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An air carrier flight crew flying a twin engine turbojet climbed above their assigned altitude during a stormy and turbulent approach when the autoplt disconnected.
| Attributes | |
| ACN | 431800 |
| Time | |
| Date | 199903 |
| Day | Sun |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : phl.airport |
| State Reference | PA |
| Altitude | msl bound lower : 2000 msl bound upper : 7350 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Windshear Turbulence Thunderstorm Rain |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : phl.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | descent : intermediate altitude |
| Route In Use | arrival : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 100 flight time total : 9500 flight time type : 5000 |
| ASRS Report | 431800 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 100 flight time total : 5000 flight time type : 50 |
| ASRS Report | 431792 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance non adherence : far incursion : runway |
| Independent Detector | aircraft equipment : altitude alert other flight crewa |
| Resolutory Action | flight crew : returned to original clearance |
| Consequence | Other |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance Weather |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We had been holding at the bunts intersection on the bunts arrival into phl, holding for thunderstorms on the approach and reported moderate to severe turbulence on approach to runway 9L. Phl switched runways to runway 27R and the storms had moved away so we were vectored for approach into phl and told to descend to 7000 ft MSL from 11000 ft MSL (our holding altitude). We were deviating around some cells on headings from 120-150 degrees. As we descended, we were in light and moderate turbulence and moderate rain. I leveled off at 7000 ft MSL and somehow the altitude hold channel clicked off during the turbulence. The altitude alert went off at 7300 ft MSL and at 7350 ft MSL I descended back to 7000 ft MSL. Total deviation of 350 ft. We verified with the controller (after leveling at 7000 ft MSL) that we were level at 7000 ft MSL.
Original NASA ASRS Text
Title: AN ACR FLC FLYING A TWIN ENG TURBOJET CLBED ABOVE THEIR ASSIGNED ALT DURING A STORMY AND TURBULENT APCH WHEN THE AUTOPLT DISCONNECTED.
Narrative: WE HAD BEEN HOLDING AT THE BUNTS INTXN ON THE BUNTS ARR INTO PHL, HOLDING FOR TSTMS ON THE APCH AND RPTED MODERATE TO SEVERE TURB ON APCH TO RWY 9L. PHL SWITCHED RWYS TO RWY 27R AND THE STORMS HAD MOVED AWAY SO WE WERE VECTORED FOR APCH INTO PHL AND TOLD TO DSND TO 7000 FT MSL FROM 11000 FT MSL (OUR HOLDING ALT). WE WERE DEVIATING AROUND SOME CELLS ON HDGS FROM 120-150 DEGS. AS WE DSNDED, WE WERE IN LIGHT AND MODERATE TURB AND MODERATE RAIN. I LEVELED OFF AT 7000 FT MSL AND SOMEHOW THE ALT HOLD CHANNEL CLICKED OFF DURING THE TURB. THE ALT ALERT WENT OFF AT 7300 FT MSL AND AT 7350 FT MSL I DSNDED BACK TO 7000 FT MSL. TOTAL DEV OF 350 FT. WE VERIFIED WITH THE CTLR (AFTER LEVELING AT 7000 FT MSL) THAT WE WERE LEVEL AT 7000 FT MSL.
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.