Narrative:

Prescott tower cleared me to taxi to position and hold. I asked for a delay, to set the aircraft up for a short field takeoff. I taxied onto the runway and set the aircraft up for short fuel takeoff. Then I started my takeoff roll and takeoff. Tower advised me that I was not cleared for takeoff. I didn't realize that until I was told. I had to offset to the left for traffic ahead. Once I was clear of the class D airspace, I called tower and reported clear and I was sorry for the mix up. Tower said no problem þ frequency change approved. Far as I can tell there was no problem. I wanted to report this to be safe. To correct the problem I should have paid more attention to what the controller wa saying.

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Original NASA ASRS Text

Title: PLT REQUESTS TKOF DELAY TO PREPARE FOR A SHORT FIELD TKOF, THEN DEPARTS WITHOUT CLRNC. CTLR REMINDS HIM THAT HE WAS NOT CLRED. TKOF WITHOUT CLRNC.

Narrative: PRESCOTT TWR CLRED ME TO TAXI TO POS AND HOLD. I ASKED FOR A DELAY, TO SET THE ACFT UP FOR A SHORT FIELD TKOF. I TAXIED ONTO THE RWY AND SET THE ACFT UP FOR SHORT FUEL TKOF. THEN I STARTED MY TKOF ROLL AND TKOF. TWR ADVISED ME THAT I WAS NOT CLRED FOR TKOF. I DIDN'T REALIZE THAT UNTIL I WAS TOLD. I HAD TO OFFSET TO THE L FOR TFC AHEAD. ONCE I WAS CLR OF THE CLASS D AIRSPACE, I CALLED TWR AND RPTED CLR AND I WAS SORRY FOR THE MIX UP. TWR SAID NO PROB þ FREQ CHANGE APPROVED. FAR AS I CAN TELL THERE WAS NO PROB. I WANTED TO RPT THIS TO BE SAFE. TO CORRECT THE PROB I SHOULD HAVE PAID MORE ATTN TO WHAT THE CTLR WA SAYING.

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.