![Takeoff weight diagram](https://upload.wikimedia.org/wikipedia/commons/a/af/Takeoff_weight_diagram.svg)
The maximum takeoff weight (MTOW) or maximum gross takeoff weight (MGTOW) or maximum takeoff mass (MTOM) of an
aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...
is the maximum weight at which the pilot 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.
MTOW is the heaviest weight at which the aircraft has been shown to meet all the
airworthiness
In aviation, airworthiness is the measure of an aircraft's suitability for safe flight. Initial airworthiness is demonstrated by a certificate of airworthiness issued by the civil aviation authority in the state in which the aircraft is register ...
requirements applicable to it. 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.
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.
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; 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.
Multiple MTOW
It is possible to have an aircraft certified with a reduced MTOW, lower than the structural maximum, to take advantage of lower MTOW-based fees, such as insurance premiums, landing fees and air traffic control fees are MTOW based.
This is considered a permanent modification.
Alternatively, holders of an Air Operator Certificate (AOC) may vary the Maximum Declared Take-Off Weight (MDTOW) for their aircraft. They can subscribe to a scheme, and then vary the weight for each aircraft without further charge.
[https://publicapps.caa.co.uk/modalapplication.aspx?appid=11&mode=detail&id=3583][https://www.caa.co.uk/commercial-industry/aircraft/operations/aircraft-insurance/]
An aircraft can have its MTOW increased by reinforcement due to additional or stronger materials. For example, the
Airbus A330
The Airbus A330 is a wide-body aircraft developed and produced by Airbus.
Airbus conceived several derivatives of the A300, its first airliner in the mid-1970s. Then the company began development on the A330 twinjet in parallel with the A340 ...
242 tonnes MTOW variant /
A330neo
The Airbus A330neo ("neo" for " New Engine Option") is a wide-body airliner developed by Airbus from the Airbus A330 (now A330''ceo'' – "Current Engine Option"). A new version with modern engines comparable with those developed for the Boei ...
uses
Scandium–aluminium (scalmalloy) to avoid an
empty weight The empty weight of a vehicle is based on its weight without any payload (cargo, passengers, usable fuel, etc.).
Aviation
Many different empty weight definitions exist. Here are some of the more common ones used.
GAMA standardization
In 1975 ...
increase.
Metal 3D Printing Material Scalmalloy Could be the Aircraft Material of the Future. 3DPrint.com, Sarah Saunders. Jul 20, 2018.
/ref> Smaller aircraft like the Cessna 208 Caravan
The Cessna 208 Caravan is a utility aircraft produced by Cessna.
The project was commenced on November 20, 1981, and the prototype first flew on December 9, 1982.
The production model was certified by the Federal Aviation Administration, FAA ...
may have an option for a reinforced undercarriage to permit an 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
A flap is a high-lift device used to reduce the stalling speed of an aircraft wing at a given weight. Flaps are usually mounted on the wing trailing edges of a fixed-wing aircraft. Flaps are used to reduce the take-off distance and the landing ...
setting. See the Spanair Flight 5022
Spanair Flight 5022 was a scheduled domestic passenger flight from Barcelona–El Prat Airport to Gran Canaria Airport, Spain, via Madrid–Barajas Airport that crashed just after take-off from runway 36L at Madrid Airport at 14:24 CES ...
crash
* 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
* ICAO recommendations on use of the International System of Units
* Aircraft gross weight
The aircraft gross weight (also known as the all-up weight and abbreviated AUW) is the total aircraft weight at ''any moment'' during the flight or ground operation.
An aircraft's gross weight will decrease during a flight due to fuel and oil co ...
* List of airliners by maximum takeoff weight
This is a list of aircraft sorted by maximum takeoff weight.
Airplanes
MTOW = Maximum take-off weight, MLW = Maximum landing weight, TOR = Take-off run ( SL, ISA+15°, MTOW), LR = Landing run (SL, ISA+15°, MLW)
Helicopters
MTOW = Maximum take- ...
* Maximum zero-fuel weight
In mathematical analysis, the maxima and minima (the respective plurals of maximum and minimum) of a function (mathematics), function, known collectively as extrema (the plural of extremum), are the largest and smallest value of the function, e ...
* Operating empty weight
Empty weight (EW) is the sum of the ‘as built’ manufacturer's empty weight (MEW), plus any standard items (SI) plus any operator items (OI), EW = MEW + SI + OI. The EW is calculated for each aircraft series and each unique configuration of an a ...
* Wake turbulence category
Wake turbulence categories and wake turbulence groups are defined by the International Civil Aviation Organization for the purpose of separating aircraft in flight, due to wake turbulence.
Wake turbulence categories
Since 2020, there are four ca ...
References
{{reflist
External links
CAA data terms definition
Aircraft weight measurements