Plain English Meaning

The equipment on the ground that sends out the signals an aircraft uses to fly an ILS approach. It includes the transmitters that tell the airplane whether it is left or right of the runway centerline, whether it is above or below the correct descent path, and how far it is from the runway.

Full Definition

The ground-based equipment that makes up an Instrument Landing System (ILS), consisting of the localizer transmitter (lateral guidance to the runway centerline), the glide slope transmitter (vertical guidance along the proper descent angle), and the marker beacons or used to along the . Together these transmitters produce the signals that the aircraft's ILS interprets to fly a .