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Flight crew of a DC8-63F overshot cruise altitude due to autoplt capturing a higher altitude than programmed.
| Attributes | |
| ACN | 452608 |
| Time | |
| Date | 199910 |
| Day | Thu |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| State Reference | NE |
| Altitude | msl bound lower : 35000 msl bound upper : 35300 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zmp.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | DC-8 63 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : commercial pilot : multi engine pilot : instrument pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 10000 flight time type : 3000 |
| ASRS Report | 452608 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : multi engine pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 50 flight time total : 2100 flight time type : 450 |
| ASRS Report | 452610 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued alert flight crew : returned to assigned altitude |
| Consequence | other |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance |
| Primary Problem | Aircraft |
| Air Traffic Incident | Pilot Deviation |
Narrative:
After leveloff at FL350 aircraft continued to climb +80 ft (FL350 +80 ft) and leveled. ATC called and asked if we were level at FL350. I responded that 'yes' we were level FL350 and that the autoplt had climbed us an additional 80 ft. ATC said that they were showing +300 ft. Although at +80 ft leveloff is within normal limits an ATC encoded readout of +300 ft as compared to an indicated altitude of +80 ft is not within limits. Autoplt was written up in aircraft logbook due to additional previously experienced problems and the altitude discrepancy was also written up in the aircraft logbook. Later in the flight (XA40Z) while indicating FL350 +40 ft a B767 above us reported that his TCASII was showing us at FL350 +300 ft (FL353) while ZDC (location dbl) was showing us FL350.
Original NASA ASRS Text
Title: FLC OF A DC8-63F OVERSHOT CRUISE ALT DUE TO AUTOPLT CAPTURING A HIGHER ALT THAN PROGRAMMED.
Narrative: AFTER LEVELOFF AT FL350 ACFT CONTINUED TO CLB +80 FT (FL350 +80 FT) AND LEVELED. ATC CALLED AND ASKED IF WE WERE LEVEL AT FL350. I RESPONDED THAT 'YES' WE WERE LEVEL FL350 AND THAT THE AUTOPLT HAD CLBED US AN ADDITIONAL 80 FT. ATC SAID THAT THEY WERE SHOWING +300 FT. ALTHOUGH AT +80 FT LEVELOFF IS WITHIN NORMAL LIMITS AN ATC ENCODED READOUT OF +300 FT AS COMPARED TO AN INDICATED ALT OF +80 FT IS NOT WITHIN LIMITS. AUTOPLT WAS WRITTEN UP IN ACFT LOGBOOK DUE TO ADDITIONAL PREVIOUSLY EXPERIENCED PROBS AND THE ALT DISCREPANCY WAS ALSO WRITTEN UP IN THE ACFT LOGBOOK. LATER IN THE FLT (XA40Z) WHILE INDICATING FL350 +40 FT A B767 ABOVE US RPTED THAT HIS TCASII WAS SHOWING US AT FL350 +300 FT (FL353) WHILE ZDC (LOCATION DBL) WAS SHOWING US FL350.
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.