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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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An air carrier flight crew in an large transport aircraft descended below their assigned altitude when they misunderstood their clearance.
| Attributes | |
| ACN | 397810 |
| Time | |
| Date | 199803 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : pvd |
| State Reference | RI |
| Altitude | msl bound lower : 10000 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zbw |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | 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 : commercial pilot : instrument |
| Experience | flight time last 90 days : 170 flight time total : 17000 flight time type : 1500 |
| ASRS Report | 397810 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | other pilot : cfi pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 150 flight time total : 12000 flight time type : 4000 |
| ASRS Report | 397812 |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : published procedure non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We had previously programmed the FMC for the norwich 2 arrival, crossing pvd at 11000 ft and 250 KTS. Upon receiving our clearance we copied 10000 ft and put this in the 'altitude window,' then both pointed to it and commented that no speed restr had been assigned. We had selected the flight level mode for the descent and leveled at 10000 ft a few mi prior to pvd. The controller caught our error and informed us we were assigned 11000 ft at pvd. We climbed back to our assigned altitude. Apparently we had both heard incorrectly or did not copy what we heard/read back. More disturbing is the fact we had both flown this arrival numerous times and knew the pvd altitude was 11000 ft. Had we returned to the vertical navigation mode of the FMC, we would have seen pvd at 11000 ft. Any time you believe you have been assigned an altitude different from the STAR or SID, it would be wise to confirm it with the controller.
Original NASA ASRS Text
Title: AN ACR FLC IN AN LGT ACFT DSNDED BELOW THEIR ASSIGNED ALT WHEN THEY MISUNDERSTOOD THEIR CLRNC.
Narrative: WE HAD PREVIOUSLY PROGRAMMED THE FMC FOR THE NORWICH 2 ARR, XING PVD AT 11000 FT AND 250 KTS. UPON RECEIVING OUR CLRNC WE COPIED 10000 FT AND PUT THIS IN THE 'ALT WINDOW,' THEN BOTH POINTED TO IT AND COMMENTED THAT NO SPD RESTR HAD BEEN ASSIGNED. WE HAD SELECTED THE FLT LEVEL MODE FOR THE DSCNT AND LEVELED AT 10000 FT A FEW MI PRIOR TO PVD. THE CTLR CAUGHT OUR ERROR AND INFORMED US WE WERE ASSIGNED 11000 FT AT PVD. WE CLBED BACK TO OUR ASSIGNED ALT. APPARENTLY WE HAD BOTH HEARD INCORRECTLY OR DID NOT COPY WHAT WE HEARD/READ BACK. MORE DISTURBING IS THE FACT WE HAD BOTH FLOWN THIS ARR NUMEROUS TIMES AND KNEW THE PVD ALT WAS 11000 FT. HAD WE RETURNED TO THE VERT NAV MODE OF THE FMC, WE WOULD HAVE SEEN PVD AT 11000 FT. ANY TIME YOU BELIEVE YOU HAVE BEEN ASSIGNED AN ALT DIFFERENT FROM THE STAR OR SID, IT WOULD BE WISE TO CONFIRM IT WITH THE CTLR.
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.