Narrative:

At mmx the crew was given a clearance to taxi to runway 5L. We were #1 for takeoff. Upon arriving at the end of runway 5L, I called the tower and advised ready for takeoff. The mmx tower controller issued a clearance for takeoff on runway 5L. The crew accomplished the before takeoff checklist and began the takeoff roll. At approximately 10 KTS below V1 the tower controller cautioned us about wake turbulence from a widebody transport that departed prior to us on the parallel runway 5R. At rotation the controller continued his comments and said '...I did not clear you for takeoff. Be careful in the future and contact departure.' the widebody transport aircraft that departed before us was approximately 6 mi ahead according to the TCASII. No evasive action was needed or taken. The crew of 3 all understood that we were cleared for takeoff. If there is ever any doubt from any of the crew I always confirm a clearance. En route, none of the crew could recall verbatim what the controller said prior to beginning the takeoff roll. Either the crew misunderstood the clearance or the controller issued a takeoff clearance by mistake. This was the last night of a 6 night trip sequence of all night back side of the clock cargo trips. Fatigue could have played a factor. The spanish controller seemed to be able to speak english well enough to understand. Without listening to the control tower tapes to confirm what was said, the whole event will remain a mystery.

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Original NASA ASRS Text

Title: A QUESTION OF A TKOF CLRNC ISSUED OR NOT AND WAKE TURB AT A FOREIGN ARPT.

Narrative: AT MMX THE CREW WAS GIVEN A CLRNC TO TAXI TO RWY 5L. WE WERE #1 FOR TKOF. UPON ARRIVING AT THE END OF RWY 5L, I CALLED THE TWR AND ADVISED READY FOR TKOF. THE MMX TWR CTLR ISSUED A CLRNC FOR TKOF ON RWY 5L. THE CREW ACCOMPLISHED THE BEFORE TKOF CHKLIST AND BEGAN THE TKOF ROLL. AT APPROX 10 KTS BELOW V1 THE TWR CTLR CAUTIONED US ABOUT WAKE TURB FROM A WDB THAT DEPARTED PRIOR TO US ON THE PARALLEL RWY 5R. AT ROTATION THE CTLR CONTINUED HIS COMMENTS AND SAID '...I DID NOT CLR YOU FOR TKOF. BE CAREFUL IN THE FUTURE AND CONTACT DEP.' THE WDB ACFT THAT DEPARTED BEFORE US WAS APPROX 6 MI AHEAD ACCORDING TO THE TCASII. NO EVASIVE ACTION WAS NEEDED OR TAKEN. THE CREW OF 3 ALL UNDERSTOOD THAT WE WERE CLRED FOR TKOF. IF THERE IS EVER ANY DOUBT FROM ANY OF THE CREW I ALWAYS CONFIRM A CLRNC. ENRTE, NONE OF THE CREW COULD RECALL VERBATIM WHAT THE CTLR SAID PRIOR TO BEGINNING THE TKOF ROLL. EITHER THE CREW MISUNDERSTOOD THE CLRNC OR THE CTLR ISSUED A TKOF CLRNC BY MISTAKE. THIS WAS THE LAST NIGHT OF A 6 NIGHT TRIP SEQUENCE OF ALL NIGHT BACK SIDE OF THE CLOCK CARGO TRIPS. FATIGUE COULD HAVE PLAYED A FACTOR. THE SPANISH CTLR SEEMED TO BE ABLE TO SPEAK ENGLISH WELL ENOUGH TO UNDERSTAND. WITHOUT LISTENING TO THE CTL TWR TAPES TO CONFIRM WHAT WAS SAID, THE WHOLE EVENT WILL REMAIN A MYSTERY.

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.