During a normal aircraft landing, the wheel brakes afford about 40% of the total braking energy.¹ The rest is assumed by aerodynamic braking (30%), reverse thrust of jet engines (20%), and rolling friction (10%). However, according to regulations of this transport sector, the wheel brakes must be able to stop the aircraft without support of any other braking system. This requirement must be fulfilled for loads generated at the maximal landing and rejected take-off speeds for maximum weight of the airplane.² Further, wheels and tires must not ignite nor explode, even in an emergency situation.

Stanton illustrated in 1968 the order of magnitude of braking loads generated during a rejected take-off, using a Douglas DC-8 Jet Trader as example.³ During this maneuver, the eight brake assemblies must deliver a total of 40,500 horsepower to stop the 163-ton aircraft at a velocity of 286 km/h (178 mph) in under 30 seconds. The kinetic energy absorbed by the braking system in this situation is similar to simultaneously braking 833 mid-sized passenger cars at a speed of 96 km/h (60 mph).