Originally Posted by
alexperi
I find it so hard to believe that passenger positions have any real bearing on balance. These planes weigh many many tons, they have all the baggage in the cargo - how can a few people moving a few yards back or forward here or there make any difference whatsoever? I'd be happy to be corrected on this and given the science, but it seems a little odd...
Small changes in the placement of the mass can make big differences in how the aircraft controls. Big jets normally have enough margin that passengers don't get moved around but it can happen. I second the other poster who suspects misloaded (or perhaps the cargo destined for the back didn't make it for some reason) cargo. Passengers move themselves, cargo doesn't--which is faster to fix?