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Maximum RunwayTake-off Weight (MRTW)

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General Aviation

What are MRTW and the one letter limiting factor code that follows MRTW? Is a list of codes available anywhere?

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2 Answers



  1. Matthew Mannfolk on Dec 09, 2017

    MRTW stands for Maximum Runway Takeoff Weight. This is the maximum allowable weight that an airplane can be in order to successfully takeoff from that specific runway. Since this is a runway-specific limitation, usually the MRTW will include a limiting factor that explains the most limiting reason for the MRTW for a given runway.

    In general, airplanes have a Maximum Takeoff Weight and that is the maximum structural loading that the airplane itself can take. This is the typical limitation that all pilots must memorize for their specific airplane and in the GA world, this is all one needs to know.

    MRTW is typically computed for larger airplanes because larger airplanes can vary quite wildly in the actual weight that they are currently loaded with and thus, their takeoff performance parameters can vary wildly as well. If a given large airplane can takeoff with a max of 50,000 lbs but only has 40,000 lbs on board, this will make a large difference in how much runway distance it will need and how well it can climb. Because is this variance, MRTW values are calculate stating the maximum weight an airplane can takeoff with given the available runway distance and initial climb area. As long as an airplane weighs less than the MRTW, the airplane is ok to depart

    An example of how MRTW changes would be a mountainous vs non-mountainous airport. Given the same runway distance available, because there are mountains surrounding one airport and not the other, the MRTWs for the mountainous airport\’s runways would be LESS than the MRTWs for a non-mountainous because with obstacles near the runway, an airplane would need to climb faster to avoid them and would not be able to take as much weight as the runway with no obstacles in the departure area.

    In the case above, in addition to a reduced MRTW, a limiting code would be included stating that the most limiting factor in the MRTW calculation would be due to the CLIMB required. Each aircraft manufacturer / operator would have their own specific list of codes but they all have the same basic factors

    Here is a link to an example list of limiting factor codes:
    https://www.flyapg.com/wp-content/uploads/2017/05/Intro.pdf

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  2. Charles22 on Dec 11, 2017

    Matthew,

    Many thanks for your detailed answer!

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