Narrative:

Our crew had thorough takeoff brief for runway 28L at the gate. Approaching hold line for runway 28L; tower asked if we had numbers for runway 28R. First officer advised we had numbers; tower cleared us across runway 28L; position and hold runway 28R. I asked first officer to install runway 28R and said to check legs page and to close route discon. He also entered assumed temperature for runway 28R off data sheet he printed at the gate. Shortly; we were cleared for takeoff. We began roll and at 80 KT call. I crosschecked EPR and noticed a lower than expected EPR; temperature of 55 degrees. I queried first officer about temperature and he replied it was correct temperature. The acceleration seemed a little slow; but we rotated at normal distance at or after intersection of runway 1L. The thrust setting seemed lower than normal; but we continued on climb out. Above FL180 I reviewed the takeoff data sheet for runway 28R and noted the 55 degree assumed temperature. On closer review if found TOGW to be 457.8. With that temperature setting; the atgw was 4877. Our actual TOGW was 567.7. We reviewed the uplink messages for both runways and confirmed the discrepancies. The first officer had requested the takeoff data for runway 28L shortly after arriving at aircraft. 3 mins later he requested data for runway 28R. We briefed the data for runway 28L but didn't look at the data for runway 28R since we were planning for the left and it was more restrictive. Therefore; not noting the large difference between assumed temperatures. The first officer properly deleted the TOGW entry when requesting data for runway 28L; but must have missed this step when requesting weights for runway 28R. As these requests were made during fueling; the system must have defaulted to the gw generated by the actual amount of fob; yielding erroneous data. The first officer tried to be as thorough as possible after changing the runway entry. I should have caught the mistake earlier; but assumed the data had been reviewed. In retrospect; any data requested should be reviewed by all crew members as it is received; to help short notice changes go smoothly. We attempted to help ATC by accepting a different and longer runway; but in our haste; we made a serious error. An error that our 4 man crew should have caught earlier. Bottom-line; don't make changes in a critical phase. Stop; check the data; load it; and then accept takeoff clearance. At the time; I didn't think that we were too rushed; but; apparently we were.

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Original NASA ASRS Text

Title: A B777-200 DPTED SFO USING AN ASSUMED TEMP FOR A TOGW 80000 LBS TOO LIGHT.

Narrative: OUR CREW HAD THOROUGH TKOF BRIEF FOR RWY 28L AT THE GATE. APCHING HOLD LINE FOR RWY 28L; TWR ASKED IF WE HAD NUMBERS FOR RWY 28R. FO ADVISED WE HAD NUMBERS; TWR CLRED US ACROSS RWY 28L; POS AND HOLD RWY 28R. I ASKED FO TO INSTALL RWY 28R AND SAID TO CHK LEGS PAGE AND TO CLOSE RTE DISCON. HE ALSO ENTERED ASSUMED TEMP FOR RWY 28R OFF DATA SHEET HE PRINTED AT THE GATE. SHORTLY; WE WERE CLRED FOR TKOF. WE BEGAN ROLL AND AT 80 KT CALL. I XCHKED EPR AND NOTICED A LOWER THAN EXPECTED EPR; TEMP OF 55 DEGS. I QUERIED FO ABOUT TEMP AND HE REPLIED IT WAS CORRECT TEMP. THE ACCELERATION SEEMED A LITTLE SLOW; BUT WE ROTATED AT NORMAL DISTANCE AT OR AFTER INTXN OF RWY 1L. THE THRUST SETTING SEEMED LOWER THAN NORMAL; BUT WE CONTINUED ON CLBOUT. ABOVE FL180 I REVIEWED THE TKOF DATA SHEET FOR RWY 28R AND NOTED THE 55 DEG ASSUMED TEMP. ON CLOSER REVIEW IF FOUND TOGW TO BE 457.8. WITH THAT TEMP SETTING; THE ATGW WAS 4877. OUR ACTUAL TOGW WAS 567.7. WE REVIEWED THE UPLINK MESSAGES FOR BOTH RWYS AND CONFIRMED THE DISCREPANCIES. THE FO HAD REQUESTED THE TKOF DATA FOR RWY 28L SHORTLY AFTER ARRIVING AT ACFT. 3 MINS LATER HE REQUESTED DATA FOR RWY 28R. WE BRIEFED THE DATA FOR RWY 28L BUT DIDN'T LOOK AT THE DATA FOR RWY 28R SINCE WE WERE PLANNING FOR THE L AND IT WAS MORE RESTRICTIVE. THEREFORE; NOT NOTING THE LARGE DIFFERENCE BTWN ASSUMED TEMPS. THE FO PROPERLY DELETED THE TOGW ENTRY WHEN REQUESTING DATA FOR RWY 28L; BUT MUST HAVE MISSED THIS STEP WHEN REQUESTING WTS FOR RWY 28R. AS THESE REQUESTS WERE MADE DURING FUELING; THE SYS MUST HAVE DEFAULTED TO THE GW GENERATED BY THE ACTUAL AMOUNT OF FOB; YIELDING ERRONEOUS DATA. THE FO TRIED TO BE AS THOROUGH AS POSSIBLE AFTER CHANGING THE RWY ENTRY. I SHOULD HAVE CAUGHT THE MISTAKE EARLIER; BUT ASSUMED THE DATA HAD BEEN REVIEWED. IN RETROSPECT; ANY DATA REQUESTED SHOULD BE REVIEWED BY ALL CREW MEMBERS AS IT IS RECEIVED; TO HELP SHORT NOTICE CHANGES GO SMOOTHLY. WE ATTEMPTED TO HELP ATC BY ACCEPTING A DIFFERENT AND LONGER RWY; BUT IN OUR HASTE; WE MADE A SERIOUS ERROR. AN ERROR THAT OUR 4 MAN CREW SHOULD HAVE CAUGHT EARLIER. BOTTOM-LINE; DON'T MAKE CHANGES IN A CRITICAL PHASE. STOP; CHK THE DATA; LOAD IT; AND THEN ACCEPT TKOF CLRNC. AT THE TIME; I DIDN'T THINK THAT WE WERE TOO RUSHED; BUT; APPARENTLY WE WERE.

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.