descent path guidance element of an ILS

The equipment in an ILS that provides vertical (up/down) guidance to a landing aircraft.

The ideal descent path to a runway. It can be electronically defined by radio signals transmitted from the ground. An aircraft carrying a special radio receiver can detect this electronic glidepath and follow it down to the runway.

A device used for instrument approaches.

Vertical/altitude guidance element of an ILS

A navigation aid used on ILS landing approaches, consisting of a horizontal needle that displays the correct vertical position for the aircraft in its approach to the runway threshold. The pilot keeps the needle centered by continuously monitoring the angle of descent and adjusting it as required. The glideslope is used in conjunction with the Localizer.