Cessna 337 pilot unknowingly took off without clearance.

Attributes
ACN	548517
Time
Date	200205
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : luk.airport
State Reference	OH
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Super Skymaster
Operating Under FAR Part	Part 91
Flight Phase	climbout : takeoff
Flight Plan	None
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : multi engine pilot : private
Experience	flight time last 90 days : 20 flight time total : 1950
ASRS Report	548517
Person 2
Affiliation	government : faa
Function	controller : local
Events
Anomaly	incursion : runway non adherence : far non adherence : clearance
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was instructed to taxi to runway 21L. I read back taxi instructions to the runup area for 21L. After runup and preflight checks, I advised tower I was ready for departure on 21L. Tower instructed me to hold short of runway 25 and I read back and complied. The tower was very busy with xmissions since a vehicle had appeared on runway 21L and it was necessary to change traffic to another runway. The tower told me take runway 25, which I did and thought the tower had cleared me for takeoff in that transmission. Shortly after takeoff, the tower contacted me and stated I had taken off without clearance and to call the tower after landing at my destination. I complied. I was told this incident was a possible runway incursion.

Original NASA ASRS Text

Title: CESSNA 337 PLT UNKNOWINGLY TOOK OFF WITHOUT CLRNC.

Narrative: I WAS INSTRUCTED TO TAXI TO RWY 21L. I READ BACK TAXI INSTRUCTIONS TO THE RUNUP AREA FOR 21L. AFTER RUNUP AND PREFLT CHECKS, I ADVISED TWR I WAS READY FOR DEP ON 21L. TWR INSTRUCTED ME TO HOLD SHORT OF RWY 25 AND I READ BACK AND COMPLIED. THE TWR WAS VERY BUSY WITH XMISSIONS SINCE A VEHICLE HAD APPEARED ON RWY 21L AND IT WAS NECESSARY TO CHANGE TFC TO ANOTHER RWY. THE TWR TOLD ME TAKE RWY 25, WHICH I DID AND THOUGHT THE TWR HAD CLRED ME FOR TKOF IN THAT XMISSION. SHORTLY AFTER TKOF, THE TWR CONTACTED ME AND STATED I HAD TAKEN OFF WITHOUT CLRNC AND TO CALL THE TWR AFTER LNDG AT MY DEST. I COMPLIED. I WAS TOLD THIS INCIDENT WAS A POSSIBLE RWY INCURSION.

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.