What is the function of the EMER FLAP switch?

The function of the EMER FLAP switch is to extend slats to a predefined angle, which is crucial during certain phases of flight, particularly during takeoff and landing. This switch activates the slats in a manner that maintains aerodynamic performance and ensures that the aircraft achieves optimal lift at lower speeds.

When the EMER FLAP switch is engaged, it provides a reliable and rapid deployment of the slats, which play an essential role in enhancing the airfoil's characteristics by delaying airflow separation. This action helps improve lift and enhances stall resistance, which is critical during low-speed operations.

In an emergency, having the ability to quickly extend slats to a predefined angle ensures that pilots can react swiftly to maintain control of the aircraft, particularly when unexpected situations arise during approach or takeoff. The focus on slats distinguishes this function clearly from options that relate to flaps or retraction of wing devices, as the primary objective is to enhance lift characteristics rather than to modify overall wing configuration or inhibit movements based on speed.