Narrative:

After takeoff we started to clean up the aircraft. We were given a clearance to 'fly heading 120 degrees and climb and maintain 17000 ft MSL.' ATC gave us a frequency change and the PF called for flaps to 5 degrees. While I was complying with both, the captain was flying the aircraft, responding to what he described as unusual performance characteristics for our advertised weight. While our attention was diverted, the #1 compass precessed to about 70 degrees left. The captain started a slow left turn to maintain the assigned heading (not realizing the compass problem). As I looked at my HSI, I stated that my compass was in disagreement and we then checked the whiskey compass. At this time, ATC queried us and we announced that we had a compass problem and returned to an approximately southeast heading. We checked circuit breakers and reset our compasses (both). The problem was solved but not before deviating approximately 60 degrees from heading. I believe that minor changes in the normal departure and a 'heads down' situation for me (first officer) led to an inability to back up the PF with the use of correct heading indications. The captain's diversion of attention caused by better than anticipated performance was just enough to subdue his situational awareness allowing the malfunctioning compass to trick him into turning significantly away from the approximately runway heading. Also, a correct ATC clearance came right at a time where it seemed to corroborate a left turn direction. As a side note, both compasses were aligned with runway heading and both heading bugs were on the right heading. The malfunction occurred sometime after rotation.

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Original NASA ASRS Text

Title: A DISTR B727 PIC FOLLOWS HIS ERRANT #1 COMPASS AND TURNS AWAY FROM THE DEP HDG THAT WAS ASSIGNED BY DEP CTLR AT TUS, AZ.

Narrative: AFTER TKOF WE STARTED TO CLEAN UP THE ACFT. WE WERE GIVEN A CLRNC TO 'FLY HDG 120 DEGS AND CLB AND MAINTAIN 17000 FT MSL.' ATC GAVE US A FREQ CHANGE AND THE PF CALLED FOR FLAPS TO 5 DEGS. WHILE I WAS COMPLYING WITH BOTH, THE CAPT WAS FLYING THE ACFT, RESPONDING TO WHAT HE DESCRIBED AS UNUSUAL PERFORMANCE CHARACTERISTICS FOR OUR ADVERTISED WT. WHILE OUR ATTN WAS DIVERTED, THE #1 COMPASS PRECESSED TO ABOUT 70 DEGS L. THE CAPT STARTED A SLOW L TURN TO MAINTAIN THE ASSIGNED HDG (NOT REALIZING THE COMPASS PROB). AS I LOOKED AT MY HSI, I STATED THAT MY COMPASS WAS IN DISAGREEMENT AND WE THEN CHKED THE WHISKEY COMPASS. AT THIS TIME, ATC QUERIED US AND WE ANNOUNCED THAT WE HAD A COMPASS PROB AND RETURNED TO AN APPROX SE HDG. WE CHKED CIRCUIT BREAKERS AND RESET OUR COMPASSES (BOTH). THE PROB WAS SOLVED BUT NOT BEFORE DEVIATING APPROX 60 DEGS FROM HDG. I BELIEVE THAT MINOR CHANGES IN THE NORMAL DEP AND A 'HEADS DOWN' SIT FOR ME (FO) LED TO AN INABILITY TO BACK UP THE PF WITH THE USE OF CORRECT HDG INDICATIONS. THE CAPT'S DIVERSION OF ATTN CAUSED BY BETTER THAN ANTICIPATED PERFORMANCE WAS JUST ENOUGH TO SUBDUE HIS SITUATIONAL AWARENESS ALLOWING THE MALFUNCTIONING COMPASS TO TRICK HIM INTO TURNING SIGNIFICANTLY AWAY FROM THE APPROX RWY HDG. ALSO, A CORRECT ATC CLRNC CAME RIGHT AT A TIME WHERE IT SEEMED TO CORROBORATE A L TURN DIRECTION. AS A SIDE NOTE, BOTH COMPASSES WERE ALIGNED WITH RWY HDG AND BOTH HDG BUGS WERE ON THE R HDG. THE MALFUNCTION OCCURRED SOMETIME AFTER ROTATION.

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.