FCOM:
Alpha-floor protection automatically sets the thrust at TOGA thrust, when the aircraft reaches a very high angle of attack.
The Flight Augmentation Computer (FAC) generates the signal that triggers the alpha-floor mode. This, in turn, sets TOGA thrust on the engines, regardless of the thrust lever positions (Refer to DSC-22_30-90 A/THR Modes - General).
The FAC sends this signal when:
‐ The angle of attack is above a predetermined threshold, that is a function of the configuration.