What does the localizer provide during an ILS approach?

The localizer provides horizontal guidance during an Instrument Landing System (ILS) approach. It helps pilots align the aircraft with the runway centerline. The localizer's signal is transmitted from an antenna located at the end of the runway, allowing the aircraft's navigation system to interpret the position relative to the runway's centerline.

This horizontal guidance is crucial for precise lateral navigation, ensuring that the aircraft approaches the runway from the correct angle, which is essential for a safe landing. It does not provide altitude or vertical guidance; that's the role of the glideslope, which works in tandem with the localizer in an ILS setup to guide the aircraft down a proper descent path. Additionally, aspects like landing speeds are determined by the aircraft's own systems and pilot's inputs rather than the localizer itself.