In case of people set thrust levers to idle and forget to set one thrust reverser in IDLE for exemple
My FCOM says DSC 27-10-20 SPEED BRAKES AND GROUND SPOILERS
GROUND SPOILER CONTROL
Spoilers 1 to 5 act as ground spoilers.
When a ground spoiler surface on one wing fails, the symmetric ground spoiler surface on the other wing is inhibited.
ARMING
The pilot arms the ground spoilers by pulling the speedbrake control lever up into the armed position.
FULL EXTENSION – REJECTED TAKEOFF PHASE
▪ If the ground spoilers are armed and the speed exceeds 72 kt, the ground spoilers will automatically extend as soon as both thrust levers are reset to idle.
▪ If the ground spoilers are not armed and the speed exceeds 72 kt, the ground spoilers will automatically extend as soon as reverse is selected on one engine (the other thrust lever remains at idle).
DSC 32-30-10 AUTOBRAKE -GENERAL
SYSTEM ACTIVATION
Automatic braking is activated:
‐ at the command for ground spoilers extension (Refer to DSC-27-10-20 Speed Brakes and Ground Spoilers - Speed Brake Control), for LO and MED mode.
‐ at the command for ground spoilers extension and the aircraft speed is above 40 kt, for MAX mode.
Therefore, if the aircraft makes an acceleration stop and begins to decelerate when its speed is under 72 kt, the automatic braking will not activate because the ground spoilers will not extend.
For autobrake to activate, at least two SEC's must be operative.
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