerting also malfunctioned.
| Attributes | |
| ACN | 440026 |
| Time | |
| Date | 199906 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | navaid : air.vor |
| State Reference | OH |
| Altitude | msl bound lower : 33000 msl bound upper : 33800 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zlc.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | MD-80 Super 80 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other vortac |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 440026 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : multi engine pilot : instrument |
| ASRS Report | 440025 |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : published procedure non adherence : far |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | flight crew : returned to original clearance none taken : detected after the fact |
| Consequence | other |
| Factors | |
| Maintenance | performance deficiency : repair performance deficiency : testing performance deficiency : inspection |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
Level at FL330 in performance cruise mode, aircraft began an uncommanded climb. Autoplt was disconnected and climb was arrested at FL338. Began descent to FL330, ZOA notified of our altitude deviation. Engaged autoplt at FL330 in altitude hold mode. 30 seconds later, aircraft began a climb. Autoplt was disengaged before FL332 was exceeded.
Original NASA ASRS Text
Title: AN MD SUPER 80 IN CRUISE HAD THE AUTOPLT BEGIN AN UNCOMMANDED CLB WHICH RESULTED IN AN 800 FT ALTDEV. ALT ALERTING ALSO MALFUNCTIONED.
Narrative: LEVEL AT FL330 IN PERFORMANCE CRUISE MODE, ACFT BEGAN AN UNCOMMANDED CLB. AUTOPLT WAS DISCONNECTED AND CLB WAS ARRESTED AT FL338. BEGAN DSCNT TO FL330, ZOA NOTIFIED OF OUR ALTDEV. ENGAGED AUTOPLT AT FL330 IN ALT HOLD MODE. 30 SECONDS LATER, ACFT BEGAN A CLB. AUTOPLT WAS DISENGAGED BEFORE FL332 WAS EXCEEDED.
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.