Narrative:

Myself (captain) in right seat (PNF). First officer in left seat (PF). The first officer was a CL60 type rated pilot with approximately 750 hours in CL601 type aircraft, 8500 total hours. The first officer was also a fill-in pilot that I have flown with before, but not in the past 4 months. After departing runway 28 at agc, I contacted pit departure control, reported we were with him on the runway heading. He acknowledged and told us to remain at 3000 ft and heading 280 degrees. At 3000 ft MSL I completed the after takeoff checklist and noticed a TCASII fail flag. The PF told me to tell departure control we were deviating to the left for WX. I looked up and saw he had turned the aircraft to a heading of 220 degrees. I asked departure control if we could maintain a heading of 220 degrees for WX. He responded we were in 'big trouble' and 'not to worry about the WX.' he told us to turn right to a heading of 280 degrees and that he had arriving aircraft to pit. He later came back, gave a climb and a direct route to a VOR and a frequency change. Contributing factors: rain, turbulence, TCASII failure, and not flying with the first officer for a few months. I should have been monitoring the aircraft while I was doing the after takeoff checklist and not been preoccupied with the TCASII failure. The first officer should have announced that he needed a turn to the left before or during the turn so I could have notified departure control sooner. The lack of communication between the first officer and myself was the biggest factor in this situation, if he had said he needed a turn to avoid WX, I know I would have stopped what I was doing (since it was not a safety of flight action) and requested a turn to avoid WX, which was a safety of flight action.

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Original NASA ASRS Text

Title: A CL60 CREW, DEPARTING AGC, TURNED 60 DEGS FROM ASSIGNED DIRECT HDG WITHOUT ATC APPROVAL, CITING WX AVOIDANCE THE REASON.

Narrative: MYSELF (CAPT) IN R SEAT (PNF). FO IN L SEAT (PF). THE FO WAS A CL60 TYPE RATED PLT WITH APPROX 750 HRS IN CL601 TYPE ACFT, 8500 TOTAL HRS. THE FO WAS ALSO A FILL-IN PLT THAT I HAVE FLOWN WITH BEFORE, BUT NOT IN THE PAST 4 MONTHS. AFTER DEPARTING RWY 28 AT AGC, I CONTACTED PIT DEP CTL, RPTED WE WERE WITH HIM ON THE RWY HDG. HE ACKNOWLEDGED AND TOLD US TO REMAIN AT 3000 FT AND HDG 280 DEGS. AT 3000 FT MSL I COMPLETED THE AFTER TKOF CHKLIST AND NOTICED A TCASII FAIL FLAG. THE PF TOLD ME TO TELL DEP CTL WE WERE DEVIATING TO THE L FOR WX. I LOOKED UP AND SAW HE HAD TURNED THE ACFT TO A HDG OF 220 DEGS. I ASKED DEP CTL IF WE COULD MAINTAIN A HDG OF 220 DEGS FOR WX. HE RESPONDED WE WERE IN 'BIG TROUBLE' AND 'NOT TO WORRY ABOUT THE WX.' HE TOLD US TO TURN R TO A HDG OF 280 DEGS AND THAT HE HAD ARRIVING ACFT TO PIT. HE LATER CAME BACK, GAVE A CLB AND A DIRECT RTE TO A VOR AND A FREQ CHANGE. CONTRIBUTING FACTORS: RAIN, TURB, TCASII FAILURE, AND NOT FLYING WITH THE FO FOR A FEW MONTHS. I SHOULD HAVE BEEN MONITORING THE ACFT WHILE I WAS DOING THE AFTER TKOF CHKLIST AND NOT BEEN PREOCCUPIED WITH THE TCASII FAILURE. THE FO SHOULD HAVE ANNOUNCED THAT HE NEEDED A TURN TO THE L BEFORE OR DURING THE TURN SO I COULD HAVE NOTIFIED DEP CTL SOONER. THE LACK OF COM BTWN THE FO AND MYSELF WAS THE BIGGEST FACTOR IN THIS SIT, IF HE HAD SAID HE NEEDED A TURN TO AVOID WX, I KNOW I WOULD HAVE STOPPED WHAT I WAS DOING (SINCE IT WAS NOT A SAFETY OF FLT ACTION) AND REQUESTED A TURN TO AVOID WX, WHICH WAS A SAFETY OF FLT ACTION.

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.