Aircraft are equipped with brakes, but the devices and the moments they are used differ from those on road vehicles. Most wheels carry hydraulically activated disc brakes - heavy-duty counterparts of automobile units - whose friction halts the machine during taxi and the ground-roll after touchdown.
To stop the airplane completely, pilots combine three resources: the drag naturally produced by the wings, the wheel brakes, and the reverse thrust from the engines. Large or fast machines deploy air-brake surfaces in flight to increase drag and control speed on approach, yet these are not part of the ground-braking sequence.
Expert behind this article
Jim Goodrich
Jim Goodrich is a pilot, aviation expert and founder of Tsunami Air.
Do airplanes have brakes?
Yes, airplanes have brakes. The wheels of most aircraft have brakes, and these disc brakes squeeze the wheels, thereby slowing down the speed at which they spin. Aircraft disc brakes are used to brake the wheels while touching the ground and are operated hydraulically, pneumatically or electrically. Early aircraft transmission of the brake control input to the braking device was mechanical, but today's systems provide enough braking friction to reliably stop the airplane.
Brakes are used for taxiing and sometimes for landing. Pilots can use differential braking capability to steer the aircraft on the ground. Some aircraft over the years had nose wheel brakes. Aircraft braking systems must be able to reliably stop the aircraft in the event of a rejected takeoff or other emergency situation, and certification requires that the braking system of an aircraft has the ability to stop an aircraft at maximum certified takeoff weight with reject initiated at decision speed.
In addition to wheel brakes, many planes are fitted with air brakes. Air brakes increase drag on the aircraft when extended into the airstream and are used to increase drag on the aircraft. Jet-powered aircraft must use air brakes to control speed and descent angle during landing approach, while propeller-driven aircraft benefit from the natural braking effect of the propeller when engine power is reduced to idle. Jet airplanes commonly use thrust reversers and flaps to maximize the function of the wheel brakes.
Where are the brakes located in a plane?
Aircraft brakes are almost exclusively located on the main wheels installed under the fuselage and main wings. Each brake unit sits at the center of its tire. The nose and tail wheels do not have brakes. In small planes two hydraulic brake assemblies are fitted, whereas a 787 carries one brake unit on each of the eight wheels of the main gear assembly.
The pilot and copilot operate these brakes with their feet. Brake controls are located in the rudder pedals: the top section of either the left or right pedal activates the brake on the respective side's main wheel. Pressing the top of both pedals together gives normal braking whereas pressing only one side creates differential braking for tight turns. In most modern aircraft this toe-brake action sends an electrical signal from the flight deck to hydraulic actuators near the main landing gear, which then squeeze carbon discs against the wheel. Electromechanically activated brakes replace hydraulic lines with cables, and electrically powered actuators press stators - flat plates covered in wearable brake lining - against the rotors to generate friction.
Besides the toe brakes, planes carry an emergency or parking brake, a lever in the cockpit that actuates the same brake system. Smart monitoring features let engineers read brake temperature and real-time wear on the carbon disks through the wheel synoptic page, assuring the brakes remain ready for every landing roll.
How do breaks in a plane work?
Breaks work by using disc brakes mounted on wheels. A Cessna 172 uses a single-disc system. Disc brakes will remain static and stationary as the wheels turn, but when the pilot steps on the brake pedal the caliper presses the pads against the disc. This pressing of disks causes friction, and friction increases so the brake stops motion and slows wheel speed. Brakes rely on strong materials and precise mechanics to perform reliably. In the past, steel was used to make the brakes.
Foot-operated controls allow the pilot to apply left or right brakes independently, so differential braking maintains directional control during rollout. Hydraulic fluid transmits the pedal force; if one system fails, the other takes over, but leaking hydraulic fluid means the brake system has lost the fluid it needs. While in flight, an airplane can slow down by reducing thrust. Dive brakes are needed to prevent the airplane from building up too much speed, and pushing the tires down reduces the lifting force of the airplane.
How does a plane brake when landing?
A brake during landing works in three synchronized stages that begin the moment the landing gear touches the runway. First, wing spoilers attached to the back of the wings raise; by stopping the wing from creating lift, they press the tyres hard against the asphalt so that the next two systems can grip. Second, hydraulic fluid rushes through rigid lines into disc-brake housings on each landing-gear strut. These disc brakes vary clamping force with landing speed and slow the wheels. Third, while the spoilers and brakes are working, pilots engage thrust reversers that change engine airflow direction. The reversers redirect the jet blast forward instead of backward, generating deceleration that is especially needed on wet or slippery runways. Reverse thrust, disc brakes, and raised spoilers together create the most potent post-touchdown braking effect, turning a touchdown speed of roughly 160-170 mph (257-274 km/h) into a safe taxi speed within a few thousand feet.
How does a plane brake in the air?
To employ a brake in air, a pilot actuates the speed-brake lever. This command sends hydraulic pressure to every flight-spoiler panel, which rises symmetrically into the slipstream. Because spoilers cut off lift and, at the same time, expose a larger surface to the airflow, they cause an immediate increase in drag on the aircraft. The combination of lost lift and added drag produces a controlled deceleration without any need for wheel brakes, letting the airplane shed speed quickly while remaining stable in the air.
