Maximum Takeoff Weight


Maximum Takeoff Weight

The Maximum Takeoff Weight (MTOW) or Maximum Takeoff Mass of an aircraft is the maximum weight at which the pilot of the aircraft is allowed to attempt to take off, due to structural or other limits. The analogous term for rockets is Gross Lift-Off Mass, or GLOW. MTOW is usually specified in units of kilograms or pounds, but some aircraft manufacturers also use kilogram-force (kgf) or pound-force (lbF)[1].

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 weight the "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.

Contents

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 can meet 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 climbing at 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.

Takeoff weight components

Multiple MTOW

Among large airliners, the same model of aircraft can have more than one MTOW. An airline can choose to have its airliner 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 [2]).

In many examples, such as the Cessna 208 Caravan, the increased MTOW option generally consists of a reinforced undercarriage. There are other aircraft such as the Cessna 206 which offers a Heavy Undercarriage option at time of purchase, but comes with no such increase in MTOW.

Maximum permissible takeoff weight or Maximum allowed takeoff weight

In many circumstances an aircraft may not be permitted to take off at its MTOW. In these circumstances the maximum weight permitted for takeoff will be determined taking account of the following:

  • Wing flap setting. See the Spanair Flight 5022
  • Airfield altitude (height above sea-level) - This affects air pressure which affects maximum engine power or thrust.
  • Air temperature - This affects air density which affects maximum engine power or thrust.
  • Length of Runway - A short runway means the aircraft has less distance to accelerate to takeoff speed. The length for computation of maximum permitted takeoff weight may be adjusted if the runway has clearways and/or stopways.
  • Runway wind component - The best condition is a strong headwind straight along the runway. The worst condition is a tailwind. If there is a crosswind it is the wind component along the runway which must be taken into account.
  • Condition of Runway - The best runway for taking off is a dry, paved runway. An unpaved runway or one with traces of snow will provide more rolling friction which will cause the airplane to accelerate more slowly. See the Munich Air Disaster
  • Obstacles - An airplane must be able to take off and gain enough height to clear all obstacles and terrain beyond the end of the runway.

The maximum weight at which a takeoff may be attempted, taking into account the above factors, is called the maximum permissible takeoff weight, maximum allowed takeoff weight or regulated takeoff weight.

See also

External links

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • maximum takeoff weight — The maximum gross weight, as a result of design or operational limitations, at which an aircraft is permitted to takeoff …   Aviation dictionary

  • List of airliners by Maximum Takeoff Weight — This is a list for civilian airliners (including army civilian cargos, so C 5 Galaxy is excluded) sorted by Maximum Takeoff Weight. Considering there are many projects featuring large airliners, this list focus on the built and operational… …   Wikipedia

  • Maximum Landing Weight — The Maximum Landing Weight (MLW) is the maximum aircraft gross weight due to design or operational limitations at which an aircraft is permitted to land. It must not exceed the maximum takeoff weight (MTOW). The operation landing weight may be… …   Wikipedia

  • Maximum Ramp Weight — The Maximum Ramp Weight (MRW) (also known as the Maximum Taxi Weight (MTW)) is the maximum weight authorised for manoeuvring (taxiing or towing) an aircraft on the ground as limited by aircraft strength and airworthiness requirements. It includes …   Wikipedia

  • maximum landing weight — The greatest weight an aircraft is allowed to have for landing. It is often less than the maximum takeoff weight, and the pilot may have to dump fuel or jettison some stores before executing a landing shortly after takeoff. A landing with a… …   Aviation dictionary

  • Maximum Zero-Fuel Weight — 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 flying at a weight of 5,000 lb and the weight of fuel on board is …   Wikipedia

  • takeoff distance required — i. The horizontal distance required to accelerate from a standing start with all engines operating to achieve a safety speed at a height of 50 ft above the takeoff surface, multiplied by 1.15 for airplanes with a maximum takeoff weight of 4500 lb …   Aviation dictionary

  • Takeoff — is the phase of flight in which an aircraft goes through a transition from moving along the ground (taxiing) to flying in the air, usually starting on a runway. For balloons, helicopters and some specialized fixed wing aircraft (VTOL aircraft… …   Wikipedia

  • flexible takeoff — A type of takeoff in which less than the maximum thrust is selected because the takeoff weight for that flight is less than the maximum takeoff weight …   Aviation dictionary

  • landing weight — The weight of an aircraft on touch down. It is often limited and is less than the maximum takeoff weight. Most aircraft have a provision for jettisoning or dumping fuel to bring the aircraft within a specified maximum weight for landing. Landing… …   Aviation dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.