Narrative:

We were cleared for the seaview 1 departure that has an immediate turn to the left, followed by several crossing restrs in the climb. It was busy, and as we took the runway the tower cleared us for takeoff and told us to fly runway heading. I read back the clearance and we took off. At 400 ft, the first officer started a very slow turn to the left. We had just followed a heavy aircraft on takeoff and I thought the turn was a result of wake turbulence and not a purposeful turn. Tower advised us to stop the turn. We stopped immediately, and I read back 'fly runway heading.' we were not more than 10 degrees off the assigned heading of 310 degrees. The first officer said he did not hear his clearance. I believe concentrating on the departure, staying out of the wake of the traffic we followed, were contributing factors.

Related reports:

Google
 

Original NASA ASRS Text

Title: A TURBOJET CAPT, DEPARTING JFK, RPTED THAT THE PF TURNED L RATHER THAN REMAINING ON RWY HDG AS REQUESTED BY THE TWR.

Narrative: WE WERE CLRED FOR THE SEAVIEW 1 DEP THAT HAS AN IMMEDIATE TURN TO THE L, FOLLOWED BY SEVERAL XING RESTRS IN THE CLB. IT WAS BUSY, AND AS WE TOOK THE RWY THE TWR CLRED US FOR TKOF AND TOLD US TO FLY RWY HDG. I READ BACK THE CLRNC AND WE TOOK OFF. AT 400 FT, THE FO STARTED A VERY SLOW TURN TO THE L. WE HAD JUST FOLLOWED A HVY ACFT ON TKOF AND I THOUGHT THE TURN WAS A RESULT OF WAKE TURB AND NOT A PURPOSEFUL TURN. TWR ADVISED US TO STOP THE TURN. WE STOPPED IMMEDIATELY, AND I READ BACK 'FLY RWY HDG.' WE WERE NOT MORE THAN 10 DEGS OFF THE ASSIGNED HDG OF 310 DEGS. THE FO SAID HE DID NOT HEAR HIS CLRNC. I BELIEVE CONCENTRATING ON THE DEP, STAYING OUT OF THE WAKE OF THE TFC WE FOLLOWED, WERE CONTRIBUTING FACTORS.

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.