Maximum takeoff weight

MTOW is the heaviest weight at which the aircraft has been shown to meet all the airworthiness requirements applicable to it.

It refers to the maximum permissible aircraft weight at the start of the takeoff run.

[1] MTOW of an aircraft is fixed and does not vary with altitude, air temperature, or the length of the runway to be used for takeoff or landing.

[4] Alternatively, holders of an Air Operator Certificate (AOC) may vary the Maximum Declared Take-Off Weight (MDTOW) for their aircraft.

For example, the Airbus A330 242 tonnes MTOW variant / A330neo uses Scandium–aluminium (scalmalloy) to avoid an empty weight increase.