Autobrake
Encyclopedia
An autobrake is a type of automatic wheel-based hydraulic brake
system for advanced airplanes. The autobrake is normally enabled during takeoff
and landing
procedures, when the aircraft's longitudinal deceleration system can be handled by the automated systems of the aircraft itself in order to keep the pilot
free to perform other tasks.
When the landing feature of the autobrake is engaged, the aircraft automatically engages pressurized wheel braking upon touchdown to the landing surface
. During the roll out, application of the brake pedals transfers control back to the pilot.
One of the main advantages of engaging the autobrake as opposed to manually pressing on brake pedals is the uniform deceleration mechanism of the autobrake. The aircraft automatically decelerates at the selected level regardless of other factors, such as aircraft drag
and other deceleration methods such as deployment of thrust reversers or spoilers
.
, the aircraft's autobrake can be set to the rejected takeoff
mode, commonly indicated on an aircraft instrument panel as RTO. In case of the Airbus A300-600 and A320 family models, "MAX" mode is set. In RTO setting, the aircraft monitors certain variables, depending on the autobrake model. Most autobrakes engage RTO braking if the pilot returns the throttle
to the "idle" position, or if reverse thrust is engaged. Other autobrake systems may monitor critical flight controls for failures.
Hydraulic brake
The hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically containing ethylene glycol, to transfer pressure from the controlling unit, which is usually near the operator of the vehicle, to the actual brake mechanism, which is usually at or near the wheel of the...
system for advanced airplanes. The autobrake is normally enabled during takeoff
Takeoff
Takeoff is the phase of flight in which an aerospace vehicle goes from the ground to flying in the air.For horizontal takeoff aircraft this usually involves starting with a transition from moving along the ground on a runway. For balloons, helicopters and some specialized fixed-wing aircraft , no...
and landing
Landing
thumb|A [[Mute Swan]] alighting. Note the ruffled feathers on top of the wings indicate that the swan is flying at the [[Stall |stall]]ing speed...
procedures, when the aircraft's longitudinal deceleration system can be handled by the automated systems of the aircraft itself in order to keep the pilot
Aviator
An aviator is a person who flies an aircraft. The first recorded use of the term was in 1887, as a variation of 'aviation', from the Latin avis , coined in 1863 by G. de la Landelle in Aviation Ou Navigation Aérienne...
free to perform other tasks.
Landing
While landing, the autobrake can aid in freeing up the pilot to allow him or her to monitor other systems (such as the execution of the landing flare). There are usually several settings for the "intensity," or hydraulic pressure of the brake mechanism. The selection of these settings are normally done on the aircraft instrument panel before landing. These are often numbered or labelled, with "1" or "LO" referring to braking for a light speed reduction, and subsequent numbers or designations up to "MAX" referring to more abrupt speed reductions.When the landing feature of the autobrake is engaged, the aircraft automatically engages pressurized wheel braking upon touchdown to the landing surface
Runway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
. During the roll out, application of the brake pedals transfers control back to the pilot.
One of the main advantages of engaging the autobrake as opposed to manually pressing on brake pedals is the uniform deceleration mechanism of the autobrake. The aircraft automatically decelerates at the selected level regardless of other factors, such as aircraft drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
and other deceleration methods such as deployment of thrust reversers or spoilers
Spoiler (aeronautics)
In aeronautics, a spoiler is a device intended to reduce lift in an aircraft. Spoilers are plates on the top surface of a wing which can be extended upward into the airflow and spoil it. By doing so, the spoiler creates a carefully controlled stall over the portion of the wing behind it, greatly...
.
Rejected takeoff
While taking offTakeoff
Takeoff is the phase of flight in which an aerospace vehicle goes from the ground to flying in the air.For horizontal takeoff aircraft this usually involves starting with a transition from moving along the ground on a runway. For balloons, helicopters and some specialized fixed-wing aircraft , no...
, the aircraft's autobrake can be set to the rejected takeoff
Rejected takeoff
A rejected takeoff or RTO is the situation in which it is decided to abort the takeoff of an airplane...
mode, commonly indicated on an aircraft instrument panel as RTO. In case of the Airbus A300-600 and A320 family models, "MAX" mode is set. In RTO setting, the aircraft monitors certain variables, depending on the autobrake model. Most autobrakes engage RTO braking if the pilot returns the throttle
Throttle
A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases , but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which...
to the "idle" position, or if reverse thrust is engaged. Other autobrake systems may monitor critical flight controls for failures.