Narrative:

ATIS at lax reported 12 degrees C, wind 100/08 for runway 25R. We were just legal for takeoff at 350000#, flap 8/16 and bleeds closed on the widebody transport with our charts, along with takeoff clearance tower. Reported wind at 100 degrees, 12 KTS our precomputed data for takeoff was no good and this exceeded our 10 KT tailwind limit for the widebody transport. We requested runway 7 and were told to expect 20-30 min delay. At the end of runway 7 we waited 25 min while there we observed winds on windsock of 090-100 degrees/15 KTS. Tower never reported wind over 11 KTS except for our takeoff clearance on runway 25. Other flts landing and departing questioned the runway selection but did not request runway 7 as we did. The impasse was resolved with wind shift to 200-220 at 7 KTS. We taxied back to runway 25R and departed west/O incident. We would have sat for runway 7 until flameout due to lax ATC using a downwind departure procedure exceeding aircraft limits. We feel the tower lied about the wind based on our observations and they would not alter their procedures when challenged. It is a shame other pilots would not challenge lax tower and force a runway change.

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Original NASA ASRS Text

Title: ATCT CONTINUED USING DOWNWIND RWY FOR OPERATION EVEN THOUGH TAILWIND EXCEEDED MAXIMUM TAIL WIND COMPONENT FOR ACR ACFT.

Narrative: ATIS AT LAX RPTED 12 DEGS C, WIND 100/08 FOR RWY 25R. WE WERE JUST LEGAL FOR TKOF AT 350000#, FLAP 8/16 AND BLEEDS CLOSED ON THE WDB WITH OUR CHARTS, ALONG WITH TKOF CLRNC TWR. RPTED WIND AT 100 DEGS, 12 KTS OUR PRECOMPUTED DATA FOR TKOF WAS NO GOOD AND THIS EXCEEDED OUR 10 KT TAILWIND LIMIT FOR THE WDB. WE REQUESTED RWY 7 AND WERE TOLD TO EXPECT 20-30 MIN DELAY. AT THE END OF RWY 7 WE WAITED 25 MIN WHILE THERE WE OBSERVED WINDS ON WINDSOCK OF 090-100 DEGS/15 KTS. TWR NEVER RPTED WIND OVER 11 KTS EXCEPT FOR OUR TKOF CLRNC ON RWY 25. OTHER FLTS LNDG AND DEPARTING QUESTIONED THE RWY SELECTION BUT DID NOT REQUEST RWY 7 AS WE DID. THE IMPASSE WAS RESOLVED WITH WIND SHIFT TO 200-220 AT 7 KTS. WE TAXIED BACK TO RWY 25R AND DEPARTED W/O INCIDENT. WE WOULD HAVE SAT FOR RWY 7 UNTIL FLAMEOUT DUE TO LAX ATC USING A DOWNWIND DEP PROC EXCEEDING ACFT LIMITS. WE FEEL THE TWR LIED ABOUT THE WIND BASED ON OUR OBSERVATIONS AND THEY WOULD NOT ALTER THEIR PROCS WHEN CHALLENGED. IT IS A SHAME OTHER PLTS WOULD NOT CHALLENGE LAX TWR AND FORCE A RWY CHANGE.

Data retrieved from NASA's ASRS site as of August 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.