Q: When an airplane is slowing after touching down, how much of the stopping power is coming from the engines, as opposed to the brakes?
A: When we are slowing the aircraft down after landing, the majority of our stopping power is coming from the brakes, not the reverse thrust on the engines. Our aircraft are actually certified to operate without thrust reversers, which provide an extra level of safety but are not required to bring the aircraft to a safe and complete stop.
The brake system is hydraulically powered, with normal and alternate braking systems. The normal brake system is applied manually through conventional brake pedal inputs, much like a car. For landing in adverse weather, on very short or slippery runways, all United aircraft are equipped with the added safety feature of an auto-braking system, which applies brakes immediately upon the wheels touching down. Additionally, part of the brake system on all aircraft includes an anti-skid system. Just like in cars, this system reduces pressure as needed to prevent skidding, wheel lockup and hydroplaning during adverse conditions.
Captain James T. Simons Jr. is United’s Washington Dulles chief pilot.
Do you have a question for Captain James T. Simons Jr.? You can write to him at firstname.lastname@example.org