An ILS approach is a radio-guided instrument approach that lines you up with the runway centreline and descent path. In a flight simulator, it works much like the real thing: you tune the ILS, identify the runway, intercept the localiser laterally, capture the glideslope vertically, then follow both indications to decision height or the runway.
What does ILS mean?
ILS stands for Instrument Landing System. It is designed to help us fly an accurate approach to a runway when visibility is poor, cloud is low, or we simply want a stable instrument approach.
The system gives us two main pieces of guidance:
- Localiser for left-right alignment with the runway centreline.
- Glideslope for up-down guidance on the correct descent angle, usually around 3 degrees.
In most simulators, these signals are shown on a CDI, HSI, PFD, or similar instrument display. If the aircraft has a suitable autopilot, we can often couple the approach and let the autopilot track it.
How does an ILS approach work?
The ILS uses ground transmitters near the runway. One transmitter sends the localiser signal along the extended runway centreline. Another sends the glideslope signal upward along the proper descent path.
Our aircraft receiver compares the signal strength on each side of those beams. If we drift left or right of centreline, or above or below the descent path, the instrument needle or flight director shows the correction needed. Centre the needles and we are on the approach.
| ILS part | What it does | What we see in the sim |
|---|---|---|
| Localiser | Guides us left and right to the runway centreline | CDI/HSI needle moves left or right |
| Glideslope | Guides us down on the correct descent angle | Vertical needle or glide path indicator moves up or down |
| DME or fixes | Helps us judge distance and step-down points | Distance readout, GPS fixes, or approach waypoints |
| Marker beacons or alerts | Traditional position cues on some approaches | Tones/lights in some aircraft and simulators, absent in others |
What do we actually do in the simulator?
In practical sim flying, an ILS is not just “press APP and wait”. We need to be on the correct frequency, on the correct course, at the correct altitude, and in a sensible position to intercept the approach.
If any of those are wrong, the aeroplane may ignore the glideslope, overshoot the localiser, or descend badly. That is why ILS flying feels simple when it is set up properly and frustrating when it is not.
How to fly an ILS approach in a flight simulator
- Find the approach data. We need the runway's ILS frequency, inbound course, final approach fixes, and any altitude restrictions. Not every runway has an ILS, and some have only a localiser without a glideslope.
- Tune and identify the ILS. Set the correct NAV frequency in the aircraft's radio and, if your panel supports it, confirm the Morse identifier. This helps avoid following the wrong beacon if several are nearby.
- Set the inbound course. Put the published runway or front-course heading on the course selector or HSI. In many aircraft this improves situational awareness and autopilot tracking, even if the receiver technically works without it.
- Get established for the intercept. Join vectors, a transition, or the published approach so you intercept the localiser at a shallow angle. Around 20 to 30 degrees works well in most sims.
- Be below the glideslope. This is a major one. We should normally capture the glideslope from below, not from above. If we are high, many autopilots will never capture it properly.
- Arm approach mode. If using autopilot, select the mode that captures localiser and glideslope, often labelled APP or APR. If hand-flying, use the needles or flight director to track the signals.
- Capture the localiser. As the lateral needle centres, turn to maintain runway centreline. Make small corrections. Chasing the needle with large bank inputs usually leads to weaving.
- Capture the glideslope. When the vertical indicator starts moving down towards centre from above the display, begin descent or let the autopilot capture it. Configure the aircraft early so you are not rushing.
- Fly a stable final. Manage speed, flaps, gear, power, and trim so the aircraft stays on both needles. Cross-check altitude and distance against the approach profile rather than trusting a single instrument blindly.
- Continue to minima or go around. At decision altitude or minimums, either continue visually if you have the required runway references, or execute a missed approach. In the sim, practising the go-around is just as useful as the approach itself.
What instruments show the ILS?
That depends on the aircraft and simulator. Older analogue cockpits may use a CDI needle and separate glideslope indicator. Glass cockpits usually show localiser and glideslope on the PFD, often with magenta or green guidance bars and annunciations for armed or captured modes.
In airliners and more complex aircraft, we may also see:
- Flight director command bars
- Autopilot mode annunciations
- Radio altitude readouts
- Decision height callouts
- Raw-data needles alongside FMS guidance
Even in a modern cockpit, we still need to understand the raw ILS indications. GPS magenta lines are helpful, but the ILS itself is a radio signal, not a satellite approach.
Can the autopilot fly the ILS for us?
Often yes, but only if the aircraft is equipped for it and we set it up correctly. In many sims, the autopilot can capture the localiser and glideslope and fly down final very accurately. In some aircraft, it can even continue into an autoland-style rollout if that capability is modelled.
But we should not assume every sim aircraft does this properly. Some default aircraft simplify the system. Some add-on aircraft model it in much more detail. And some older or lighter aircraft may have approach mode but no autoland logic at all.
The key point is that approach mode does not fix bad setup. If we arm it while too high, too fast, too close, or on the wrong frequency, it may do nothing useful.
Why will the localiser or glideslope not capture?
This is the most common ILS problem in a flight simulator. Usually the issue is not the beacon. It is the setup.
- Wrong frequency: easy to do, especially at airports with several nearby navaids.
- Wrong runway: the loaded approach in the GPS may not match the tuned ILS.
- Too high: glideslope should normally be intercepted from below.
- Bad intercept angle: crossing the localiser too sharply can cause overshoots.
- Incorrect course set: not always fatal, but it can confuse situational awareness and some systems.
- Back course confusion: approaching from the opposite end can give misleading indications unless the aircraft supports the proper mode.
- GPS/NAV source mismatch: many glass cockpits need the navigation source switched from GPS/FMS to NAV/LOC.
- Localiser-only approach: some runways have no glideslope at all.
If the aeroplane will not descend on the beam, check altitude first. In sim training, being above the glideslope is the classic mistake.
What is the difference between an ILS and other approaches?
Not every instrument approach works the same way. An ILS is a precision approach because it provides both lateral and vertical guidance. Other approaches may provide one or the other, or use satellites rather than ground radio beacons.
| Approach type | Lateral guidance | Vertical guidance | Typical use in sims |
|---|---|---|---|
| ILS | Yes | Yes | Classic runway approach using radio signals |
| Localiser | Yes | No | Runway alignment without glideslope |
| VOR/NDB | Yes | No | Older non-precision approaches |
| RNAV/GPS | Yes | Sometimes | Satellite-based approaches in many modern aircraft |
If we want the easiest route to a stable instrument landing in most simulators, an ILS is usually the best place to start.
Do all flight simulators model ILS the same way?
No. The basic concept is the same, but the fidelity varies. Some simulators model radio propagation, terrain masking, localiser sensitivity and autopilot behaviour in detail. Others are more forgiving or simplified.
Aircraft also matter. A simple trainer with old NAV radios behaves differently from a modern glass-cockpit turboprop or a heavy jet. The same ILS frequency can feel easy in one aircraft and busy in another because workload, stability and avionics logic differ.
That is why we always recommend learning the underlying method rather than memorising one panel layout. Once we understand localiser, glideslope, intercept geometry and configuration, the skills transfer well.
Best practice for a smooth ILS in the sim
- Brief the approach before starting down.
- Slow down and configure early rather than on the glidepath.
- Intercept the localiser with a modest angle.
- Capture the glideslope from below.
- Use small heading and power changes.
- Cross-check altitude against distance or fixes.
- Be ready to go around if the approach becomes unstable.
If you want more aircraft, panels and training-friendly downloads for simulator flying, our library is at https://flyawaysimulation.com/downloads/.
So, what is an ILS approach in simple terms?
It is the runway's radio guide. In a flight simulator, we tune it, intercept it, and follow two signals: one keeps us lined up with the centreline, the other keeps us on the right descent path. Do that cleanly, and the aircraft arrives over the threshold stable, accurate and ready to land.