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Flight crew misunderstood descent clearance and descended into conflict with opposite direction traffic.
| Attributes | |
| ACN | 82425 |
| Time | |
| Date | 198802 |
| Day | Mon |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : air |
| State Reference | OH |
| Altitude | msl bound lower : 33000 msl bound upper : 34400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | climbout : intermediate altitude cruise other descent other |
| Route In Use | enroute airway : zob |
| Flight Plan | IFR |
| Aircraft 2 | |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 190 flight time total : 13100 flight time type : 760 |
| ASRS Report | 82425 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 145 flight time total : 6000 flight time type : 400 |
| ASRS Report | 82294 |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : required legal separation non adherence : clearance other anomaly other |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course none taken : insufficient time other |
| Consequence | faa : investigated faa : reviewed incident with flight crew |
| Miss Distance | horizontal : 15600 vertical : 1600 |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
Our flight was operating at FL370. Approximately air VOR the controller cleared us to, 'cross 50 mi from eey 270, cleared direct to eey, hurry to FL310, pilot discretion after that.' we were still quite a distance from that point, and a good distance from our start of descent point. The first officer, at my request, asked if we could just have pilot's discretion. The reply to the best of my knowledge was, 'hurry down to FL350 for now.' we complied. At FL350 we encountered light turbulence, but also noted an aircraft proceeding left to right directly under us. At what altitude we didn't know, but I guessed FL310 or FL330. At this time we still thought we were cleared pilot's discretion to FL270, and I commented to the first officer, 'I wonder if the controller knew about him (the other aircraft)?' we had been level at FL350 for no more than 2 mins, still encountering light turbulence, and after the other aircraft had passed, I started descent simultaneously advising the controller, 'large transport X is picking up light chop and is out of 350.' no traffic advisory was given of the other aircraft shortly thereafter we were cleared to descended. About 5 mins later we were advised we had an altitude excursion and if we desired further information, to call the watch supervisor cle ARTCC, which we did. The next day I also called the quality control officer who explained the situation to me. His only comment about the controller was, 'he could have used better phraseology,' but did say the tapes replayed said he told us to, 'hurry to FL350 now, lower later,' or words to that effect. We did not remember that. Both of us were sure hurry to 350 and pilot's discretion to 270 was our clearance. I was equally surprised when the aircraft passed under us and that it was at FL330. Had we started out of FL270 and hurried to FL310 as was our first instruction, I believe we would have been very close to that aircraft. I believe the real problem is that the controller had to have us at FL350 or lower to hand us off to the next sector whose boundary was approaching very rapidly, as we were still a long way from our top of descent point.
Original NASA ASRS Text
Title: FLT CREW MISUNDERSTOOD DESCENT CLRNC AND DESCENDED INTO CONFLICT WITH OPPOSITE DIRECTION TRAFFIC.
Narrative: OUR FLT WAS OPERATING AT FL370. APPROX AIR VOR THE CTLR CLRED US TO, 'CROSS 50 MI FROM EEY 270, CLRED DIRECT TO EEY, HURRY TO FL310, PLT DISCRETION AFTER THAT.' WE WERE STILL QUITE A DISTANCE FROM THAT POINT, AND A GOOD DISTANCE FROM OUR START OF DSCNT POINT. THE F/O, AT MY REQUEST, ASKED IF WE COULD JUST HAVE PLT'S DISCRETION. THE REPLY TO THE BEST OF MY KNOWLEDGE WAS, 'HURRY DOWN TO FL350 FOR NOW.' WE COMPLIED. AT FL350 WE ENCOUNTERED LIGHT TURB, BUT ALSO NOTED AN ACFT PROCEEDING LEFT TO RIGHT DIRECTLY UNDER US. AT WHAT ALT WE DIDN'T KNOW, BUT I GUESSED FL310 OR FL330. AT THIS TIME WE STILL THOUGHT WE WERE CLRED PLT'S DISCRETION TO FL270, AND I COMMENTED TO THE FO, 'I WONDER IF THE CTLR KNEW ABOUT HIM (THE OTHER ACFT)?' WE HAD BEEN LEVEL AT FL350 FOR NO MORE THAN 2 MINS, STILL ENCOUNTERING LIGHT TURB, AND AFTER THE OTHER ACFT HAD PASSED, I STARTED DSCNT SIMULTANEOUSLY ADVISING THE CTLR, 'LGT X IS PICKING UP LIGHT CHOP AND IS OUT OF 350.' NO TFC ADVISORY WAS GIVEN OF THE OTHER ACFT SHORTLY THEREAFTER WE WERE CLRED TO DESCENDED. ABOUT 5 MINS LATER WE WERE ADVISED WE HAD AN ALT EXCURSION AND IF WE DESIRED FURTHER INFO, TO CALL THE WATCH SUPVR CLE ARTCC, WHICH WE DID. THE NEXT DAY I ALSO CALLED THE QUALITY CTL OFFICER WHO EXPLAINED THE SITUATION TO ME. HIS ONLY COMMENT ABOUT THE CTLR WAS, 'HE COULD HAVE USED BETTER PHRASEOLOGY,' BUT DID SAY THE TAPES REPLAYED SAID HE TOLD US TO, 'HURRY TO FL350 NOW, LOWER LATER,' OR WORDS TO THAT EFFECT. WE DID NOT REMEMBER THAT. BOTH OF US WERE SURE HURRY TO 350 AND PLT'S DISCRETION TO 270 WAS OUR CLRNC. I WAS EQUALLY SURPRISED WHEN THE ACFT PASSED UNDER US AND THAT IT WAS AT FL330. HAD WE STARTED OUT OF FL270 AND HURRIED TO FL310 AS WAS OUR FIRST INSTRUCTION, I BELIEVE WE WOULD HAVE BEEN VERY CLOSE TO THAT ACFT. I BELIEVE THE REAL PROB IS THAT THE CTLR HAD TO HAVE US AT FL350 OR LOWER TO HAND US OFF TO THE NEXT SECTOR WHOSE BOUNDARY WAS APCHING VERY RAPIDLY, AS WE WERE STILL A LONG WAY FROM OUR TOP OF DSCNT POINT.
Data retrieved from NASA's ASRS site as of August 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.