Narrative:

We may have taken off from runway 9 when we were told to position and hold! I don't know for sure exactly what was said! Our taxi clearance from bos ground told us we were going to depart on runway 9, but first we would have to hold short of runway 4L and contact bos tower on 128.8. Our initial contact with bos tower on 128.8 was to immediately cross runway 4L because there was traffic on a 1.5 mi final for that runway. I could see the lights of the aircraft that were on final for runway 4L and I knew as long as we expedited across runway 4L there would not be a conflict, which is what we did. Before we got to runway 9 we were completing the taxi checklist. Simultaneously, I answered the interphone call from a flight attendant saying that all the flight attendants were seated for takeoff and the captain answered the radio call from bos tower. The captain told me we were cleared for takeoff and he wanted the takeoff checklist. We completed the takeoff checklist and I did (what I thought was an uneventful takeoff) the takeoff from runway 9. At no time did I hear anything from the tower on the takeoff roll or climb out that would have made me believe that we were not cleared for takeoff. In retrospect, the captain told me he wasn't sure what he heard from the tower and that we should fill out an as soon as possible reporting form. Supplemental information from acn 595030: I noticed that the ATC departure controller seemed a little surprised to hear from us. He said something similar to '...ah...air carrier X...roger.' this gave me hesitation and caused me to reflect upon whether a takeoff clearance had been properly received and acknowledged.

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Original NASA ASRS Text

Title: A B737 FLT CREW IS UNSURE IF THEY WERE CLRED FOR TKOF AT BOS.

Narrative: WE MAY HAVE TAKEN OFF FROM RWY 9 WHEN WE WERE TOLD TO POS AND HOLD! I DON'T KNOW FOR SURE EXACTLY WHAT WAS SAID! OUR TAXI CLRNC FROM BOS GND TOLD US WE WERE GOING TO DEPART ON RWY 9, BUT FIRST WE WOULD HAVE TO HOLD SHORT OF RWY 4L AND CONTACT BOS TWR ON 128.8. OUR INITIAL CONTACT WITH BOS TWR ON 128.8 WAS TO IMMEDIATELY CROSS RWY 4L BECAUSE THERE WAS TFC ON A 1.5 MI FINAL FOR THAT RWY. I COULD SEE THE LIGHTS OF THE ACFT THAT WERE ON FINAL FOR RWY 4L AND I KNEW AS LONG AS WE EXPEDITED ACROSS RWY 4L THERE WOULD NOT BE A CONFLICT, WHICH IS WHAT WE DID. BEFORE WE GOT TO RWY 9 WE WERE COMPLETING THE TAXI CHKLIST. SIMULTANEOUSLY, I ANSWERED THE INTERPHONE CALL FROM A FLT ATTENDANT SAYING THAT ALL THE FLT ATTENDANTS WERE SEATED FOR TKOF AND THE CAPT ANSWERED THE RADIO CALL FROM BOS TWR. THE CAPT TOLD ME WE WERE CLRED FOR TKOF AND HE WANTED THE TKOF CHKLIST. WE COMPLETED THE TKOF CHKLIST AND I DID (WHAT I THOUGHT WAS AN UNEVENTFUL TKOF) THE TKOF FROM RWY 9. AT NO TIME DID I HEAR ANYTHING FROM THE TWR ON THE TKOF ROLL OR CLBOUT THAT WOULD HAVE MADE ME BELIEVE THAT WE WERE NOT CLRED FOR TKOF. IN RETROSPECT, THE CAPT TOLD ME HE WASN'T SURE WHAT HE HEARD FROM THE TWR AND THAT WE SHOULD FILL OUT AN ASAP RPTING FORM. SUPPLEMENTAL INFO FROM ACN 595030: I NOTICED THAT THE ATC DEP CTLR SEEMED A LITTLE SURPRISED TO HEAR FROM US. HE SAID SOMETHING SIMILAR TO '...AH...ACR X...ROGER.' THIS GAVE ME HESITATION AND CAUSED ME TO REFLECT UPON WHETHER A TKOF CLRNC HAD BEEN PROPERLY RECEIVED AND ACKNOWLEDGED.

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.