Queenslander, most 747 freighters have a weight and balance computer fitted. The system weighs the airplane, computes the centre of gravity of the airplane and displays the gross weight and the MAC on indicators on P4 Flight Engineer's panel. The indications are cross checked against the load sheet and have to meet certain tolerances before flight. There are 18 weight sensors located in the landing gear axels, one for each wheel and an attitude sensor which senses the longitudinal attitude angle of the airplane. My last nine years of aviation career was spent operating 747-200F aircraft.