To Midland63,
I enjoyed reading your post and for a self-proclaimed 'non-pilot', you seemed to hit the nail on the head. The big question is, why did the aircraft get airborne so late? I have no idea, and the theories put forth are just speculation at this point.
As for 'cocking-up' the takeoff figures, it is not as uncommon as you might think. This is the reason EK has instituted back-up procedures such as gross error checks. The final check, which should eliminate a large error in weight inputted into the computer, is the crosscheck of Green Dot speed. Unfortunately, if the weight entered into the laptop, is the same as the weight showing on the MCDU, then these speeds will still match (even if this weight is not an accurate reflection of the aircrafts true weight) This gross error check only shows a difference when the MCDU and laptop weights do not match.
The method I use to avoid this trap, is to cross reference the MCDU weight with the preplanned CFP (computerized flight plan) weight. The moment I see a difference, I investigate further and it should be explainable by a change in ZFW plus a change in Ramp Fuel. I go so far, as doing the math and make sure even a change as small as 500kgs, adds up.
The added benefit of cross-checking the CFP takeoff weight, is that it precludes 'forgetting' to input the Final ZFW into the MCDU after we receive it. (initially the ZFW is entered as the estimated ZFW)
The trap here, is that we have several things to do after we receive the FZFW.
1-We have to determine the final fuel load based on this new number, which again will change the takeoff weight
2-We have to send this info via ACARS to CLC (centralized load control in Dubai)
3-We have to give the final fuel load to the engineer, who could be ANYWHERE around the plane doing other duties.
4-We usually have to give this info to the ramp agent as well (who could be ANYWHERE as well)
5-Most importantly, we have to enter the new weight in the MCDU or all our figures will be in error. (perhaps I should have made this duty #1)
Someone mentioned it earlier... many, many people with their own priorities are popping into the cockpit during this time frame, so sometimes we get distracted. We are human beings.
I am not suggesting this was the cause of the problem because there are not enough facts. I just wanted to point out that it is VERY possible to make errors because the procedures in place are not good enough. I hope EK adds this final check that I use, even if it had nothing to do with that takeoff out of MEL.