Narrative:

Sfo in standard runway confign: 1L/right for takeoff; runway 28L/right for arrs. ATIS winds 220 degrees/8 KTS. During taxi to runway 1R we noticed the windsock near the threshold standing straight out at a tailwind angle; so we inquired. We were told 'departure winds 220 at 12.' since this exceeded our maximum allowable tailwind component of 4 KTS we asked for and were assigned taxi to runway 28L. During the taxi we noticed the wind direction and velocity was generating more controversy at runway 1L and right; and other aircraft were also requesting runway 28L for takeoff. On tower frequency; we noticed that the controller was issuing 'runway 1L departure wind 260 at 21' as part of the takeoff clearance; and most flts were departing with that information. However; it was obvious by watching a couple of heavy aircraft stagger off the far end that there was considerably more tailwind component than the 20 degrees or so being reported by the tower. We waited on tower frequency for a considerable length of time at runway 28L. At one point a pilot at runway 1L/right began to question the controller in detail about the wind; and she finally said something like this 'departure wind 260 at 21; centerfield wind 210 at 18.' it was apparent that the wind was 'wrapping' as it does at sfo occasionally when it is out of the southwest; and the centerfield wind; 210 degrees at 18 KTS; almost a direct tailwind component of 18 KTS -- was the wind condition affecting the departing aircraft during most of the takeoff roll and lift-off. The pilots that were so advised were; of course; refusing runway 1L and right. But that information was not always made available along with the takeoff clearance. In spite of this; the tower continued to issue runway 1L and right takeoff clrncs using only the 'departure end' wind of 260 degrees at 15-20 KTS or so. Pilots unaware of the excessive centerfield tailwind; continued to make takeoffs on those runways; and only the pilots that questioned the controller intensively were given that vital information. Many yrs ago an airliner B747 struck light stanchions off the departure end of runway 1R in a late-rotation accident; in similar circumstances. Sfo often stretches WX and wind limits to the maximum in order to keep traffic flowing. I do not know what formal ATC policy is regarding issuance of wind information in conjunction with takeoff clrncs. However; concealing this kind of information from pilots could lead to a disaster.

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Original NASA ASRS Text

Title: SFO ACR DEP EXPRESSED CONCERN REGARDING WIND INFO PROVIDED BY ATC WITH TKOF CLRNC; INDICATING MORE RELEVANT INFO WAS AVAILABLE.

Narrative: SFO IN STANDARD RWY CONFIGN: 1L/R FOR TKOF; RWY 28L/R FOR ARRS. ATIS WINDS 220 DEGS/8 KTS. DURING TAXI TO RWY 1R WE NOTICED THE WINDSOCK NEAR THE THRESHOLD STANDING STRAIGHT OUT AT A TAILWIND ANGLE; SO WE INQUIRED. WE WERE TOLD 'DEP WINDS 220 AT 12.' SINCE THIS EXCEEDED OUR MAX ALLOWABLE TAILWIND COMPONENT OF 4 KTS WE ASKED FOR AND WERE ASSIGNED TAXI TO RWY 28L. DURING THE TAXI WE NOTICED THE WIND DIRECTION AND VELOCITY WAS GENERATING MORE CONTROVERSY AT RWY 1L AND R; AND OTHER ACFT WERE ALSO REQUESTING RWY 28L FOR TKOF. ON TWR FREQ; WE NOTICED THAT THE CTLR WAS ISSUING 'RWY 1L DEP WIND 260 AT 21' AS PART OF THE TKOF CLRNC; AND MOST FLTS WERE DEPARTING WITH THAT INFO. HOWEVER; IT WAS OBVIOUS BY WATCHING A COUPLE OF HVY ACFT STAGGER OFF THE FAR END THAT THERE WAS CONSIDERABLY MORE TAILWIND COMPONENT THAN THE 20 DEGS OR SO BEING RPTED BY THE TWR. WE WAITED ON TWR FREQ FOR A CONSIDERABLE LENGTH OF TIME AT RWY 28L. AT ONE POINT A PLT AT RWY 1L/R BEGAN TO QUESTION THE CTLR IN DETAIL ABOUT THE WIND; AND SHE FINALLY SAID SOMETHING LIKE THIS 'DEP WIND 260 AT 21; CENTERFIELD WIND 210 AT 18.' IT WAS APPARENT THAT THE WIND WAS 'WRAPPING' AS IT DOES AT SFO OCCASIONALLY WHEN IT IS OUT OF THE SW; AND THE CENTERFIELD WIND; 210 DEGS AT 18 KTS; ALMOST A DIRECT TAILWIND COMPONENT OF 18 KTS -- WAS THE WIND CONDITION AFFECTING THE DEPARTING ACFT DURING MOST OF THE TKOF ROLL AND LIFT-OFF. THE PLTS THAT WERE SO ADVISED WERE; OF COURSE; REFUSING RWY 1L AND R. BUT THAT INFO WAS NOT ALWAYS MADE AVAILABLE ALONG WITH THE TKOF CLRNC. IN SPITE OF THIS; THE TWR CONTINUED TO ISSUE RWY 1L AND R TKOF CLRNCS USING ONLY THE 'DEP END' WIND OF 260 DEGS AT 15-20 KTS OR SO. PLTS UNAWARE OF THE EXCESSIVE CENTERFIELD TAILWIND; CONTINUED TO MAKE TKOFS ON THOSE RWYS; AND ONLY THE PLTS THAT QUESTIONED THE CTLR INTENSIVELY WERE GIVEN THAT VITAL INFO. MANY YRS AGO AN AIRLINER B747 STRUCK LIGHT STANCHIONS OFF THE DEP END OF RWY 1R IN A LATE-ROTATION ACCIDENT; IN SIMILAR CIRCUMSTANCES. SFO OFTEN STRETCHES WX AND WIND LIMITS TO THE MAX IN ORDER TO KEEP TFC FLOWING. I DO NOT KNOW WHAT FORMAL ATC POLICY IS REGARDING ISSUANCE OF WIND INFO IN CONJUNCTION WITH TKOF CLRNCS. HOWEVER; CONCEALING THIS KIND OF INFO FROM PLTS COULD LEAD TO A DISASTER.

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