Term

ILS

Daniel MarkFounder & Editor, Aviatopia
Published Mar 1, 2026Updated Mar 1, 20261 min read

Instrument Landing System — a precision radio-based approach system providing lateral (localizer) and vertical (glideslope) guidance for landing in low visibility.

aviation-glossary

Quick Facts

Type
Navigation System
Also Known As
ILS
Used By
Pilots, ATC

Definition#

ILS stands for Instrument Landing System. It is a precision approach system that provides lateral guidance (localizer) and vertical guidance (glideslope) to align an aircraft with the runway centerline and correct descent path.

Why It Matters Operationally#

ILS enables landings in reduced visibility conditions (CAT I through CAT III). CAT III ILS with autoland capability allows landings with RVR as low as 300 ft (CAT IIIb) or zero visibility (CAT IIIc).

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