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Flight crew alleges they overshot altitude because altitude alert did not sound at 11000' (assigned altitude) because MCP jumped down to 10000'.
| Attributes | |
| ACN | 173633 |
| Time | |
| Date | 199103 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | airport : bwi |
| State Reference | MD |
| Altitude | msl bound lower : 10000 msl bound upper : 10800 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : bwi |
| 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 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : instrument pilot : commercial |
| Experience | flight time last 90 days : 190 flight time total : 12700 |
| ASRS Report | 173633 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance |
| Independent Detector | other flight crewa |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
In descent on west minister arrival into bwi. Autoplt engaged on VNAV descent. Xed ruane at 11000'/250 KIAS with 11000' set on MCP. Copilot was flying the aircraft and began to program FMC after level off at 11000'. I was getting ATIS, and looked up at altimeter and recognized altitude passing 10800' and descending. MCP displayed 10000' but was not changed by either pilot. Reconfirmed assigned altitude by approach control and was informed that it was 11000', but 10000' was ok for now as airspace was clear. Both first officer and I are sure that MCP was not changed by either one of us and feel that this was an uncommanded MCP altitude change. Adding to the occurrence was the fact that PNF was off frequency getting ATIS when crossing clearance had to be acknowledged and set by PF. Standard altitude awareness procedures could not be followed. Also adding to this is the fact that bwi ATIS is unreadable until 60-70 NM from airport when arriving from the west. This too busy a phase of flight to be listening to ATIS.
Original NASA ASRS Text
Title: FLT CREW ALLEGES THEY OVERSHOT ALT BECAUSE ALT ALERT DID NOT SOUND AT 11000' (ASSIGNED ALT) BECAUSE MCP JUMPED DOWN TO 10000'.
Narrative: IN DSNT ON WEST MINISTER ARR INTO BWI. AUTOPLT ENGAGED ON VNAV DSNT. XED RUANE AT 11000'/250 KIAS WITH 11000' SET ON MCP. COPLT WAS FLYING THE ACFT AND BEGAN TO PROGRAM FMC AFTER LEVEL OFF AT 11000'. I WAS GETTING ATIS, AND LOOKED UP AT ALTIMETER AND RECOGNIZED ALT PASSING 10800' AND DSNDING. MCP DISPLAYED 10000' BUT WAS NOT CHANGED BY EITHER PLT. RECONFIRMED ASSIGNED ALT BY APCH CTL AND WAS INFORMED THAT IT WAS 11000', BUT 10000' WAS OK FOR NOW AS AIRSPACE WAS CLR. BOTH F/O AND I ARE SURE THAT MCP WAS NOT CHANGED BY EITHER ONE OF US AND FEEL THAT THIS WAS AN UNCOMMANDED MCP ALT CHANGE. ADDING TO THE OCCURRENCE WAS THE FACT THAT PNF WAS OFF FREQ GETTING ATIS WHEN XING CLRNC HAD TO BE ACKNOWLEDGED AND SET BY PF. STANDARD ALT AWARENESS PROCS COULD NOT BE FOLLOWED. ALSO ADDING TO THIS IS THE FACT THAT BWI ATIS IS UNREADABLE UNTIL 60-70 NM FROM ARPT WHEN ARRIVING FROM THE W. THIS TOO BUSY A PHASE OF FLT TO BE LISTENING TO ATIS.
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.