Zero Fuel Weight

Zero Fuel Weight (ZFW) is the total weight of the aircraft including its operating empty weight (structure, systems, crew, catering, supplies) plus all payload (passengers, baggage, cargo), but excluding all usable fuel. It is one of the four critical weight limitations in aircraft operations (along with Maximum Takeoff Weight, Maximum Landing Weight, and Maximum Ramp Weight).

The Maximum Zero Fuel Weight (MZFW) is a structural limitation that protects the wing root from excessive bending loads. During flight, the weight of fuel stored in the wings counterbalances the lift forces, reducing the bending moment at the wing root. If too much weight is concentrated in the fuselage (payload) without sufficient wing-stored fuel to counterbalance it, the wing root experiences excessive stress.

In practical terms: an aircraft at MZFW must carry any additional weight (up to MTOW) as fuel in the wing tanks. This means that on short flights where fuel load is light, the payload may be limited by MZFW rather than by MTOW — a common scenario for cargo operators.