 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
An air carrier DC10 flight crew descended below their assigned altitude when the autoplt changed modes during the altitude capture phase of the leveloff.
| Attributes | |
| ACN | 390379 |
| Time | |
| Date | 199801 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : lev |
| State Reference | LA |
| Altitude | msl bound lower : 32600 msl bound upper : 33000 |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zhu |
| Operator | common carrier : air carrier |
| Make Model Name | DC-10 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 390379 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| ASRS Report | 390380 |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : overshoot inflight encounter other non adherence : clearance non adherence : far 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 |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
Altitude deviation leveling at FL330. Altitude was armed at FL340. Aircraft descended through FL330 to FL326. Altitude was not armed at FL328 where we first noticed deviation. Supplemental information from acn 390380: altitude deviation leveling at FL330. Descending from FL370 due moderate turbulence. Encountered continuing, though diminished, turbulence approaching leveloff at FL330. Autoplt went to capture mode then, or some reason, reverted to vertical speed mode before reaching FL330. Caught deviation passing FL328. Captain (PF) disconnected autoplt and recovered expeditiously to FL330. Informed ATC of continued turbulence per their inquiry. ATC said nothing about our minimum altitude of FL326.
Original NASA ASRS Text
Title: AN ACR DC10 FLC DSNDED BELOW THEIR ASSIGNED ALT WHEN THE AUTOPLT CHANGED MODES DURING THE ALT CAPTURE PHASE OF THE LEVELOFF.
Narrative: ALTDEV LEVELING AT FL330. ALT WAS ARMED AT FL340. ACFT DSNDED THROUGH FL330 TO FL326. ALT WAS NOT ARMED AT FL328 WHERE WE FIRST NOTICED DEV. SUPPLEMENTAL INFO FROM ACN 390380: ALTDEV LEVELING AT FL330. DSNDING FROM FL370 DUE MODERATE TURB. ENCOUNTERED CONTINUING, THOUGH DIMINISHED, TURB APCHING LEVELOFF AT FL330. AUTOPLT WENT TO CAPTURE MODE THEN, OR SOME REASON, REVERTED TO VERT SPD MODE BEFORE REACHING FL330. CAUGHT DEV PASSING FL328. CAPT (PF) DISCONNECTED AUTOPLT AND RECOVERED EXPEDITIOUSLY TO FL330. INFORMED ATC OF CONTINUED TURB PER THEIR INQUIRY. ATC SAID NOTHING ABOUT OUR MINIMUM ALT OF FL326.
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.