What determines the maximum payload weight, as seen in the horizontal line of a payload-range diagram? I understand that

$ OEW + W_{fuel} + W_{payload} \leq MTOW$

but what's stopping me from just putting in 10lbs of fuel, enough to taxi across the apron, and therefore have a maximum payload weight of MTOW - OEW?


1 Answer 1


Aircraft also have a Maximum Zero-Fuel Weight (MZFW). This defines the aircraft's maximum weight without any fuel loaded. A large aircraft certainly would not be able to fly with only 10lb of fuel on board, so structures like the fuselage are designed to carry a lower payload.

For example, the Boeing 777F freighter has a maximum takeoff weight of 347,814kg. The type certificate lists the MZFW as 248,115kg, which leaves almost 100,000kg for fuel out of the max fuel capacity of 145,538kg. This is a large increase from the passenger version (777-200LR), which has a MZFW of 209,106kg with only slightly lower MTOW.

See also: What are different types of weights of an aircraft?


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