Which of the following are supplementary components of an ILS?

The correct answer identifies the supplementary components of an Instrument Landing System (ILS) as approach lights, a compass locator, and Distance Measuring Equipment (DME).

Approach lights are visual aids that enhance the pilot's ability to see the runway during approach, particularly in low visibility conditions. They provide a transition from instrument flight to visual flight, thereby improving safety during landing.

A compass locator is a low-power, non-directional beacon used to identify the location of the ILS approach. It aids in approach navigation by providing additional situational awareness to the pilot.

DME is crucial for determining the distance between the aircraft and the runway threshold, contributing to precise guidance during the landing phase. It works in conjunction with the ILS to ensure that pilots can manage their descent profile accurately.

These components work together as part of the ILS to ensure a safe and reliable approach to landing, particularly in challenging weather conditions.