What is the function of the Instrument Landing System (ILS)?

The Instrument Landing System (ILS) plays a critical role in guiding aircraft during the approach and landing phases of flight, specifically under low visibility conditions. The system consists of a series of ground-based radio beacons that provide precise lateral and vertical guidance to pilots, allowing them to align the aircraft with the runway effectively. This guidance is essential for ensuring a safe landing, especially when visual cues are limited, such as in fog, rain, or at night.

While the other options suggest functions related to takeoff, vehicle taxiing, or emergency procedures, they do not capture the primary purpose of the ILS. The ILS is not designed to assist with takeoffs, as aircraft typically rely on visual references and other instruments for that phase of flight. Additionally, the system is not intended to facilitate vehicle taxiing, which involves different ground navigation technologies and procedures. Finally, while having an ILS can be beneficial during emergency situations, its main function is not as an emergency landing procedure but rather as a landing aid under various visibility conditions.