What are the advantages/disadvantages of an autobrake system? In particular I am interested in the Fokker 100 system.

Have any studies been done for the F100 autobrakes and the affects that this system has on the landing gears?


2 Answers 2


Autobrake is a smart system which basically implies that the pressure is applied to the brakes when a set of circumstances are reached, such as when the plane detects that it is on the ground and the thrust is in idle.

There are in principle only advantages with an autobrake system, since it reduces pilot workload during the moments after landings and reduces necessary runway to stop. While autobrake has what I know not been the reason for any accidents, the faulty computer logic of the computers in the autobrake and spoiler system contributed to a Lufthansa accident in 1993.

As I gather, the Fokker 100 autobrake will be activated when the thrust levers are commanded to idle reverse and the system is on. It has 5 settings: RTO (Rejected Takeoff), OFF and LO/MID/HI, the latter 3 representing the amount of automatic brake pressure.

Autobrake is closely related to the spoilers, which are simply a button on the Fokker 70/100. The direct effect of spoilers on the landing gear is that they are pushed harder down onto the runway (since the lift from the wings is disrupted), making the braking more effective early on during landing.

Source (not very good but the best i could find)


I don't know for certain about the Fokker, but most autobrake systems are designed to produce a specific rate of retardation, using the equivilent of ABS and antiskid, which greatly increases passenger comfort. The effect of opening and closing spoliers, flaps and reverse thrust are all compenstaed for automatically so the pilot does not need to worry about adjusting braking force to maintain smoothness at a time of maximum stress.

The disadvantages are that it is a system and can fail which is why every landing check list includes "Verify Autobrake Operation".

Less obvious advantages include reduced wear on braking systems, reduced tyre wear, automatic compensation for single wheel lockups etc.


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