Definition
The greatest weight at which an aircraft is certificated and approved to begin its takeoff roll, as established by the manufacturer and listed in the aircraft's type certificate and pilot's operating handbook. It includes the airframe, engines, fuel, oil, occupants, baggage, and any cargo on board at the moment takeoff power is applied.
Plain English
The heaviest the aircraft is allowed to be when it starts its takeoff. If the total weight of the plane plus everything and everyone in it is above this number, the aircraft is not legal or safe to take off.
Context Anchor
Seen in aircraft loading, performance planning, and light-sport aircraft eligibility discussions.
Derivation
Maximum comes from the Latin maximus, meaning greatest. In this term, it points to an upper limit: the airplane may weigh less than this for takeoff, but not more.
Why Pilots Care
Exceeding this limit increases stall speed, lengthens the takeoff roll, reduces climb performance, and can make the flight unsafe or illegal.
Intuition Check
Do not read maximum takeoff weight as the airplane's normal weight on every takeoff. It means the upper allowed limit for starting takeoff.
Example Sentence 1
After loading the bags and adding fuel, she recalculated the weight and confirmed the airplane was 40 pounds below its maximum takeoff weight.
Example Sentence 2
For this light-sport aircraft the maximum takeoff weight is listed as 1320 pounds in the operating handbook.