B737 Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 141; Flight Crew Type 2434
Situational Awareness
Deviation / Discrepancy - Procedural Weight And Balance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR
General None Reported / Taken
Human Factors; Procedure
Before push back we received our final weights and then pushed back for departure as per SOP. While taxiing to the runway; we received no less than four final weight adjustments. This was a distraction in attempting to sort out the actual weight and performance of the aircraft while attempting to accomplish pre departure duties. The last Zero Fuel Weight (ZFW) was 134.0. We were then cleared for takeoff and were satisfied with the weight and performance of the aircraft. The takeoff roll seemed a little long and the rotation was achieved with about 2; 500 feet left on a 10;500 foot runway.Seven minutes after departure we received another update on our final weights. The weight increase was 3;500 Lbs. to ZFW of 137.5. We did the performance for a ZFW of 134.0 not 137.0. I believe the problem with this is obvious.
[Seven] minutes after takeoff; around 10;000 feet; we received an ACARS message giving us yet again; a new set of final weights with Zero Fuel Weight (ZFW) 137. This was an increase of 3;500 LBS with approximately 20 more passengers listed on the final weights. This post takeoff final weight increase caused us to use inaccurate and inadequate runway takeoff performance data. We contacted load planning and Dispatch via ACARS to confirm this new ZFW and PAX count. Once they confirmed; we manually loaded [the revisions] into the FMC for use during the remainder of the flight.
B737 flight crew reported receiving 'final weights' about seven minutes after takeoff; showing an increase of 3;500 LBS.