Narrative:

Leaving dal, our departure instructions were the DALL5 departure, which is runway heading until 5.5 DME, right turn to 360 degrees for vectors, climb and maintain 5000 ft. It was my leg (captain) but after engine start, we had trouble getting pushback clearance. After troubleshooting, we discovered the first officer hand microphone was stuck. We were late, so instead of having the flight engineer change out the microphone, I decided to go ahead and push and start taxiing -- since we were late. Since my radios worked, I told the first officer to brief and do the takeoff. During taxi out, the flight engineer had time and changed out the first officer's microphone. It checked good, so I changed back to my departure and I briefed the pertinent items, including the departure procedure. But, when it came time for takeoff, I initiated a right turn to 360 degrees at 500 ft AGL. Tower was watching and asked if we were flying runway heading. Upon hearing their transmission, I immediately corrected back to runway heading. Tower's vigilance kept us from exceeding more than a 15 degree heading deviation. Contributing factors were: 1) being late, not changing the microphone out in the blocks prior to taxi, and 2) the confusion of the change from 'my takeoff' to 'your takeoff' back to 'my takeoff.'

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Original NASA ASRS Text

Title: ACR DC8 PIC MISINTERPS IFR DEP PROC AND BEGINS A TURN 1 MI OFF DEP END OF RWY INSTEAD OF AT 5 PT 5 MI.

Narrative: LEAVING DAL, OUR DEP INSTRUCTIONS WERE THE DALL5 DEP, WHICH IS RWY HDG UNTIL 5.5 DME, R TURN TO 360 DEGS FOR VECTORS, CLB AND MAINTAIN 5000 FT. IT WAS MY LEG (CAPT) BUT AFTER ENG START, WE HAD TROUBLE GETTING PUSHBACK CLRNC. AFTER TROUBLESHOOTING, WE DISCOVERED THE FO HAND MIKE WAS STUCK. WE WERE LATE, SO INSTEAD OF HAVING THE FE CHANGE OUT THE MIKE, I DECIDED TO GO AHEAD AND PUSH AND START TAXIING -- SINCE WE WERE LATE. SINCE MY RADIOS WORKED, I TOLD THE FO TO BRIEF AND DO THE TKOF. DURING TAXI OUT, THE FE HAD TIME AND CHANGED OUT THE FO'S MIKE. IT CHKED GOOD, SO I CHANGED BACK TO MY DEP AND I BRIEFED THE PERTINENT ITEMS, INCLUDING THE DEP PROC. BUT, WHEN IT CAME TIME FOR TKOF, I INITIATED A R TURN TO 360 DEGS AT 500 FT AGL. TWR WAS WATCHING AND ASKED IF WE WERE FLYING RWY HDG. UPON HEARING THEIR XMISSION, I IMMEDIATELY CORRECTED BACK TO RWY HDG. TWR'S VIGILANCE KEPT US FROM EXCEEDING MORE THAN A 15 DEG HDG DEV. CONTRIBUTING FACTORS WERE: 1) BEING LATE, NOT CHANGING THE MIKE OUT IN THE BLOCKS PRIOR TO TAXI, AND 2) THE CONFUSION OF THE CHANGE FROM 'MY TKOF' TO 'YOUR TKOF' BACK TO 'MY TKOF.'

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.