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An air carrier flight crew accepted a clearance for another air carrier with similar numerics. Other air carrier intervened. TCASII RA received in aircraft beginning unauthorized descent. Clearance reply to wrong call sign. Altitude deviation altitude excursion.
| Attributes | |
| ACN | 322511 |
| Time | |
| Date | 199511 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : eca |
| State Reference | CA |
| Altitude | msl bound lower : 27500 msl bound upper : 28000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| 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 | enroute airway : zoa |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time total : 4360 flight time type : 2081 |
| ASRS Report | 322511 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 8000 flight time type : 1500 |
| ASRS Report | 322025 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa other other : unspecified |
| Resolutory Action | flight crew : returned to intended course or assigned course other |
| Consequence | Other |
| Miss Distance | horizontal : 18000 vertical : 700 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
We were air carrier xyz. We had been cleared from FL290 to FL280 with a request for lower. ZOA cleared air carrier wxyz to FL240. Both the captain and I thought it was our clearance. He answered 'air carrier xyz leaving FL280 for FL240.' as we began descent, TCASII issued traffic alert. I leveled off at the direction of the captain while he contacted ATC. Before he could call, TCASII gave a RA climb command. We initiated climb back to FL280. Controller said descent was for air carrier wxyz, not air carrier xyz. Controller said separation was 700 ft vertical and 3 mi horizontal. Contributing factors were: busy ATC frequency, similar ending call signs, and controller not hearing erroneous callback. TCASII did a good job of keeping the aircraft from losing additional separation. Supplemental information from acn 322025: contributing factors: fatigue of crew in 11TH duty hour completing 9TH hour of flight, due to heavy headwinds. Controller not hearing erroneous readback. Controller told of my error by other air carrier that 'someone else had answered.'
Original NASA ASRS Text
Title: AN ACR FLC ACCEPTED A CLRNC FOR ANOTHER ACR WITH SIMILAR NUMERICS. OTHER ACR INTERVENED. TCASII RA RECEIVED IN ACFT BEGINNING UNAUTH DSCNT. CLRNC REPLY TO WRONG CALL SIGN. ALTDEV ALT EXCURSION.
Narrative: WE WERE ACR XYZ. WE HAD BEEN CLRED FROM FL290 TO FL280 WITH A REQUEST FOR LOWER. ZOA CLRED ACR WXYZ TO FL240. BOTH THE CAPT AND I THOUGHT IT WAS OUR CLRNC. HE ANSWERED 'ACR XYZ LEAVING FL280 FOR FL240.' AS WE BEGAN DSCNT, TCASII ISSUED TFC ALERT. I LEVELED OFF AT THE DIRECTION OF THE CAPT WHILE HE CONTACTED ATC. BEFORE HE COULD CALL, TCASII GAVE A RA CLB COMMAND. WE INITIATED CLB BACK TO FL280. CTLR SAID DSCNT WAS FOR ACR WXYZ, NOT ACR XYZ. CTLR SAID SEPARATION WAS 700 FT VERT AND 3 MI HORIZ. CONTRIBUTING FACTORS WERE: BUSY ATC FREQ, SIMILAR ENDING CALL SIGNS, AND CTLR NOT HEARING ERRONEOUS CALLBACK. TCASII DID A GOOD JOB OF KEEPING THE ACFT FROM LOSING ADDITIONAL SEPARATION. SUPPLEMENTAL INFO FROM ACN 322025: CONTRIBUTING FACTORS: FATIGUE OF CREW IN 11TH DUTY HR COMPLETING 9TH HR OF FLT, DUE TO HVY HEADWINDS. CTLR NOT HEARING ERRONEOUS READBACK. CTLR TOLD OF MY ERROR BY OTHER ACR THAT 'SOMEONE ELSE HAD ANSWERED.'
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.