The Maximum Takeoff Weight (MTOW) or Maximum Takeoff Mass of an aircraft or rotorcraft is the maximum weight atwhich the pilot of the aircraft is allowed to attempt to take off, due to structural or other limits.
MTOW is the heaviest weight at which the aircraft has been shown to meet all the airworthiness requirements applicable to it. MTOW of an aircraft is fixed, and does not vary with altitude or air temperature or the length of the runway to be used for takeoff or landing. A different weightthe "maximum permissible takeoff weight", or "regulated takeoff weight", varies according to flap setting, altitude, air temperature, length of runway and other factors. It is different from one takeoff to the next, but can never be higher than the MTOW.
Among large airliners, the same model of aircraft can have more than one MTOW. An airline can choose to have itsairliner certified for an increased weight at an additional cost. Some airlines which do not require a high MTOW choose to have a lower MTOW for that particular aircraft to reduce costs (Landing and air traffic control fees being MTOW based .
In many examples, such as the Cessna 208 Caravan, the increased MTOW generally consists of a reinforced undercarriage. There are other aircraft such as theCessna 206 which offers a Heavy Undercarriage option at time of purchase, but comes with no such increase in MTOW.
Certification standards Certification standards applicable to the airworthiness of an aircraft contain many requirements. Some of these requirements can only be met by specifying a maximum weight for the aircraft, and demonstrating that the aircraft canmeet the requirement at all weights up to, and including, the specified maximum. These requirements include: structural requirements - to ensure the aircraft structure is capable of withstanding all the loads likely to be imposed on it during maneuvering by the pilot, and gusts experienced in turbulent atmospheric conditions. performance requirements - to ensure the aircraft is capable of climbingat an adequate gradient with all its engines operating; and also with one engine inoperative. At the MTOW, all aircraft of a type and model must be capable of complying with all these certification requirements
The Zero Fuel Weight (ZFW) of an airplane is the total weight of the airplane and all its contents, minus the total weight of the fuel on board. For example, if an airplane is flyingat a weight of 5,000 lb and the weight of fuel on board is 500 lb, the Zero Fuel Weight is 4,500 lb. Some time later, after 100 lb of fuel has been consumed by the engines, the total weight of the airplane is 4,900 lb and the weight of fuel is 400 lb. The Zero Fuel Weight is still 4,500 lb. Note that, as a flight progresses and fuel is consumed, the total weight of the airplane reduces, but theZero Fuel Weight remains constant (unless some part of the load, such as parachutists or stores, is jettisoned in flight). For many types of airplane, the airworthiness limitations include a Maximum Zero Fuel Weight.
Maximum Zero-Fuel Weight: Is the maximum weight allowed before usable fuel and other specified usable agents (engine injection fluid, and other consumable propulsionagents) must be loaded in defined sections of the aircraft as limited by strength and airworthiness requirements. It may include usable fuel in specified tanks when carried in lieu of payload. The addition of usable and consumable items to the zero fuel weight must be in accordance with the applicable government regulations so that airplane structure and airworthiness requirements are not exceeded....