B732 FLC ARE ALERTED BY N90 OF HDG DISCREPANCY. DURING TROUBLESHOOTING; FO ALLOWS ACFT TO OVERSHOOT ALT.

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WE WERE DEPARTING ON RWY 31 IN LGA WITH AN ASSIGNMENT TO TURN TO 350 DEG HDG AFTER TKOF. I HAD FLOWN THE AIRPLANE INTO LGA AND THE FO WAS FLYING THE OUTBOUND LEG. AS WE TURNED ONTO THE RWY FOR DEP; WE DID NOT NOTICE AN APPROX 30 DEG HDG ERROR IN OUR COMPASS SYS. AT 400 FT; I CALLED THE ALT SO THAT THE FO WOULD START A R TURN TO THE 350 DEG HDG. AS HE STARTED THE TURN; WE WERE GIVEN A FREQ CHANGE. I LOOKED DOWN TO CHANGE THE FREQ AND CHKED IN WITH APCH CTL. WHEN I LOOKED BACK AT THE HSI; WE WERE ON A 350 DEG HDG. I THOUGHT THAT WE HAD COMPLETED THE TURN QUICKLY; BUT DID NOT SUSPECT A PROB BECAUSE EVERYTHING HAD WORKED NORMALLY ON THE LEG BEFORE. WE WERE ACTUALLY FLYING A 320-325 DEG HDG. SHORTLY AFTER I CHKED IN WITH NEW YORK APCH; WE WERE GIVEN A HDG TO FLY TO SBJ VOR. AFTER A COUPLE OF MINS; APCH ASKED OUR HDG AND IF WE WERE GOING DIRECT TO SBJ. I BEGAN TO SUSPECT A PROB WITH THE COMPASS SYS AT THAT TIME. I INFORMED APCH THAT WE HAD A PROB AND I BEGAN TO TROUBLESHOOT WHILE THE FO WAS HAND FLYING THE ACFT. WE WERE NOW AT 17000 FT MSL. AFTER SWITCHING BTWN OUR 2 COMPASS SYS; THE PROB STILL EXISTED; SO I SWITCHED TO THE DIRECTIONAL GYRO MODE AND MANUALLY SLAVED THE COMPASS TO THE WET COMPASS HDG. WHILE I WAS INVOLVED WITH THE TROUBLESHOOTING; THE FO HAD INADVERTENTLY ALLOWED THE AIRPLANE TO CLB TO 17300 FT. DEP CTL ASKED US TO CHK THE ALT AND THE FO IMMEDIATELY CORRECTED TO 17000 FT. AFTER THE COMPASS WAS SLAVED TO THE CORRECT HDG; WE WERE ABLE TO NAV TO TPA WITHOUT ANY FURTHER PROBS. HUMAN PERFORMANCE CONSIDERATIONS: THE PROBS THAT WE HAD ONCE AIRBORNE WERE REALLY CAUSED FROM NOT PAYING CLOSE ENOUGH ATTN TO THE COMPASS SYS ON THE GND; WHEN TURNING ONTO THE RWY. WE HAD GONE ON DUTY THAT DAY AT YY15 AND SHOULD HAVE BEEN LNDG IN TPA AT XA30; BUT WE HAD BEEN DELAYED EARLIER AND WERE JUST GETTING AIRBORNE AT JA00. LGA WAS NOT BUSY AT JA00; SO THAT WE WERE GIVEN AN IMMEDIATE CLRNC FOR TKOF. AS WE TURNED ON THE RWY; I THINK I WAS MORE INVOLVED WITH ALIGNING THE AIRPLANE ON THE CTRLINE AND XFERRING CTL OF THE ACFT TO THE FO THAN CHKING THE ALIGNMENT OF THE COMPASS. I THINK THAT FATIGUE PLAYED A ROLE AS WELL. I HAD AWOKE AT XX00 TO COMMUTE OVER FOR MY TRIP. THE FO LIVES IN THE LCL AREA; BUT ALSO HAD ARISEN EARLY. AT THE TIME OF TKOF; I HAD BEEN AWAKE FOR 17 HRS. WHILE I FELT FINE; IT IS NECESSARY TO BE MORE VIGILANT AFTER BEING AWAKE FOR SO LONG. WE WERE ALSO LATE; SO WE WERE TRYING TO GET UNDERWAY AS QUICKLY AS POSSIBLE TO MAKE UP SOME OF THE TIME. AGAIN; IT IS IMPORTANT TO BE EXTRA VIGILANT UNDER THOSE CIRCUMSTANCES. AS FOR THE FO GETTING OFF THE ASSIGNED ALT; IT IS EXTREMELY IMPORTANT FOR THE PF TO FLY THE ACFT WHILE THE PNF TROUBLESHOOTS ANY PROBS. WHEN WE ARRIVED IN TPA; I WROTE UP THE COMPASS DISCREPANCY IN THE ACFT LOGBOOK. WHEN WE FLEW THE SAME ACFT LATER IN THE TRIP; I LEARNED THAT MAINT HAD FOUND THAT EVEN THOUGH THE FO'S COMPASS HAD FAILED IN THE NORMAL MODE; HIS FLAG WAS FROZEN OUT OF VIEW.