3 ms·

It appears so: "As a result, the aircraft departed with a takeoff weight 1,244 kg more than stated on the load sheet." If 50 women weigh 94 kg instead of the

It appears so: "As a result, the aircraft departed with a takeoff weight 1,244 kg more than stated on the load sheet." If 50 women weigh 94 kg instead of the assumed 69 kg, that difference is also reached. I'm surprised that the 737 has such a low error tolerance.

shadowgovt 6y ago
>low error tolerance In a sense, it's not too terribly low; the end result here was that the plane took off outside of the correct flight envelope but well within a safe and controllable envelope (given a loading difference that - back of the napkin calculation - is 2% of its dry weight). But AAIB pursues this sort of thing aggressively, under the principle of "Don't assume everything is safe because the O-rings didn't fail if the O-rings are showing not-understood ablation."
johntb86 6y ago
The plane took off without a problem, so this was within the error tolerance. You could imagine cases (e.g. charter flights full of women) where it could be an issue, though.
sokoloff 6y ago
It has enormous margin during all-engine takeoff performance, so it's not at all surprising that the takeoff continued successfully. The performance calcs are done to ensure safety in a one-engine inoperative case. The performance calculations for all multi-engine turbojets require at least a balanced field (simplified meaning: that you can experience an engine failure at the most adverse moment in the takeoff sequence and either bring the aircraft to a halt on the runway surface [including EMAS or other stopway surface] or you can continue the takeoff and meet initial obstacle clearance and second stage climb requirements with the most adverse engine inoperative and maximum thrust from the working engine). That's why this is a serious deviation, even though turbofan engines rarely fail. 737s do reduced power takeoffs as a matter of economic optimization. The error here caused too little power to be commanded during the takeoff.

shadowgovt 6y ago

>low error tolerance In a sense, it's not too terribly low; the end result here was that the plane took off outside of the correct flight envelope but well within a safe and controllable envelope (given a loading difference that - back of the napkin calculation - is 2% of its dry weight). But AAIB pursues this sort of thing aggressively, under the principle of "Don't assume everything is safe because the O-rings didn't fail if the O-rings are showing not-understood ablation."

johntb86 6y ago

The plane took off without a problem, so this was within the error tolerance. You could imagine cases (e.g. charter flights full of women) where it could be an issue, though.

sokoloff 6y ago

It has enormous margin during all-engine takeoff performance, so it's not at all surprising that the takeoff continued successfully. The performance calcs are done to ensure safety in a one-engine inoperative case. The performance calculations for all multi-engine turbojets require at least a balanced field (simplified meaning: that you can experience an engine failure at the most adverse moment in the takeoff sequence and either bring the aircraft to a halt on the runway surface [including EMAS or other stopway surface] or you can continue the takeoff and meet initial obstacle clearance and second stage climb requirements with the most adverse engine inoperative and maximum thrust from the working engine). That's why this is a serious deviation, even though turbofan engines rarely fail. 737s do reduced power takeoffs as a matter of economic optimization. The error here caused too little power to be commanded during the takeoff.