Localizer

Localizer is the horizontal guidance component of an ILS, providing the pilot with left/right alignment relative to the runway extended centerline. The localizer antenna is located at the far end of the runway.

The localizer operates on VHF frequencies (108.10-111.95 MHz, odd tenths). It provides a signal accurate to approximately ±0.5 degrees from the centerline. A localizer-only approach (LOC approach) uses only lateral guidance without glideslope, resulting in higher minimums than a full ILS approach.

The back course provides guidance for approaches from the opposite direction, but with reversed sensing (left-right indications are mirrored).