Narrative:

I was in the run-up area trying to unfoul a nasty left magneto. I had spent quite a bit of time in doing so. Finally, it cleared. However, I was still preoccupied with the problem. I taxied into position behind a cessna 'dab.' the tower told cessna 'dab' to taxi into position and hold. I then told the tower 'experimental 'abc' ready for takeoff.' I thought the tower called me back with instructions 'cleared to take off runway 30R.' I responded with 'experimental 'abc' cleared to take off runway 30R.' I crossed the hold bars onto the runway. I had confused 'abc' and 'dab.' the tower seemed confused as well. Lectured me for not holding, and then cleared me for takeoff. I, of course, said I was sorry. I had obviously confused my tail number. In looking back, 4 factors contributed to this problem: 1) I was confused with tail numbers. 2) I was preoccupied with the magneto problem, though I had fixed the problem. 3) tower should have stopped me when I read back clearance for one particular flight number, and addressed tower with experimental flight number. 4) I must also admit that when I'm not flying the experimental aircraft, I spend quite a bit of my CFI time in other aircraft. In the future, I will be more careful.

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Original NASA ASRS Text

Title: RV-6 TAXIED ONTO RWY 30R AT SJC WITHOUT ATC CLRNC.

Narrative: I WAS IN THE RUN-UP AREA TRYING TO UNFOUL A NASTY L MAGNETO. I HAD SPENT QUITE A BIT OF TIME IN DOING SO. FINALLY, IT CLRED. HOWEVER, I WAS STILL PREOCCUPIED WITH THE PROB. I TAXIED INTO POS BEHIND A CESSNA 'DAB.' THE TWR TOLD CESSNA 'DAB' TO TAXI INTO POS AND HOLD. I THEN TOLD THE TWR 'EXPERIMENTAL 'ABC' READY FOR TKOF.' I THOUGHT THE TWR CALLED ME BACK WITH INSTRUCTIONS 'CLRED TO TAKE OFF RWY 30R.' I RESPONDED WITH 'EXPERIMENTAL 'ABC' CLRED TO TAKE OFF RWY 30R.' I CROSSED THE HOLD BARS ONTO THE RWY. I HAD CONFUSED 'ABC' AND 'DAB.' THE TWR SEEMED CONFUSED AS WELL. LECTURED ME FOR NOT HOLDING, AND THEN CLRED ME FOR TKOF. I, OF COURSE, SAID I WAS SORRY. I HAD OBVIOUSLY CONFUSED MY TAIL NUMBER. IN LOOKING BACK, 4 FACTORS CONTRIBUTED TO THIS PROB: 1) I WAS CONFUSED WITH TAIL NUMBERS. 2) I WAS PREOCCUPIED WITH THE MAGNETO PROB, THOUGH I HAD FIXED THE PROB. 3) TWR SHOULD HAVE STOPPED ME WHEN I READ BACK CLRNC FOR ONE PARTICULAR FLT NUMBER, AND ADDRESSED TWR WITH EXPERIMENTAL FLT NUMBER. 4) I MUST ALSO ADMIT THAT WHEN I'M NOT FLYING THE EXPERIMENTAL ACFT, I SPEND QUITE A BIT OF MY CFI TIME IN OTHER ACFT. IN THE FUTURE, I WILL BE MORE CAREFUL.

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.