aviation

Maximum Ramp Weight

The heaviest weight an aircraft can be loaded to while on the ground, including all fuel, cargo, and passengers.

Maximum Takeoff Weight

The maximum weight an aircraft can be at the start of the takeoff roll, accounting for fuel burned during taxi.

Maximum Landing Weight

The maximum weight an aircraft is allowed to have when it lands, often much less than the maximum takeoff weight for large aircraft.

Maximum Zero Fuel Weight (MZFW)

The heaviest the aircraft can be loaded without any usable fuel; any extra weight above this must be fuel weight only.

Empty Weight

The weight of the aircraft as built, including structure and required operating fluids, but excluding usable fuel, passengers, and cargo.

Useful Load

The difference between the maximum allowable gross weight and the basic empty weight, including the crew, passengers, cargo, and usable fuel.

Empty Weight Center of Gravity (EWCG)

The center of gravity location of the aircraft based only on the empty weight, before adding crew, cargo, or fuel.

Tare Weight

The weight of any support equipment used during the weighing process, which must be subtracted to get the true weight.

Datum

A fixed imaginary vertical plane chosen by the manufacturer from which all horizontal measurements are taken for balance calculations.

Arm

The horizontal distance from the datum to the center of gravity of an item or load.

Moment

The product of a weight times its arm, used to simplify center of gravity calculations.

Undrainable Fuel

Small amounts of fuel that cannot be safely drained from the fuel system and must be accounted for in weight calculations.

Unusable Fuel

The amount of fuel that cannot be used during flight because it cannot be reliably fed into the engine.

Ballast

Weight added to the aircraft to bring the center of gravity within allowable limits.

ATA Chapter 8

The section in the Aircraft Technical Administration (ATA) codes that pertains to Weight and Balance.