Alpha floor protection:
This function enhances windshear survivability.
Alpha floor detection is available from lift off to a 100ft RA in approach.
When the alpha floor condition is activated, the FCPCs send a signal to the
FMGECs(Autothrust Function)which controls the TO/GA engine thrust, whatever the throttle control lever position.
The activation conditions are:
- Alpha filtered (3s) greater than a threshold depending on aircraft configuration, the GS variation and the difference between GS and airspeed.
or
- SS NU demand <-14° and theta >25°
or
- SS NU demand <-14°and alpha protection.
Alpha floor is inhibited when Mach is above 0.53
The Alpha floor can also be inhibited by the FMGEC under certain engine failure conditions with flaps extended.
(When a TLA is below 5° the system may consider the engine failed and therefore alpha floor may be inhibited)
Alpha Floor is displayed A.FLOOR on the FMA (in green and amber boxed) and at LH upper area of EWD.
Alpha lock function:
If alpha exceeds 8.5° or the speed goes below 148 kt, the slat retraction from position 1 to 0 is inhibited.
This inhibition is removed whenalpha goes below 8.2° and when the speed exceeds154 kt, in this case the slats automatically retract to 0.
Alpha lock activation isdisplayed as pulsing A LOCK instead of the regular S indication of the S/F positionindicator on the EWD.
Thealpha lock function is not active after the S/F lever has been set to 0.