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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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A DC9 was descended 800 ft below its assigned altitude. The flight crew had mistaken a clearance for another company airplane (similar flight number) as their clearance to descend. The center controller intervened.
| Attributes | |
| ACN | 350890 |
| Time | |
| Date | 199610 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : clt |
| State Reference | NC |
| Altitude | msl bound lower : 14200 msl bound upper : 15000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : ztl |
| Operator | common carrier : air carrier |
| Make Model Name | DC-9 30 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 250 flight time total : 11000 flight time type : 3000 |
| ASRS Report | 350890 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 210 flight time total : 14000 flight time type : 4000 |
| ASRS Report | 350466 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Our aircraft was level at 15000 ft when center cleared us to amend altitude to 13000 ft. We read back the clearance to 13000 ft and began descent. At 14200 ft center asked us to maintain 15000 ft. We responded that we had been previously cleared to 13000 ft and that we would return to 15000 ft. Center said we had not been cleared to 13000 ft and told us 'just to level off at 14000 ft.' there were 2 company planes on the frequency with similar numbers (xabd ours, and xabb).' I believe center mistakenly gave us the 13000 ft clearance instead of xabb. As a side note, on the following flight from clt to rdu, we were still flight xabd and company xbbd was on the same frequency. The similar call sign issue is a continuing problem that needs to be avoided.
Original NASA ASRS Text
Title: A DC9 WAS DSNDED 800 FT BELOW ITS ASSIGNED ALT. THE FLC HAD MISTAKEN A CLRNC FOR ANOTHER COMPANY AIRPLANE (SIMILAR FLT NUMBER) AS THEIR CLRNC TO DSND. THE CTR CTLR INTERVENED.
Narrative: OUR ACFT WAS LEVEL AT 15000 FT WHEN CTR CLRED US TO AMEND ALT TO 13000 FT. WE READ BACK THE CLRNC TO 13000 FT AND BEGAN DSCNT. AT 14200 FT CTR ASKED US TO MAINTAIN 15000 FT. WE RESPONDED THAT WE HAD BEEN PREVIOUSLY CLRED TO 13000 FT AND THAT WE WOULD RETURN TO 15000 FT. CTR SAID WE HAD NOT BEEN CLRED TO 13000 FT AND TOLD US 'JUST TO LEVEL OFF AT 14000 FT.' THERE WERE 2 COMPANY PLANES ON THE FREQ WITH SIMILAR NUMBERS (XABD OURS, AND XABB).' I BELIEVE CTR MISTAKENLY GAVE US THE 13000 FT CLRNC INSTEAD OF XABB. AS A SIDE NOTE, ON THE FOLLOWING FLT FROM CLT TO RDU, WE WERE STILL FLT XABD AND COMPANY XBBD WAS ON THE SAME FREQ. THE SIMILAR CALL SIGN ISSUE IS A CONTINUING PROB THAT NEEDS TO BE AVOIDED.
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.