What is AUTOSLAT?

AUTOSLAT ensures that when the flaps are set to 1, 2, or 5 degrees and the wing approaches a high angle of attack nearing a stall condition, the flaps and slats automatically deploy to their fully extended positions. When the flaps are extended up to 5 degrees, the Leading Edge Devices (LE)—namely the leading-edge flaps and slats—are in a partially extended position. Since these leading-edge flaps and slats play a critical role in generating lift at low speeds and maintaining controllability at high angles of attack, their full extension is essential to recover from a stall.

The AUTOSLAT operation is normally powered by the Hydraulic System B. If Hydraulic System B is not operational, the system can still function through the PTU (Power Transfer Unit), which is powered by Hydraulic System A.

Leading Edge Devices (LE) are crucial during takeoff and landing. Therefore, when the flaps are extended during these phases, we verify their deployment by saying “Flap 1, GREEN LIGHT”, confirming the extension of the LEs via the green light. (It’s also useful to cross-check the green lights on the AFT Overhead Panel.)