What is the purpose of the FAF in an ILS approach?

The purpose of the Final Approach Fix (FAF) in an Instrument Landing System (ILS) approach is to serve as the point at which the aircraft intercepts the glideslope. The FAF defines the transition between the initial approach segment and the final approach segment.

When an aircraft reaches the FAF, it should be at the proper altitude to begin descending along the designated glideslope towards the runway. This fix is crucial because it assures that the aircraft is on the correct path to safely land. The ILS guidance system provides precise lateral and vertical guidance, with the glideslope ensuring that the airplane remains on the intended descent angle towards the runway.

The other options, while they might relate to various aspects of flight operations and approach procedures, do not accurately capture the specific purpose of the FAF within the context of an ILS approach.