My understanding is that the amount of fuel loaded onboard the plane for takeoff by the ground crew is determined in part by this estimated weight figure. If t

My understanding is that the amount of fuel loaded onboard the plane for takeoff by the ground crew is determined in part by this estimated weight figure. If the weight estimate is too low, then it would be possible for the ground crew to load too little fuel, leading to a situation at the destination of nearly or actually running out of fuel. So it may have been labeled "serious" due to the possibility of not loading enough fuel if the weight estimates are too low by too much.