Narrative:

On taxi out, we learned that the runways being used for takeoff were not included in our takeoff data. We requested new data. After receiving new data, as well as the final load data, we compared our weight to the takeoff data and concluded that the runway that we were assigned was good for takeoff. The limiting factors were: 1) runway weight, 2) climb limit weight, 3) structural limit weight and landing weight limit. In this case, the landing weight limit was about equal to the runway limit weight and was the most restrictive of all, it seemed. We were expedited to the runway and cleared for takeoff. The takeoff roll was long, but not unusually so, considering our weight. We became airborne fairly near the end of the runway, close enough to get my attention, but not really unusual. The flight was a 4 hour flight, and, as is my habit, I later reviewed the takeoff data. At first, everything looked fine. Then, I realized that I had not completely checked the winds on the new runway that we had been assigned for takeoff. I remember looking for a windsock as we taxied to the runway. I did not see one, and about then, the new takeoff data that we had requested came off the printer, and I became involved in checking the runway limit and the landing limit, which I knew we were close to. Shortly thereafter, we were cleared onto the runway. I also remember the controller hurriedly clearing us for a takeoff and I'm sure he did not mention the wind. In further review of our takeoff data, I realized that, for every KT of tailwind, we would be penalized 1000 pounds on the runway limit weight. Since we were just under the runway limit weight, even 1 KT of tailwind would put us over the limit. I then looked at the ATIS, which was 1 hour old at the time of our takeoff, and it showed a wind that would have given us a 5 KT tailwind. I later checked the hourly WX reports and the wind was steady out of the same direction all day. I am assuming that I took off with about 3-5 KTS of tailwind, which would have put me over the runway limit by 3000-5000 pounds. Cause of problem: not considering the wind factor upon the runway limit weight. Contributing factors: change of plan (new runway) during a busy period (taxi). No windsock installation (there should be windsocks at every runway threshold). No wind call by controller (wind calls should include not only the wind direction and velocity, but the crosswind or tailwind component). Possible solutions -- see 2) and 3) above. Also, a standardized performance checklist for variations in the takeoff data.

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Original NASA ASRS Text

Title: TKOF PROC DOWNWIND TKOF. UNAUTH TKOF.

Narrative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

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.