ILS
Instrument Landing System
Last updated: April 20, 2026 · Maintained by Aviatr Editorial Team
What is ILS?
An ILS (Instrument Landing System) is a precision approach navigation aid providing both lateral guidance via the localizer and vertical guidance via the glideslope, allowing aircraft to descend safely to minimums as low as 200 feet AGL in Category I operations. ILS is the standard precision approach system at major European airports in low-visibility conditions.
How is ILS used?
ILS is the gold-standard precision approach: London Heathrow, Frankfurt, Paris CDG, and Amsterdam Schiphol operate ILS on every runway. The pilot tunes the ILS frequency, identifies the localizer by Morse code, then tracks the glideslope and localizer simultaneously on the course deviation indicator during descent. Category II and III ILS enable autoland capability to near-zero decision heights, but require certified avionics, crew training, and runway visual range minima that vary by category. Modern RNAV-based LPV approaches substitute for ILS at airports without the ground infrastructure, but the procedural profile and pilot workload are comparable. Every commercial pilot logs hundreds of ILS approaches during type-rating training. CPL and ATPL skill tests include ILS approaches under partial-panel and simulated low-visibility conditions as standard items.