Narrative:

While cruising at FL390 from sdf to bil, ZMP gave us a 15 degree heading change for traffic separation. Thinking I heard 'right,' I turned the heading selector 15 degrees right of our current heading. I had taken my headset off earlier to don the oxygen mask so the first officer could go to the john. I was listening to ATC with the cockpit speaker. The first officer acknowledged the heading change, but because I did not have my headset on, I could not hear his readback to ATC. In approximately 45 seconds, ATC came back with 'call sign, did you turn right?' without hesitating, the first officer responded, 'affirmative.' ATC then directed, 'well turn back to the left, quickly!' until I see the ATC tape transcript, I will not know what was said. The first officer did not correct me when I turned right, but he may have been distracted by an FMC message. He was changing speeds on the cruise page of the FMC because we were higher than our optimum altitude. Before center handed us off, he gave us a number to call at ZMP quality assurance. After landing, we called the number, and were told we were given a left turn, acknowledged a left turn, and turned right, missing the other aircraft by approximately 3 mi. The first officer may have been lax on checking me because, in his words, 'you're more careful than most other pilots.' I will start wearing my headset, even while wearing the oxygen mask. The sound quality from the cockpit speakers is not very good. If the controller said 'left,' I took it to mean 'right.' perhaps I'm predisposed to turn right. Also, I may not have read back the clearance 'cross-cockpit,' so the first officer could check my understanding.

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Original NASA ASRS Text

Title: CAPT RPTR TURNED WRONG WAY WHEN RECEIVING ATC HDG CHANGE. LACK OF CREW COORD IN FOLLOWING CLRNC. FLC ATC REVIEW.

Narrative: WHILE CRUISING AT FL390 FROM SDF TO BIL, ZMP GAVE US A 15 DEG HDG CHANGE FOR TFC SEPARATION. THINKING I HEARD 'R,' I TURNED THE HEADING SELECTOR 15 DEGS R OF OUR CURRENT HDG. I HAD TAKEN MY HEADSET OFF EARLIER TO DON THE OXYGEN MASK SO THE FO COULD GO TO THE JOHN. I WAS LISTENING TO ATC WITH THE COCKPIT SPEAKER. THE FO ACKNOWLEDGED THE HDG CHANGE, BUT BECAUSE I DID NOT HAVE MY HEADSET ON, I COULD NOT HEAR HIS READBACK TO ATC. IN APPROX 45 SECONDS, ATC CAME BACK WITH 'CALL SIGN, DID YOU TURN R?' WITHOUT HESITATING, THE FO RESPONDED, 'AFFIRMATIVE.' ATC THEN DIRECTED, 'WELL TURN BACK TO THE L, QUICKLY!' UNTIL I SEE THE ATC TAPE TRANSCRIPT, I WILL NOT KNOW WHAT WAS SAID. THE FO DID NOT CORRECT ME WHEN I TURNED R, BUT HE MAY HAVE BEEN DISTRACTED BY AN FMC MESSAGE. HE WAS CHANGING SPDS ON THE CRUISE PAGE OF THE FMC BECAUSE WE WERE HIGHER THAN OUR OPTIMUM ALT. BEFORE CTR HANDED US OFF, HE GAVE US A NUMBER TO CALL AT ZMP QUALITY ASSURANCE. AFTER LNDG, WE CALLED THE NUMBER, AND WERE TOLD WE WERE GIVEN A L TURN, ACKNOWLEDGED A L TURN, AND TURNED R, MISSING THE OTHER ACFT BY APPROX 3 MI. THE FO MAY HAVE BEEN LAX ON CHKING ME BECAUSE, IN HIS WORDS, 'YOU'RE MORE CAREFUL THAN MOST OTHER PLTS.' I WILL START WEARING MY HEADSET, EVEN WHILE WEARING THE OXYGEN MASK. THE SOUND QUALITY FROM THE COCKPIT SPEAKERS IS NOT VERY GOOD. IF THE CTLR SAID 'L,' I TOOK IT TO MEAN 'R.' PERHAPS I'M PREDISPOSED TO TURN R. ALSO, I MAY NOT HAVE READ BACK THE CLRNC 'CROSS-COCKPIT,' SO THE FO COULD CHK MY UNDERSTANDING.

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.