Narrative:

Taxiing out for takeoff from jfk the first officer and myself discussed the fact that the WX was deteriorating and the wind was shifting. ATC was busy; but not out of the ordinary. As we lined up for takeoff; and completed the before takeoff checklist; ATC gave us a WX report; and asked us if we were ok to take off. I wrote down the wind that I thought that I had heard ATC report; responded that we were good for takeoff; and departed jfk. On arrival at phx; I was advised that I had departed with a 21 KT tailwind; which is outside the limits of the airplane. This confounded me; as I had written down the wind report that I had heard; which was 210 degrees at 10 KTS. I think that ATC reported a wind of 010 degrees at 21 KTS; but I wrote down 210 degrees at 10 KTS. As we were departing runway 22L at jfk; 210 degrees at 10 KTS would not be out of the limits of the airplane. Obviously; 010 degrees 21 KTS would be outside the limits. This situation would not have happened had I paid closer attention to the wind report that ATC gave to me. Any time you (I) are/am asked by ATC if you (I) are/am good for takeoff; this should make me wonder; 'why am I being asked that?' unfortunately; I had written down the wrong information; I thought that I was legal for takeoff. I simply transposed 2 numbers; which was a critical error. Maybe I did this because I was given the information as we were completing the checklist. I don't know. In the future; when I am asked if I am 'good to go;' I will pause; possibly ask for more information; then assess the situation. Transposing 2 numbers is a small mistake that could have huge ramifications.

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Original NASA ASRS Text

Title: AN A320 FLT CREW TOOK OFF WITH EXCESSIVE TAILWIND COMPONENT BECAUSE THEY COPIED THE WIND DATA FROM THE TWR INCORRECTLY.

Narrative: TAXIING OUT FOR TKOF FROM JFK THE FO AND MYSELF DISCUSSED THE FACT THAT THE WX WAS DETERIORATING AND THE WIND WAS SHIFTING. ATC WAS BUSY; BUT NOT OUT OF THE ORDINARY. AS WE LINED UP FOR TKOF; AND COMPLETED THE BEFORE TKOF CHKLIST; ATC GAVE US A WX RPT; AND ASKED US IF WE WERE OK TO TAKE OFF. I WROTE DOWN THE WIND THAT I THOUGHT THAT I HAD HEARD ATC RPT; RESPONDED THAT WE WERE GOOD FOR TKOF; AND DEPARTED JFK. ON ARR AT PHX; I WAS ADVISED THAT I HAD DEPARTED WITH A 21 KT TAILWIND; WHICH IS OUTSIDE THE LIMITS OF THE AIRPLANE. THIS CONFOUNDED ME; AS I HAD WRITTEN DOWN THE WIND RPT THAT I HAD HEARD; WHICH WAS 210 DEGS AT 10 KTS. I THINK THAT ATC RPTED A WIND OF 010 DEGS AT 21 KTS; BUT I WROTE DOWN 210 DEGS AT 10 KTS. AS WE WERE DEPARTING RWY 22L AT JFK; 210 DEGS AT 10 KTS WOULD NOT BE OUT OF THE LIMITS OF THE AIRPLANE. OBVIOUSLY; 010 DEGS 21 KTS WOULD BE OUTSIDE THE LIMITS. THIS SITUATION WOULD NOT HAVE HAPPENED HAD I PAID CLOSER ATTN TO THE WIND RPT THAT ATC GAVE TO ME. ANY TIME YOU (I) ARE/AM ASKED BY ATC IF YOU (I) ARE/AM GOOD FOR TKOF; THIS SHOULD MAKE ME WONDER; 'WHY AM I BEING ASKED THAT?' UNFORTUNATELY; I HAD WRITTEN DOWN THE WRONG INFO; I THOUGHT THAT I WAS LEGAL FOR TKOF. I SIMPLY TRANSPOSED 2 NUMBERS; WHICH WAS A CRITICAL ERROR. MAYBE I DID THIS BECAUSE I WAS GIVEN THE INFO AS WE WERE COMPLETING THE CHKLIST. I DON'T KNOW. IN THE FUTURE; WHEN I AM ASKED IF I AM 'GOOD TO GO;' I WILL PAUSE; POSSIBLY ASK FOR MORE INFO; THEN ASSESS THE SITUATION. TRANSPOSING 2 NUMBERS IS A SMALL MISTAKE THAT COULD HAVE HUGE RAMIFICATIONS.

Data retrieved from NASA's ASRS site as of January 2009 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.