Narrative:

I was flying in the copilot seat on a B767 for a captain trainee. I am a company line check airman. We were taxiing for our takeoff on runway 4L at jfk. We were on taxiway kilo south of runway 31L. Our final weights had not been transmitted to us over ACARS, so I called company operations with our passenger count of 10/22/45 as provided by the first flight attendant. A few mins later, operations called to verify the passenger count in the mid-cabin. I responded with '22 passenger.' operations transmitted our final weights via ACARS and I entered the ZFW into the FMC. We completed our before takeoff checklist and were cleared for takeoff on runway 4L, while still taxiing to the runway. I sensed something was not quite right, but could not identify what was causing this feeling. After taking off and well into our climb out, it occurred to me. Our actual versus reported passenger count was off by 60. We had 60 less passenger than was reported on our final weight and balance. I sent a message to dispatch asking for a revised ZFW which was 10500 pounds less than the ZFW listed on the ACARS final weights. Even with the incorrect ZFW we were well below our maximum takeoff weight limits. The problem, as I see it, was that I was trying to be a good copilot, watch and instruct my student and accommodate ATC, plus I allowed myself to become rushed and accepted a clearance while there was doubt. I strive never to be rushed into doing something I am not ready to do. Lesson learned again!

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Original NASA ASRS Text

Title: FLC OF B767 MISCALCULATED TKOF WT BASED UPON INCORRECT PAX COUNT. ACFT DEPARTED WITH SPDS, AND PERFORMANCE BASED UPON INCORRECT INFO.

Narrative: I WAS FLYING IN THE COPLT SEAT ON A B767 FOR A CAPT TRAINEE. I AM A COMPANY LINE CHK AIRMAN. WE WERE TAXIING FOR OUR TKOF ON RWY 4L AT JFK. WE WERE ON TXWY KILO S OF RWY 31L. OUR FINAL WTS HAD NOT BEEN XMITTED TO US OVER ACARS, SO I CALLED COMPANY OPS WITH OUR PAX COUNT OF 10/22/45 AS PROVIDED BY THE FIRST FLT ATTENDANT. A FEW MINS LATER, OPS CALLED TO VERIFY THE PAX COUNT IN THE MID-CABIN. I RESPONDED WITH '22 PAX.' OPS XMITTED OUR FINAL WTS VIA ACARS AND I ENTERED THE ZFW INTO THE FMC. WE COMPLETED OUR BEFORE TKOF CHKLIST AND WERE CLRED FOR TKOF ON RWY 4L, WHILE STILL TAXIING TO THE RWY. I SENSED SOMETHING WAS NOT QUITE RIGHT, BUT COULD NOT IDENT WHAT WAS CAUSING THIS FEELING. AFTER TAKING OFF AND WELL INTO OUR CLBOUT, IT OCCURRED TO ME. OUR ACTUAL VERSUS RPTED PAX COUNT WAS OFF BY 60. WE HAD 60 LESS PAX THAN WAS RPTED ON OUR FINAL WT AND BAL. I SENT A MESSAGE TO DISPATCH ASKING FOR A REVISED ZFW WHICH WAS 10500 LBS LESS THAN THE ZFW LISTED ON THE ACARS FINAL WTS. EVEN WITH THE INCORRECT ZFW WE WERE WELL BELOW OUR MAX TKOF WT LIMITS. THE PROB, AS I SEE IT, WAS THAT I WAS TRYING TO BE A GOOD COPLT, WATCH AND INSTRUCT MY STUDENT AND ACCOMMODATE ATC, PLUS I ALLOWED MYSELF TO BECOME RUSHED AND ACCEPTED A CLRNC WHILE THERE WAS DOUBT. I STRIVE NEVER TO BE RUSHED INTO DOING SOMETHING I AM NOT READY TO DO. LESSON LEARNED AGAIN!

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.