Which device contributes to the aircraft's ability to fly at slower speeds?

Slats are devices located on the leading edge of an aircraft's wings and play a crucial role in enhancing the aircraft's aerodynamic performance during slower speeds, especially during takeoff and landing phases. When deployed, slats increase the curvature of the wing (camber), which helps maintain smooth airflow over the wings at lower airspeeds. This alteration allows the wings to generate sufficient lift even when the aircraft is flying at slower speeds, which is essential for preventing stalling.

In contrast, heading indicators are navigational instruments that show the aircraft's heading relative to magnetic north and do not affect aerodynamic performance. A GPU (Ground Power Unit) is used to provide power to the aircraft while on the ground, which has no impact on the flight characteristics. Similarly, an APU (Auxiliary Power Unit) mainly supplies power and pneumatic pressure while the aircraft is on the ground, serving functions unrelated to flight performance. Therefore, slats are the component most directly responsible for enabling slower flight speeds safely.