korrol, wouldn't you buy petrol for your car at a cheaper petrol station? This is common industry practice and bears no relationship to whether the operator is a low cost operator or flag carrier, it keeps the costs of your tickets down!
It is very clearly laid down in legislation the minimum fuel that can be carried and airlines have no option but follow the regulations. It's not as simple as just the fuel from "A" to "B", there has to be extra fuel for taxying the aircraft, diverting to another airfield, holding fuel, and a percentage extra "just in case" (contingency) plus fuel if you anticipate using extra fuel consuming devices (APU, anti-ice etc).
Very rarely on a large aircraft will the tanks be full at departure as the weight of fuel + passengers + aircraft could well exceed the maximum allowed take off weight of the aircraft, and at the other end if you have too much fuel, you could exceed the maximum allowed landing weight of the aircraft.
Last edited by Engine overtemp; 20th Feb 2011 at 10:49.