Originally Posted by
rattman
181 when asked how many souls on board.
His Rattman
The number of passengers is nearly irrevant. They weigh so little compared to the big picture
747 MTOW 400 TONNES
MAX FUEL 180 TONNES
PASSENGERS/BAG 400 @ 100 KG = 40 TONNES
EMPTY WEIGHT 180 TONNES. = NO FUEL NO PASSENGERS
MAX LANDING WEIGHT (NORMALLY). 290 TONNES.
SO GET AIRBORNE AT 400 TONNES YOU NEED TO DUMP BACK TO 290 TONNES (PLANE WILL LAND WITH ITS OWN WEIGHT 180T + 40 T PASSENGERS + UP TO 50 T OF FUEL.
DUMPING THAT 110 TONNES. OF FUEL AT 2 TONNES PER MINUTE WOULD TAKE NEARLY AN HOUR.
But, and this is the point here, you can land at Max TOW (actually about 390 tonnes because you would burn ten tonnes on takeoff and circuit) if there is a serious emergency that does not permit fuel dumping (say fire) or due to serious damage which suggests getting back on the ground asap.
There is no commercial imperative to save money by not dumping
Cheers
RG