Narrative:

We were turning on taxiway C for departure on runway 10L sfo. This required a back-track on 10L to use full length for takeoff. We were cleared to enter the active runway 01R romeo taxiway. We were told by the tower controller to hold, and then, 'cleared to roll it,' to which the first officer responded, 'cleared to roll it.' I became busy with my duties on final checklist and did not clearly her anymore tower transmission directed at us. Upon completion of the turn, the captain gave control of the aircraft to the first officer, who began advancing the throttles for takeoff. I then asked, 'are we cleared for takeoff?', to which both the captain and first officer said, 'yeah, we're cleared.' the captain transmitted to the tower, 'aircraft is rolling,' to which there was no response from the tower. After completion of the flight we found out that we took off west/O takeoff clearance. I believe the controller's use of non standard vernacular in the order given caused the pilots to believe they were cleared for takeoff. I believe the no response by the controller when told that the aircraft was rolling contributed to an unsafe situation. The pilot's acceptance of a non standard clearance; i.e., taking off west/O the words, 'cleared for takeoff.' also contributing to this is the fact that international pilots are used to hearing and being given non standard clrncs with non standard vernacular in foreign countries.

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Original NASA ASRS Text

Title: FLT CREW OF WDB BACK-TAXIING ON RWY TO TURN AROUND AND TKOF WERE ADVISED BY TWR TO KEEP IT ROLLING. FLT REPEATED PHRASE AND TOOK OFF. ALLEGED BY TWR ACFT DID NOT HAVE TKOF CLRNC.

Narrative: WE WERE TURNING ON TXWY C FOR DEP ON RWY 10L SFO. THIS REQUIRED A BACK-TRACK ON 10L TO USE FULL LENGTH FOR TKOF. WE WERE CLRED TO ENTER THE ACTIVE RWY 01R ROMEO TXWY. WE WERE TOLD BY THE TWR CTLR TO HOLD, AND THEN, 'CLRED TO ROLL IT,' TO WHICH THE F/O RESPONDED, 'CLRED TO ROLL IT.' I BECAME BUSY WITH MY DUTIES ON FINAL CHKLIST AND DID NOT CLEARLY HER ANYMORE TWR XMISSION DIRECTED AT US. UPON COMPLETION OF THE TURN, THE CAPT GAVE CTL OF THE ACFT TO THE F/O, WHO BEGAN ADVANCING THE THROTTLES FOR TKOF. I THEN ASKED, 'ARE WE CLRED FOR TKOF?', TO WHICH BOTH THE CAPT AND F/O SAID, 'YEAH, WE'RE CLRED.' THE CAPT XMITTED TO THE TWR, 'ACFT IS ROLLING,' TO WHICH THERE WAS NO RESPONSE FROM THE TWR. AFTER COMPLETION OF THE FLT WE FOUND OUT THAT WE TOOK OFF W/O TKOF CLRNC. I BELIEVE THE CTLR'S USE OF NON STANDARD VERNACULAR IN THE ORDER GIVEN CAUSED THE PLTS TO BELIEVE THEY WERE CLRED FOR TKOF. I BELIEVE THE NO RESPONSE BY THE CTLR WHEN TOLD THAT THE ACFT WAS ROLLING CONTRIBUTED TO AN UNSAFE SITUATION. THE PLT'S ACCEPTANCE OF A NON STANDARD CLRNC; I.E., TAKING OFF W/O THE WORDS, 'CLRED FOR TKOF.' ALSO CONTRIBUTING TO THIS IS THE FACT THAT INTL PLTS ARE USED TO HEARING AND BEING GIVEN NON STANDARD CLRNCS WITH NON STANDARD VERNACULAR IN FOREIGN COUNTRIES.

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.