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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Large transport misunderstood clearance and descended below 10000 ft before the fix they were told to cross at 10000 ft. They thought they were cleared to descend at their discretion to 6000 ft.
| Attributes | |
| ACN | 356553 |
| Time | |
| Date | 199612 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : hli |
| State Reference | MS |
| Altitude | msl bound lower : 8000 msl bound upper : 10000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : mem tower : mci |
| Operator | common carrier : air carrier |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | cruise other descent other |
| Route In Use | arrival star : star |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : flight engineer pilot : commercial pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 9800 |
| ASRS Report | 356553 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : overshoot altitude deviation : crossing restriction not met non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Inbound to holly springs on holly 7 arrival to mem, was cleared to cross holly springs at 10000 ft. Thought I heard 'pilot's discretion descend and maintain 6000 ft.' captain read back, began descent. Going through 8000 ft controller said 'check altitude, should be at 10000 ft.' we replied that we understood discretion to 6000 ft but controller disagreed. We were reclred to 8000 ft with no problems. Fatigue was a factor in this incident, if we indeed misheard the cleared altitude. Trip began on xx dec at XA35, on duty flying till XJ00 am. Only able to get an hour sleep night before. On yy dec, were expected to sleep between XJ00 and next flight at XW25. Only got a few hours sleep. Went off duty at XB13 and back on duty at XJ00 next day. Only a few hours sleep. Back on duty at XJ00 am on zz dec. Incident occured about an hour later. Sleep deficit approximately 8 hours at time of incident.
Original NASA ASRS Text
Title: LGT MISUNDERSTOOD CLRNC AND DSNDED BELOW 10000 FT BEFORE THE FIX THEY WERE TOLD TO CROSS AT 10000 FT. THEY THOUGHT THEY WERE CLRED TO DSND AT THEIR DISCRETION TO 6000 FT.
Narrative: INBOUND TO HOLLY SPRINGS ON HOLLY 7 ARR TO MEM, WAS CLRED TO CROSS HOLLY SPRINGS AT 10000 FT. THOUGHT I HEARD 'PLT'S DISCRETION DSND AND MAINTAIN 6000 FT.' CAPT READ BACK, BEGAN DSCNT. GOING THROUGH 8000 FT CTLR SAID 'CHK ALT, SHOULD BE AT 10000 FT.' WE REPLIED THAT WE UNDERSTOOD DISCRETION TO 6000 FT BUT CTLR DISAGREED. WE WERE RECLRED TO 8000 FT WITH NO PROBS. FATIGUE WAS A FACTOR IN THIS INCIDENT, IF WE INDEED MISHEARD THE CLRED ALT. TRIP BEGAN ON XX DEC AT XA35, ON DUTY FLYING TILL XJ00 AM. ONLY ABLE TO GET AN HOUR SLEEP NIGHT BEFORE. ON YY DEC, WERE EXPECTED TO SLEEP BETWEEN XJ00 AND NEXT FLIGHT AT XW25. ONLY GOT A FEW HOURS SLEEP. WENT OFF DUTY AT XB13 AND BACK ON DUTY AT XJ00 NEXT DAY. ONLY A FEW HOURS SLEEP. BACK ON DUTY AT XJ00 AM ON ZZ DEC. INCIDENT OCCURED ABOUT AN HOUR LATER. SLEEP DEFICIT APPROX 8 HOURS AT TIME OF INCIDENT.
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.