What is MTOW?
Maximum Take-off Weight – or MTOW – is the maximum certified weight at which a commercial aircraft is allowed to attempt a take-off. It is often provided in kilograms or pounds. MTOW is also sometimes referred to as Maximum Gross Take-off Weight or Maximum Take-off Mass.
The MTOW is the highest weight at which an aircraft has been certified to meet all of its airworthiness requirements, and is a fixed value for that given aircraft model. It does not vary based on an airport’s runway or the environmental conditions. However, limitations in the airport’s runway or other infrastructure – or other operational concerns – may limit the actual payload the aircraft is permitted to take-off at.
The MTOW is arrived at by adding the weight of traffic load (passengers, passenger baggage, cargo) plus the trip fuel and reserve fuel to the Operating Empty Weight (OEW) of an aircraft and is determined by the aircraft manufacturer during the aircraft model’s certification process. Adding the taxi fuel amount to the above equation provides an aircraft’s Maximum Taxi Weight.
Multiple MTOWs of same aircraft model
The same aircraft model could have multiple MTOWs assigned to different sub-models of it. This is to optimize the aircraft for the various range/ payload specific missions that the aircraft will be used by operators and is known as the different ‘weight variants’ of the aircraft model.
The weight variants could both be driven by operational requirements, as well as due to an aircraft’s continuous development over the years.
An example which you can see at the Airbus aircraft MTOW specs page is the different weight models in which the Airbus A330-300 is available.
Of these, the 184t MTOW model is the initial model which the aircraft was introduced to the market with – and included a limited range. As the aircraft evolved over the years, its MTOW was increased to the 230t range. As of today, the A330-300 is certified at a highest MTOW of 242t – which is driven by an operational requirement to fly longer missions.