What defines the Max Runway Takeoff Weight (MRTW)?

• A. Lowest of weights, limited by: T/O runway length, climb/obstacle clearance, break energy, tire speed, AFM structural limits, en-route engine failure (drift down), landing runway length, go around
• B. The maximum certified takeoff weight
• C. The minimum takeoff weight permitted under taxi constraints
• D. The weight limited by fuel capacity only

Answer: (A)

MRTW is the weight you can safely take off with on a specific runway, determined by the most restrictive limit among all performance and certification constraints. In practice, you compare every factor that could cap takeoff weight—how long the runway is, the required climb and obstacle clearance, the braking energy needed to stop if you abort, tire speed limits, the aircraft’s AFM structural limits, engine-out (drift-down) performance, the available landing distance on the opposite runway, and the possibility of a go-around. The actual MRTW is the smallest of these limits, because you must satisfy every constraint at once. It isn’t just the maximum certified takeoff weight, and it isn’t a minimum under taxi or something limited only by fuel capacity. For example, even if the airplane could take off heavier from a different runway, the MRTW for this runway would drop to the value set by the most restrictive factor, such as obstacle clearance or braking requirements.