An air carrier SF340 crew took off without clearance.

Attributes
ACN	357260
Time
Date	199612
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : yyz
State Reference	ON
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : yyz
Operator	common carrier : air carrier
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Navigation In Use	Other Other
Flight Phase	climbout : takeoff
Route In Use	departure other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 120 flight time total : 7000 flight time type : 200
ASRS Report	357260
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	incursion : runway non adherence : clearance non adherence : far non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Takeoff without clearance. Toronto tower clearance was position and wait, runway 24R. First officer replied correct response. Crew finished line- up checklist while taxiing onto runway. Captain commenced takeoff with first officer's support. ATC advised us of our error once we were airborne. Contributing factors were crew fatigue and language barrier. Although both ATC and flight crew spoke english, my understanding of their radio xmissions was and is difficult. Fatigue was also a factor. The flight crew's duty day started at XA30 am. This was our second day in a row with early morning reports and long duty days.

Original NASA ASRS Text

Title: AN ACR SF340 CREW TOOK OFF WITHOUT CLRNC.

Narrative: TKOF WITHOUT CLRNC. TORONTO TWR CLRNC WAS POS AND WAIT, RWY 24R. FO REPLIED CORRECT RESPONSE. CREW FINISHED LINE- UP CHKLIST WHILE TAXIING ONTO RWY. CAPT COMMENCED TKOF WITH FO'S SUPPORT. ATC ADVISED US OF OUR ERROR ONCE WE WERE AIRBORNE. CONTRIBUTING FACTORS WERE CREW FATIGUE AND LANGUAGE BARRIER. ALTHOUGH BOTH ATC AND FLC SPOKE ENGLISH, MY UNDERSTANDING OF THEIR RADIO XMISSIONS WAS AND IS DIFFICULT. FATIGUE WAS ALSO A FACTOR. THE FLC'S DUTY DAY STARTED AT XA30 AM. THIS WAS OUR SECOND DAY IN A ROW WITH EARLY MORNING RPTS AND LONG DUTY DAYS.

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.