Pilot of small aircraft took off without takeoff clearance.

Attributes
ACN	183824
Time
Date	199107
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bna
State Reference	TN
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : instructional
Make Model Name	Small Aircraft, Low Wing, 1 Eng, Fixed Gear
Flight Phase	climbout : takeoff
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : instrument pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 320 flight time type : 75
ASRS Report	183824
Person 2
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
Events
Anomaly	non adherence : far non adherence : clearance other anomaly other
Independent Detector	other other : unspecified cockpit
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

We were in the parking area and ground control instructed us to taxi to the runway 2C. After performing the before takeoff check, we changed to the tower frequency and transmitted with the idea of takeoff. The tower controller instructed us to taxi into position and hold so we taxied onto the runway and the last clearance I was expecting was the initial heading to fly and the release for takeoff. After 20 seconds later the tower issued the following clearance: 'xx begin your 090 turn, contact departure'. He never specified this as 'after takeoff' instruction so we took off without causing any problem to other traffic. The controller should be so clear in his instructions that he would never put in doubt a single clearance and when he said 'xx begin...' I thought I was released for takeoff. Only 2 days later I read something about this in which he shall issue an additional clearance to prevent the possibility of the aircraft to begin the takeoff roll. (Order 7110.65F, ATC, change 5, pars 3-7.

Original NASA ASRS Text

Title: PLT OF SMA TOOK OFF WITHOUT TKOF CLRNC.

Narrative: WE WERE IN THE PARKING AREA AND GND CTL INSTRUCTED US TO TAXI TO THE RWY 2C. AFTER PERFORMING THE BEFORE TKOF CHK, WE CHANGED TO THE TWR FREQ AND XMITTED WITH THE IDEA OF TKOF. THE TWR CTLR INSTRUCTED US TO TAXI INTO POS AND HOLD SO WE TAXIED ONTO THE RWY AND THE LAST CLRNC I WAS EXPECTING WAS THE INITIAL HDG TO FLY AND THE RELEASE FOR TKOF. AFTER 20 SECONDS LATER THE TWR ISSUED THE FOLLOWING CLRNC: 'XX BEGIN YOUR 090 TURN, CONTACT DEP'. HE NEVER SPECIFIED THIS AS 'AFTER TKOF' INSTRUCTION SO WE TOOK OFF WITHOUT CAUSING ANY PROBLEM TO OTHER TFC. THE CTLR SHOULD BE SO CLR IN HIS INSTRUCTIONS THAT HE WOULD NEVER PUT IN DOUBT A SINGLE CLRNC AND WHEN HE SAID 'XX BEGIN...' I THOUGHT I WAS RELEASED FOR TKOF. ONLY 2 DAYS LATER I READ SOMETHING ABOUT THIS IN WHICH HE SHALL ISSUE AN ADDITIONAL CLRNC TO PREVENT THE POSSIBILITY OF THE ACFT TO BEGIN THE TKOF ROLL. (ORDER 7110.65F, ATC, CHANGE 5, PARS 3-7.

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.