What effect does ALPHA LOCK have on the airplane?

ALPHA LOCK is a feature designed to enhance safety by preventing premature slat retraction when the aircraft is at high angles of attack or low speeds. This is critical during phases of flight, such as approach and landing, where maintaining lift is essential. By inhibiting slat retraction, ALPHA LOCK ensures that the aircraft maintains adequate stall margins and reduces the risk of uncommanded stall during these critical phases. This capability is particularly important for maintaining control and stability, as the slats play a significant role in increasing lift at lower speeds.

The other options do not accurately reflect the function of ALPHA LOCK. For instance, the automatic thrust increase to TO/GA is not a characteristic of this feature. Additionally, while certain modes may influence displays on the Primary Flight Display (PFD), ALPHA LOCK itself does not change the PFD presentation directly. Lastly, while pitch control is crucial in flight, ALPHA LOCK does not explicitly limit pitch to 30 degrees nose up; its primary function relates to slat retention at specific conditions to ensure safe operational limits.