Narrative:

After departing abq on an IFR flight to den, departure control turned us over to ZAB. Our clearance had read to expect FL410 5 mins after departure, and when we were cleared by the center controller to maintain FL390, the copilot acknowledged the altitude while I was setting up the navigation course for direct the alamosa VOR (as part of our departure clearance). The center radio transmission was of rather poor quality, and there was quite a bit of talk on the frequency with other traffic. At the time of this climb clearance, our altitude was about FL220, and we continued the climb. As we were passing through about FL260, the controller called traffic at our 1 O'clock position headed westbound, range about 20 mi. We reported traffic beacon in sight, and as we were climbing, observed the traffic move to our 11 O'clock position, at possibly 8-10 mi range. As we were leaving FL310, the controller called and asked us to confirm our altitude. We reported leaving FL310 for FL290, at which time the controller told us we had only been cleared to FL290. I started an immediate descent while the copilot responded that we had heard FL390, and he had read back FL390. The controller again said that FL290 was our assigned altitude, but that we could not climb to FL410. A few mins later we were asked to call the quality assurance supervisor at ZAB. Upon arriving den, I did call the supervisor and he said he had just finished reviewing the tapes, and that we had been cleared to FL290. My copilot had read back FL390, and the controller hadn't caught it, nor had the other controller supervisor who was working that position. He also stated that there would be no enforcement action against us, but would be some form of action taken against the controller for missing the readback. He stated that we would hear nothing from either ATC center or the FAA. Needles to say, we did hear it as 'FL390,' and have not instituted more procedures to be very positively certain we have no further missed communications, especially where the radio contact as been poor or fuzzy, or hurried because of traffic on the frequency. Supplemental information from acn 174039: I (first officer) read back our call sign and 'FL390.' there was no further controller response. There was significant chatter on the frequency and reception was approximately 3 X 3. The controller responded that we were cleared to FL290 only. The captain immediately and aggressively began a descent to FL290. I questioned the controller once again whether he had cleared us to FL290 or FL390. He said FL290. I responded that we had, 'understood FL390 and read back FL390.' shortly thereafter, we were advised to contact a quality assurance supervisor at ZAB to discuss the incident. The remainder of the flight transpired west/O incident. At den the captain called supervisor and informed me that he, the supervisor, after having listened to the ATC tape several times, decided that we were in fact cleared only to FL290, but that tape clearly reflects our response to be, 'cleared to FL390.' to prevent this type of incident from happening in the future, I have decided that even greater annunciation of responses be used and to question ATC when not responded to in a full and expected response manner.

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Original NASA ASRS Text

Title: COPRP JET CLEARED TO CLIMB TO FL290. READ BACK FL390 WHICH CTLR DID NOT CORRECT. POTENTIAL CONFLICT.

Narrative: AFTER DEPARTING ABQ ON AN IFR FLT TO DEN, DEP CTL TURNED US OVER TO ZAB. OUR CLRNC HAD READ TO EXPECT FL410 5 MINS AFTER DEP, AND WHEN WE WERE CLRED BY THE CENTER CTLR TO MAINTAIN FL390, THE COPLT ACKNOWLEDGED THE ALT WHILE I WAS SETTING UP THE NAV COURSE FOR DIRECT THE ALAMOSA VOR (AS PART OF OUR DEP CLRNC). THE CENTER RADIO XMISSION WAS OF RATHER POOR QUALITY, AND THERE WAS QUITE A BIT OF TALK ON THE FREQ WITH OTHER TFC. AT THE TIME OF THIS CLB CLRNC, OUR ALT WAS ABOUT FL220, AND WE CONTINUED THE CLB. AS WE WERE PASSING THROUGH ABOUT FL260, THE CTLR CALLED TFC AT OUR 1 O'CLOCK POS HEADED WBND, RANGE ABOUT 20 MI. WE RPTED TFC BEACON IN SIGHT, AND AS WE WERE CLBING, OBSERVED THE TFC MOVE TO OUR 11 O'CLOCK POS, AT POSSIBLY 8-10 MI RANGE. AS WE WERE LEAVING FL310, THE CTLR CALLED AND ASKED US TO CONFIRM OUR ALT. WE RPTED LEAVING FL310 FOR FL290, AT WHICH TIME THE CTLR TOLD US WE HAD ONLY BEEN CLRED TO FL290. I STARTED AN IMMEDIATE DSNT WHILE THE COPLT RESPONDED THAT WE HAD HEARD FL390, AND HE HAD READ BACK FL390. THE CTLR AGAIN SAID THAT FL290 WAS OUR ASSIGNED ALT, BUT THAT WE COULD NOT CLB TO FL410. A FEW MINS LATER WE WERE ASKED TO CALL THE QUALITY ASSURANCE SUPVR AT ZAB. UPON ARRIVING DEN, I DID CALL THE SUPVR AND HE SAID HE HAD JUST FINISHED REVIEWING THE TAPES, AND THAT WE HAD BEEN CLRED TO FL290. MY COPLT HAD READ BACK FL390, AND THE CTLR HADN'T CAUGHT IT, NOR HAD THE OTHER CTLR SUPVR WHO WAS WORKING THAT POS. HE ALSO STATED THAT THERE WOULD BE NO ENFORCEMENT ACTION AGAINST US, BUT WOULD BE SOME FORM OF ACTION TAKEN AGAINST THE CTLR FOR MISSING THE READBACK. HE STATED THAT WE WOULD HEAR NOTHING FROM EITHER ATC CENTER OR THE FAA. NEEDLES TO SAY, WE DID HEAR IT AS 'FL390,' AND HAVE NOT INSTITUTED MORE PROCS TO BE VERY POSITIVELY CERTAIN WE HAVE NO FURTHER MISSED COMS, ESPECIALLY WHERE THE RADIO CONTACT AS BEEN POOR OR FUZZY, OR HURRIED BECAUSE OF TFC ON THE FREQ. SUPPLEMENTAL INFO FROM ACN 174039: I (F/O) READ BACK OUR CALL SIGN AND 'FL390.' THERE WAS NO FURTHER CTLR RESPONSE. THERE WAS SIGNIFICANT CHATTER ON THE FREQ AND RECEPTION WAS APPROX 3 X 3. THE CTLR RESPONDED THAT WE WERE CLRED TO FL290 ONLY. THE CAPT IMMEDIATELY AND AGGRESSIVELY BEGAN A DSNT TO FL290. I QUESTIONED THE CTLR ONCE AGAIN WHETHER HE HAD CLRED US TO FL290 OR FL390. HE SAID FL290. I RESPONDED THAT WE HAD, 'UNDERSTOOD FL390 AND READ BACK FL390.' SHORTLY THEREAFTER, WE WERE ADVISED TO CONTACT A QUALITY ASSURANCE SUPVR AT ZAB TO DISCUSS THE INCIDENT. THE REMAINDER OF THE FLT TRANSPIRED W/O INCIDENT. AT DEN THE CAPT CALLED SUPVR AND INFORMED ME THAT HE, THE SUPVR, AFTER HAVING LISTENED TO THE ATC TAPE SEVERAL TIMES, DECIDED THAT WE WERE IN FACT CLRED ONLY TO FL290, BUT THAT TAPE CLEARLY REFLECTS OUR RESPONSE TO BE, 'CLRED TO FL390.' TO PREVENT THIS TYPE OF INCIDENT FROM HAPPENING IN THE FUTURE, I HAVE DECIDED THAT EVEN GREATER ANNUNCIATION OF RESPONSES BE USED AND TO QUESTION ATC WHEN NOT RESPONDED TO IN A FULL AND EXPECTED RESPONSE MANNER.

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.