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Upskill / Avionics and Flight Deck Systems / Instrument landing system (ILS)

Instrument landing system (ILS)

How the localizer and glide path guide aircraft to the runway, how the system is installed, flown, inspected and maintained, and how satellite approaches are changing its future.

By Aerospace Garage Desk · Basics · 40 minutes · 20 narrated pages · Updated October 2026

  1. Part 1 · Basics

    Instrument landing system (ILS)You are here

  2. Part 2 · In practice

    Flight management system (FMS)

  3. Part 3 · Managing it

    Coming soon

  4. Part 4 · What's next

    Coming soon

Navigation and guidance · See the Flight Path →

What you will be able to do

  • ✓ Explain how the localizer and glide path create guidance with 90/150 Hz tones and DDM, and how frequencies, identification, markers and DME complete the system
  • ✓ Describe how ILS ground equipment is sited and protected, including critical and sensitive areas, safeguarding and interference
  • ✓ Describe airborne receivers and displays, and state the CAT I, II and III minima and the approvals each needs
  • ✓ Explain autoland, flight inspection, monitoring and maintenance of ILS ground equipment
  • ✓ Compare ILS with GBAS (GLS) and SBAS (LPV) approaches and explain where ILS is heading

Course content

Session 1 · How an ILS works

1

  1. A path to a runway you cannot see · free preview
  2. Two tones and a difference
  3. Frequencies, identity, markers and DME
  4. Worked example: height and distance on a 3° glide path
Session 2 · Ground installation, critical and sensitive areas

2

  1. Siting the localizer and the glide path
  2. Critical and sensitive areas
  3. What else can bend the beam
  4. Worked example: protecting the critical areas on a murky morning
Session 3 · On board: receivers, displays and approach categories

3

  1. From antenna to receiver
  2. Reading the guidance
  3. Category I, II and III
  4. From the investigation file: a false glide path at Eindhoven
Session 4 · Autoland, flight inspection and maintenance

4

  1. Autoland
  2. Checking the signal from the air
  3. Monitors and maintenance
  4. Worked example: judging a localizer flight inspection
Session 5 · GBAS, SBAS and the future of ILS

5

  1. GLS: an ILS look-alike built on satellites
  2. SBAS and LPV approaches
  3. Interference, resilience and the future of ILS
  4. Worked example: fog at the destination: ILS, GLS or LPV?

Who this course is for

  • Navaid technicians who maintain and monitor localizer and glide path equipment
  • Aerodrome safeguarding staff protecting ILS critical and sensitive areas
  • Pilots and operations staff working with CAT II and CAT III approvals and autoland

You need: Basic radio or flying knowledge; Performance-based navigation (PBN) helps for the final session.

Upskill courses are for professional development and are not approved by any aviation authority. Learner Terms

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