Fix X-Plane ILS localizer and glideslope problems by checking NAV source, frequency, approach type, intercept geometry, failures and nav data.
ILS localizer and glideslope signals in X-Plane usually do not work because the wrong runway frequency is active, the CDI remains in GPS mode, or the aircraft is approaching from the back-course side or above the glidepath. A localizer-only procedure, X-Plane’s downwind-ILS suppression, equipment failures or mismatched navigation data can be responsible too.
How do I fix an ILS that is not working in X-Plane?
The reliable fix is to verify the published facility first, then the receiver, navigation source, approach geometry and X-Plane settings. These checks apply to X-Plane 11 and 12, although cockpit labels vary between aircraft.
- Confirm that the approach is a full ILS. Check the runway direction, localizer frequency, front course and approach type. A procedure labelled LOC, LOC/DME or back course may not provide a glideslope. If your chart and simulator disagree, follow our method for checking the runway, ILS frequency, course and chart-cycle data.
- Put the frequency in the active NAV receiver. The localizer frequency must be active, not left in the standby window or entered as a COM frequency. Use NAV1 for the first test because some aircraft display or autopilot installations use NAV1 for ILS guidance. There is no separate glideslope frequency to tune; the receiver selects its paired glideslope channel automatically.
- Change the CDI source from GPS to VLOC, LOC or NAV1. A loaded or activated GPS approach does not guarantee that the radio source has changed. On Garmin displays, green indications normally mean radio navigation while magenta indicates GPS guidance. For the default Garmin installation, use these G1000 source-selection and ILS capture checks.
- Set the published front course. The course knob does not tune the localizer, and a basic CDI can still sense it with the wrong course selected. However, the correct course is needed for an intelligible HSI presentation and reliable flight-director or autopilot behaviour.
- Intercept from the correct side and below the glidepath. Approach the front-course side, become established on or close to the localizer, and intercept the glideslope from below at the published altitude. A 20–30-degree localizer intercept provides a clean test setup. Our explanation of how localizer and glideslope coverage behaves covers the signal geometry in more detail.
- Check X-Plane’s downwind ILS option. When
Disable downwind ILSesis enabled, X-Plane can suppress an approach serving a runway with a tailwind. Test with wind favouring the selected runway or temporarily turn that option off. This catches many cases where the same ILS works after changing runway direction. - Arm APP or APR mode for autopilot capture. NAV mode usually captures lateral guidance only; APP or APR arms both localizer and glideslope capture. The localizer normally captures first, followed by the glideslope. Autopilot mode cannot create a missing radio signal, so confirm that the raw deviation indicators are alive before blaming the autopilot.
- Check power and simulated failures. Verify the avionics master, relevant electrical buses, radio and display are powered. Reset any NAV receiver, glideslope, antenna or instrument failures in X-Plane’s failure controls; the exact component labels depend on the aircraft. Hearing the station’s Morse identifier supports successful reception, although silence can simply mean the NAV audio or volume is off.
What does each ILS symptom mean?
The combination of indications usually identifies which part of the setup has failed.
| Symptom | Most likely causes | Check next |
|---|---|---|
| No localizer or glideslope | Wrong or standby frequency, GPS source selected, no electrical power, downwind ILS disabled or receiver failure | Active NAV1 frequency, VLOC source, avionics power and X-Plane settings |
| Localizer works, no glideslope | Localizer-only procedure, back-course approach, glideslope failure or unsupported aircraft equipment | Approach title, front-course direction and glideslope receiver |
| Both pointers appear, but autopilot does not capture | APP mode not armed, intercept too steep, aircraft above the glidepath or autopilot using another receiver | Annunciations, capture source, intercept angle and altitude |
| Needles guide away from the runway | Wrong runway end, back-course operation, intentionally offset localizer or scenery/navigation-data mismatch | Published course, approach type and nav-data cycle |
Why does the localizer work but not the glideslope?
A working localizer with no glideslope usually means the procedure is not a full ILS, the aircraft is receiving the back course, or the glideslope equipment has failed. Check the difference between a full ILS and a localizer-only approach before changing cockpit settings.
On a full ILS, tuning the localizer automatically tunes the paired glideslope channel. Do not try to enter a separate UHF glideslope frequency. A back-course approach does not provide a valid glideslope, even if the localizer needle is moving.
If the glideslope diamond is visible but the autopilot will not capture it, the signal is working. The usual problem is that the aircraft is above the glidepath, APP mode is not armed, or the autopilot is listening to a different NAV receiver. Being above the path does not necessarily remove the indication, but many autopilots will not capture a glideslope from above.
Does APP mode make the ILS signal appear?
No; APP or APR mode commands the autopilot to capture signals that the NAV receiver is already receiving. It does not tune the radio, change the CDI from GPS to VLOC or activate an ILS transmitter.
Some glass cockpits and add-on aircraft hide the ILS scales until a radio-navigation or LS display mode is selected. That is a display configuration issue rather than missing reception. Likewise, loading an ILS into the FMS may supply flight-plan sequencing without tuning the localizer unless that aircraft explicitly supports automatic tuning.
Why is the ILS missing or offset at only one airport?
An airport-specific problem usually points to stale navigation data, incompatible custom scenery or an intentionally offset approach rather than a general receiver fault. Check the published procedure first because not every localizer is aligned with the runway centreline.
- Test the same approach from the same position with a default X-Plane aircraft. If it works, inspect the add-on aircraft’s radio, avionics or navigation database.
- Test a known full ILS at another airport. Successful reception there isolates the fault to the first airport or its data.
- Temporarily disable the custom airport and reload X-Plane. A displaced custom runway can disagree with the simulator’s localizer coordinates.
- Make sure X-Plane, the aircraft and the chart source refer to a compatible navigation-data cycle. Runway renumbering and partial database updates commonly create frequency, course or alignment discrepancies.
If the localizer and glideslope work in a default aircraft with stock scenery, X-Plane’s radio simulation is functioning. The remaining fault lies in the add-on aircraft, custom airport or its separate navigation data.