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Pilot lead of flight of two military fighters reports miscommunication and assumptions that lead to descent from assigned altitude in ZLA airspace.
| Attributes | |
| ACN | 813049 |
| Time | |
| Date | 200811 |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : zla.artcc |
| State Reference | CA |
| Altitude | msl single value : 27000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zla.artcc |
| Operator | other |
| Make Model Name | Fighter |
| Operating Under FAR Part | Part 91 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : military |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : military pilot : multi engine |
| Experience | flight time last 90 days : 60 flight time total : 2400 flight time type : 900 |
| ASRS Report | 813049 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance none taken : detected after the fact |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
Narrative:
Flight of 2; was returning after completing training. The lead pilot was communicating on the auxiliary radio with the student wingman and the lead WX systems officer was familiarizing himself with the 'atflir' on board the aircraft. The lead WX systems officer reported to the pilot 'bingo down to four O.' indicating that he was moving the low fuel indicator from 5000 pounds down to 4000 pounds. The pilot thought the WX systems officer said 'cleared down 240;' and assumed that he had missed center's call while talking on the auxiliary radio and that center had directed the aircraft to descend from FL270 to FL240. The WX systems officer in the lead aircraft continued to operate the 'atflir' and did not notice the aircraft was in a descent; the student in the wing aircraft assumed he had also missed center's call. The next call received was from ZLA directing flight to leveloff at FL250. At that point the aircraft had been in a descent for approximately 60 seconds and was passing through FL251. ZLA asked if we had heard a clearance to descend and lead WX systems officer responded 'negative.' at this point the crew idented the miscom and reported to center that the pilot had thought the flight had been cleared for the descent. Too many assumptions contrary to basic flight discipline and the 'swiss cheese' model led to this error. Numerous thousand ft climbs on the way to the area caused the pilot to assume the aircraft would be stepped down in a similar manner on the return. The WX systems officer assuming he did not need to monitor aircraft flight parameters caused him to miss the fact the aircraft was descending. The lead and student pilot assuming they had missed a call on the primary radio caused neither to question the descent. Finally; the lead pilot's failure to 'roger up' the WX systems officer statement caused the WX systems officer to assume the pilot heard him accurately.
Original NASA ASRS Text
Title: PILOT LEAD OF FLIGHT OF TWO MILITARY FIGHTERS REPORTS MISCOMMUNICATION AND ASSUMPTIONS THAT LEAD TO DESCENT FROM ASSIGNED ALTITUDE IN ZLA AIRSPACE.
Narrative: FLT OF 2; WAS RETURNING AFTER COMPLETING TRAINING. THE LEAD PLT WAS COMMUNICATING ON THE AUX RADIO WITH THE STUDENT WINGMAN AND THE LEAD WX SYSTEMS OFFICER WAS FAMILIARIZING HIMSELF WITH THE 'ATFLIR' ON BOARD THE ACFT. THE LEAD WX SYSTEMS OFFICER RPTED TO THE PLT 'BINGO DOWN TO FOUR O.' INDICATING THAT HE WAS MOVING THE LOW FUEL INDICATOR FROM 5000 LBS DOWN TO 4000 LBS. THE PLT THOUGHT THE WX SYSTEMS OFFICER SAID 'CLRED DOWN 240;' AND ASSUMED THAT HE HAD MISSED CTR'S CALL WHILE TALKING ON THE AUX RADIO AND THAT CTR HAD DIRECTED THE ACFT TO DSND FROM FL270 TO FL240. THE WX SYSTEMS OFFICER IN THE LEAD ACFT CONTINUED TO OPERATE THE 'ATFLIR' AND DID NOT NOTICE THE ACFT WAS IN A DSCNT; THE STUDENT IN THE WING ACFT ASSUMED HE HAD ALSO MISSED CTR'S CALL. THE NEXT CALL RECEIVED WAS FROM ZLA DIRECTING FLT TO LEVELOFF AT FL250. AT THAT POINT THE ACFT HAD BEEN IN A DSCNT FOR APPROX 60 SECONDS AND WAS PASSING THROUGH FL251. ZLA ASKED IF WE HAD HEARD A CLRNC TO DSND AND LEAD WX SYSTEMS OFFICER RESPONDED 'NEGATIVE.' AT THIS POINT THE CREW IDENTED THE MISCOM AND RPTED TO CTR THAT THE PLT HAD THOUGHT THE FLT HAD BEEN CLRED FOR THE DSCNT. TOO MANY ASSUMPTIONS CONTRARY TO BASIC FLT DISCIPLINE AND THE 'SWISS CHEESE' MODEL LED TO THIS ERROR. NUMEROUS THOUSAND FT CLBS ON THE WAY TO THE AREA CAUSED THE PLT TO ASSUME THE ACFT WOULD BE STEPPED DOWN IN A SIMILAR MANNER ON THE RETURN. THE WX SYSTEMS OFFICER ASSUMING HE DID NOT NEED TO MONITOR ACFT FLT PARAMETERS CAUSED HIM TO MISS THE FACT THE ACFT WAS DSNDING. THE LEAD AND STUDENT PLT ASSUMING THEY HAD MISSED A CALL ON THE PRIMARY RADIO CAUSED NEITHER TO QUESTION THE DSCNT. FINALLY; THE LEAD PLT'S FAILURE TO 'ROGER UP' THE WX SYSTEMS OFFICER STATEMENT CAUSED THE WX SYSTEMS OFFICER TO ASSUME THE PLT HEARD HIM ACCURATELY.
Data retrieved from NASA's ASRS site as of May 2009 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.