What is the main function of ground proximity warning systems (GPWS)?

The main function of ground proximity warning systems (GPWS) is to warn pilots of impending terrain conflicts. GPWS is designed to increase situational awareness for pilots and enhance safety by providing alerts when an aircraft is in danger of flying too close to the ground or colliding with terrain. It uses various sensors to detect the altitude of the aircraft and compares this to the terrain below, issuing warnings when the aircraft is approaching a potentially hazardous situation, such as during descent or landing.

This capability is critical for preventing controlled flight into terrain (CFIT) incidents, which occur when an airworthy aircraft, under the control of a pilot, unintentionally flies into the ground or water. The system provides vital alerts that allow for timely corrective actions, thus playing a crucial role in enhancing flight safety.

The other choices do not accurately represent the GPWS's primary purpose. While communication with ground control is essential for flight operations, it falls outside the GPWS's function. Similarly, alerting pilots of potential mid-air collisions pertains to traffic collision avoidance systems (TCAS), and directing aircraft to the nearest airport is not a function of GPWS but rather part of flight management and navigation systems.