Narrative:

On 12/fri/89, at vny with traffic departing to the north, I had completed run-up procedures at intersection 11 golf, just in front of the control tower. The WX was clear with excellent visibility. I called clearance delivery and requested clearance through the bur arsa on departure. I then completed the run-up, and called the tower, saying 'vny tower, small transport a xx at 11G ready for takeoff--requesting straight out departure.' the tower replied, 'xx, what is your location?' I repeated, 'I am at 11G.' I then heard 'cleared for takeoff, straight out departure approved.' I then executed a rolling takeoff, accelerating rapidly. At about liftoff speed I heard the controller say, 'abort your takeoff,' but due to the high engine noise, I did not hear the aircraft identify. I made a quick decision to continue the takeoff for the following reasons: there was no conflicting ground traffic ahead of me, I was not certain the abort was intended for me, and I was rapidly running out of a safe stopping distance. On climb out the tower requested some other aircraft to turn left 20 degrees. There was a single engine small aircraft taking off ahead of me using 34R, a parallel runway. He did not make a right turn, so I concluded there was someone behind me who had been given the left turn. The tower then informed me I had not been cleared for takeoff. I was stunned by the remark and told the tower what I heard, 'cleared for takeoff with a straight out departure approved.' the tower replied, 'that clearance was for an small transport B.' no other comments were received from the tower. I then switched over to bur departure control and continued the departure to the north. I can only surmise another aircraft (the small transport B) made a simultaneous takeoff starting at some point behind me. How could something like this happen to a pilot with 45 yrs flying experience with thousands of takeoffs and lndgs? Did I hear what I wanted to hear and not what was actually said? After answering his question as to my location, I didn't hear anything like 'hold,' or 'break,' followed by clearance for another aircraft--I heard 'cleared for takeoff.' were our 2 north#'south similar enough to have caused the confusion? I assume I will be given an opportunity to listen to the tape and find the answer. Clear communication is key to safe operations, ground or air. I was using cockpit speakers rather than headphones this particular day--never again! My run-up and rolling takeoff was from an opp direction high-speed turn-off (to which I had been cleared). There was not a good view of the remaining downwind runway. I will definitely not do that again.

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Original NASA ASRS Text

Title: SMT DEPARTS FROM INTERSECTION APPARENTLY WITHOUT TKOF CLRNC CAUSING ANOTHER SMT TO ABORT TKOF.

Narrative: ON 12/FRI/89, AT VNY WITH TFC DEPARTING TO THE N, I HAD COMPLETED RUN-UP PROCS AT INTXN 11 GOLF, JUST IN FRONT OF THE CTL TWR. THE WX WAS CLR WITH EXCELLENT VISIBILITY. I CALLED CLRNC DELIVERY AND REQUESTED CLRNC THROUGH THE BUR ARSA ON DEP. I THEN COMPLETED THE RUN-UP, AND CALLED THE TWR, SAYING 'VNY TWR, SMT A XX AT 11G READY FOR TKOF--REQUESTING STRAIGHT OUT DEP.' THE TWR REPLIED, 'XX, WHAT IS YOUR LOCATION?' I REPEATED, 'I AM AT 11G.' I THEN HEARD 'CLRED FOR TKOF, STRAIGHT OUT DEP APPROVED.' I THEN EXECUTED A ROLLING TKOF, ACCELERATING RAPIDLY. AT ABOUT LIFTOFF SPD I HEARD THE CTLR SAY, 'ABORT YOUR TKOF,' BUT DUE TO THE HIGH ENG NOISE, I DID NOT HEAR THE ACFT IDENT. I MADE A QUICK DECISION TO CONTINUE THE TKOF FOR THE FOLLOWING REASONS: THERE WAS NO CONFLICTING GND TFC AHEAD OF ME, I WAS NOT CERTAIN THE ABORT WAS INTENDED FOR ME, AND I WAS RAPIDLY RUNNING OUT OF A SAFE STOPPING DISTANCE. ON CLBOUT THE TWR REQUESTED SOME OTHER ACFT TO TURN LEFT 20 DEGS. THERE WAS A SINGLE ENG SMA TAKING OFF AHEAD OF ME USING 34R, A PARALLEL RWY. HE DID NOT MAKE A RIGHT TURN, SO I CONCLUDED THERE WAS SOMEONE BEHIND ME WHO HAD BEEN GIVEN THE LEFT TURN. THE TWR THEN INFORMED ME I HAD NOT BEEN CLRED FOR TKOF. I WAS STUNNED BY THE REMARK AND TOLD THE TWR WHAT I HEARD, 'CLRED FOR TKOF WITH A STRAIGHT OUT DEP APPROVED.' THE TWR REPLIED, 'THAT CLRNC WAS FOR AN SMT B.' NO OTHER COMMENTS WERE RECEIVED FROM THE TWR. I THEN SWITCHED OVER TO BUR DEP CTL AND CONTINUED THE DEP TO THE N. I CAN ONLY SURMISE ANOTHER ACFT (THE SMT B) MADE A SIMULTANEOUS TKOF STARTING AT SOME POINT BEHIND ME. HOW COULD SOMETHING LIKE THIS HAPPEN TO A PLT WITH 45 YRS FLYING EXPERIENCE WITH THOUSANDS OF TKOFS AND LNDGS? DID I HEAR WHAT I WANTED TO HEAR AND NOT WHAT WAS ACTUALLY SAID? AFTER ANSWERING HIS QUESTION AS TO MY LOCATION, I DIDN'T HEAR ANYTHING LIKE 'HOLD,' OR 'BREAK,' FOLLOWED BY CLRNC FOR ANOTHER ACFT--I HEARD 'CLRED FOR TKOF.' WERE OUR 2 N#'S SIMILAR ENOUGH TO HAVE CAUSED THE CONFUSION? I ASSUME I WILL BE GIVEN AN OPPORTUNITY TO LISTEN TO THE TAPE AND FIND THE ANSWER. CLEAR COM IS KEY TO SAFE OPS, GND OR AIR. I WAS USING COCKPIT SPEAKERS RATHER THAN HEADPHONES THIS PARTICULAR DAY--NEVER AGAIN! MY RUN-UP AND ROLLING TKOF WAS FROM AN OPP DIRECTION HIGH-SPD TURN-OFF (TO WHICH I HAD BEEN CLRED). THERE WAS NOT A GOOD VIEW OF THE REMAINING DOWNWIND RWY. I WILL DEFINITELY NOT DO THAT AGAIN.

Data retrieved from NASA's ASRS site as of August 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.