In the FCTM for the A320 family of aircraft's under the SOP Takeoff chapter it is mentioned that the alpha lock function can intervene when performing a takeoff at heavy weights.

Can someone please explain the logic behind this ?


Alpha Lock is a protection that will prevent surfaces retraction after take off if the angle of attack (ALPHA)is high for the next retracted position of the flaps/slats lever. So even if the pilot puts the selector in the retraction direction the order will be postponed till the angle of attack decreases. This is managed by the Fly By Wire logics. The logics takes into account more particularly the angle of attack and the configuration speed limits.

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  • $\begingroup$ On A320, it can only happen between FLAPS 1 and FLAPS 0 conf. And only if AOA Is over 8.5deg or speed below 148kts. $\endgroup$ – Chris Lau Jul 25 '19 at 12:54

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