GLS

Instrument Landing System

An Instrument Landing System (ILS) is a ground-based radio navigation system that provides pilots with lateral and vertical guidance when they can't see the runway. ILS systems are installed at the end of airport runways.

The basic components of an ILS are:

• Localizer antenna: Provides horizontal guidance
• Glide slope antenna: Provides vertical guidance (glide path)
• Outer Marker (OM): A basic component of an ILS
• Middle Marker (MM): Used for Category II instrument approach procedures
• Inner Marker (IM): Used for Category III instrument approach procedures