Originally Posted by
Globaliser
I'd be interested to hear from pilots whether a tonne would make any significant difference to the weights/speed/trim calculations.
The self-loading cargo isn't weighed, nor is the cargo that they schlep on board themselves, and the airline uses educated guesswork for this part of the payload. The 787-9 may have about 230 occupants when full. An average 5 kg error per person would be well over a tonne, yet there seems to be no hysteria about this possibility, which is simply just a known unknown.
In addition, does the 787-9 have stuff to help with trim once airborne, like shifting fuel about?
If the aircraft did depart without this being noticed, then it's pretty poor. And once airborne, the crew have to go through the same decision-making process about whether to live with a non-critical problem or to inflict a 24-hour delay on all the passengers as if the system had just broken down (as in other cases). But if it isn't a safety-of-flight issue, let's not go overboard about that.
Passengers' contribution to the payload is assessed as an average: and as with averages and large numbers, individual discrepancies tend to level out in the wash. Suggesting that because that final tally of passengers might be a little out, other payload miscalculations can be disregarded seems a tad, well, cavalier.
An additional tonne or so of payload is significant. I'm sure it's a manageable unknown, but it's another hole in that Swiss cheese.
It's something pilots would want to know about, expect to know about, before they leave.
In this case i simply hypothesise they did know.
I don't see any hysteria, nothing overboard: maybe a little fig-leaf repositioning in the response though
