You report for brief and get a "plog" with a planned ZFW.
The weather, opdefs and notams folder info contains yet another ZFW
Then a "provisional" loadsheet is presented with another ZFW.
To which is added a fiddle-factor (+1,000kgs for the 737) and this is loaded into the FMS and used for takeoff perf, if the final and 5th ZFW passed by load control is within +1 ton or -2 tons of the original. If not "in compliance", then loading and perf and SID have to be done again on whatever taxiway/holding point before departure.
Having been exposed to FIVE different ZFWs, you now get airborne and somewhere up the climb when things are quiet, if having launched on the "fiddled" provisional weight/mass, then the real ZFW is loaded for cruise performance.
Perfectly normal stuff, all approved by the CAA, so that's all right then.
Don't bother to read the Boeing Magazine article on incorrect ZFW loading causing serious incidents/accidents, it no longer applies in this case.................................
