Topic summary
Localizer

Extracted from the Wikipedia article Instrument landing system localizer.
Carrier frequency pairings
Localizer (LOC) and glide path (G/P) (a.k.a. glide slope [G/S]) carrier frequencies are paired so that the navigation radio automatically tunes the G/S frequency which corresponds to the selected LOC frequency. The LOC signal is in the 110 MHz range while the G/S signal is in the 330 MHz range.