At 148 kt, with flaps 0, what does Alpha Lock/Speed Lock do?

At 148 kt, with flaps 0, what does Alpha Lock/Speed Lock do?

• A. Alpha lock activates to inhibit slat retraction when AoA is high but ignores speed
• B. Alpha lock inhibits flap movement
• C. Alpha lock/speed lock activates and inhibits slat retraction if AoA > 8.5° or speed < 148 kt
• D. Alpha lock prevents any wing surface movement

Answer: (C)

Alpha Lock/Speed Lock is a protective logic for the wing devices that keeps the slats extended when lift needs to be preserved. It watches both angle of attack and speed, and it prevents slat retraction if either condition could compromise lift: AoA above about 8.5 degrees or speed below 148 knots. With flaps at zero, at a speed of 148 knots the system will inhibit slat retraction if the angle of attack is high enough, and otherwise it may allow retraction. So the correct description is that the lock activates and inhibits slat retraction when AoA > 8.5° or speed < 148 kt.

Alpha Lock/Speed Lock is a protective logic for the wing devices that keeps the slats extended when lift needs to be preserved. It watches both angle of attack and speed, and it prevents slat retraction if either condition could compromise lift: AoA above about 8.5 degrees or speed below 148 knots. With flaps at zero, at a speed of 148 knots the system will inhibit slat retraction if the angle of attack is high enough, and otherwise it may allow retraction. So the correct description is that the lock activates and inhibits slat retraction when AoA > 8.5° or speed < 148 kt.