it also takes a really long time. it must be measured accurately. a lot of airports and airplane companies will not allow passengers on the plane when transfering fuel.

if you check max takeoff weight and landing weight, for a 767, 450000-350000lbs=100,000lbs. that's a lot of gas. at less than 7 lbs/gal, that's about 15,000 gallons. a fully loaded tank truck that is on the road carries about 8000 gal. so you are looking at 2 tank trucks.

on 2 occasions, we had to get off the plane for fueling. once at iad, and once somewhere in italy(all italian airports look the same).