Fix an FSX ILS glideslope that will not capture or track. Check NAV1, GPS/NAV, APR mode, intercept height, aircraft logic and airport scenery.
In FSX and FSX: Steam Edition, glideslope capture usually fails because NAV1 is mistuned, GPS remains selected, APR is not armed, or the aircraft reaches the beam from above. Tune the correct ILS, select NAV, intercept the localiser shallowly while level below the glideslope, then arm APR before the vertical needle centres.
What usually stops glideslope capture in FSX?
Most FSX ILS failures can be identified from what the needles and autopilot do during the intercept.
| What you see | Likely cause | What to check |
|---|---|---|
| Both ILS needles remain dead | Wrong frequency, frequency still in standby, out of reception range or no ILS on that runway | Verify the runway-end frequency using the navigation data installed in FSX and make it active on NAV1 |
| Needles are alive, but the aircraft follows the flight plan | GPS is still selected or the autopilot is using a different receiver | Move the GPS/NAV or CDI source selector to NAV and confirm the panel uses NAV1 |
| Localiser captures, but there is no glideslope indication | The approach is localiser-only, the glideslope component is missing, or scenery data are faulty | Confirm that the installed FSX airport provides a full ILS rather than only lateral guidance |
| Glideslope pointer crosses the centre, but the aircraft stays level | The aircraft is above the beam, APR/APP is not armed, or another vertical mode remains in command | Re-intercept from below and check the approach-mode indication |
| The aircraft captures and then oscillates or loses the path | Excessive speed, late configuration changes, turbulence, time acceleration or custom autopilot logic | Use normal simulation rate, stabilise earlier and follow the aircraft add-on’s mode sequence |
| Only one airport or runway fails | Outdated, duplicated or conflicting airport scenery | Test the same procedure at another default ILS runway |
If both needles are dead, start with the runway, active frequency and reception range. If the localiser works but the glideslope does not, concentrate on intercept height, APR mode and whether the runway really has vertical guidance in FSX.
How should I set up an FSX glideslope capture?
A reliable capture requires the correct radio source, a shallow localiser intercept and level flight below the glideslope.
- Confirm the correct runway end. ILS equipment is runway-specific. Do not assume the reciprocal runway has an ILS or uses the same frequency, and do not assume a modern real-world chart matches FSX’s older airport database.
- Tune and activate NAV1. Most stock FSX aircraft couple the autopilot to NAV1. Make sure the ILS frequency is active rather than sitting in the standby window. Add-on aircraft may use different receiver or flight-management logic.
- Check the station identification. An audible or displayed ILS identifier helps confirm that the receiver has the intended station. No identification may mean the frequency is wrong, the signal is out of range or the scenery does not provide that approach.
- Set the front course. Dial the inbound runway course on the course selector or OBS. The course setting does not tune the ILS, but it gives the correct display reference and affects tracking logic in some panels.
- Select NAV rather than GPS. On stock panels with a GPS/NAV switch, NAV tells the autopilot to follow the radio beam. A mistake we see repeatedly is tuning the ILS correctly while leaving the aircraft coupled to the GPS flight plan.
- Reduce speed and configure early. Establish a sensible approach speed and make the major flap, gear and power changes before capture. Poor configuration rarely prevents the receiver from detecting the beam, but it can stop the autopilot tracking it cleanly.
- Intercept the localiser shallowly. Use an intercept angle of about 30 degrees or less. Large cut-in angles encourage overshoots, especially in faster or heavier aircraft.
- Remain level below the glideslope. Use the procedure’s intercept altitude and allow the glideslope pointer to move towards the centre from above. If your chart and FSX disagree, use data appropriate to the airport scenery actually installed.
- Arm APR or APP before vertical capture. Stock FSX aircraft normally allow altitude hold to maintain the intercept altitude until the glideslope captures. NAV mode alone provides lateral tracking; it does not command a glideslope descent.
- Confirm actual coupling. Centred needles alone do not prove the autopilot has captured the ILS. Check the mode lights or flight-mode annunciator and watch for the aircraft to leave altitude hold and begin a controlled descent.
For the complete sequence from radio setup through localiser interception and descent, use our full FSX ILS setup and intercept procedure.
Why does the localiser capture but not the glideslope?
The localiser can capture without the glideslope because lateral and vertical guidance are separate parts of the approach.
You do not tune a separate glideslope frequency: the correct ILS localiser frequency automatically pairs the vertical signal. If the lateral needle works but there is no vertical indication, confirm that the runway has a full ILS in FSX. A localiser-only or back-course approach normally provides no usable glideslope.
If the vertical pointer is alive but the aircraft does not descend, check these causes:
- Intercepting from above: the most common cause. APR mode is designed to capture a descending beam from underneath, not dive down to retrieve it.
- NAV armed instead of APR/APP: NAV can track the localiser but does not add vertical coupling.
- APR armed too late: if the pointer has already passed through the capture point, extend the approach and set up another intercept.
- Wrong display or receiver: one receiver may be showing the ILS while the autopilot is coupled to another source.
- Custom add-on logic: complex aircraft may require LOC to capture first, followed by a separate APP command, or may use an avionics source independent of the stock GPS/NAV switch.
Do not force the descent with vertical-speed mode after a missed capture. That may cancel or override approach guidance, and it can create an unstable approach close to the ground.
Can FSX capture the glideslope from above?
Normal FSX ILS technique is to capture the glideslope from below; an above-path capture is unreliable and should not be planned.
When the aircraft is high, the glideslope pointer may pass through the centre while altitude hold remains engaged. Some custom aircraft may react differently, but that is not a sound way to test or fly the approach. Descending aggressively towards the beam can also produce a false or unstable capture.
If ATC vectors or late descent planning leave you above the path, maintain safe control, extend or re-vector the approach, and intercept again from below. Go around if a stable setup cannot be recovered.
Why does the aircraft capture the glideslope and then wander?
After capture, poor speed control, configuration changes and conflicting autopilot inputs are the usual reasons an aircraft cannot remain on the glideslope.
The glideslope mode normally controls pitch, not airspeed. Unless the aircraft has an active autothrottle system, you must adjust power to prevent acceleration or decay while the autopilot changes pitch. Extending gear or large flap increments after capture can also displace the aircraft from the beam.
- Return FSX to normal simulation rate; time acceleration can make autopilot corrections unstable.
- Avoid large power, trim or configuration changes after capture.
- Do not select vertical speed or altitude hold once the glideslope is coupled.
- Use the mode sequence specified for a complex add-on rather than assuming it behaves like a stock aircraft.
- Disconnect and go around if the aircraft begins severe pitch oscillations or cannot maintain a stable approach.
APR capture is not the same as autoland. Most stock FSX aircraft still require manual power management, flare and landing. A structured default 737 ILS practice scenario is useful for learning the capture indications without changing airports and procedures on every attempt.
How can I tell whether FSX scenery is causing the problem?
If every aircraft fails on one runway while the same aircraft works on other ILS approaches, the airport or scenery data are the likely cause.
FSX: Steam Edition retains the base simulator’s older airport and navigation data; it does not automatically make every runway match newer real-world charts. Runway renumbering, changed frequencies and later ILS installations can therefore create an apparent failure even when the simulator is behaving as designed.
Add-on airport files can introduce another problem. Duplicate AFCAD-style files, conflicting scenery layers or an airport designed for a different runway layout can place the localiser or glideslope incorrectly.
- One aircraft fails at several airports: suspect its panel, receiver selection or custom autopilot.
- Several aircraft fail on one runway: suspect the airport data or a scenery conflict.
- The default airport works after an add-on is disabled: the add-on or its scenery priority is responsible.
- The beam is visibly offset or has an implausible descent path: stop troubleshooting the autopilot and inspect the airport installation.
Test with a stock aircraft, calm weather and a known working default ILS. Then disable suspect airport scenery one area at a time and restart FSX before repeating exactly the same intercept. If a correction is needed, check our FSX scenery and airport add-ons, making sure any file matches the installed airport version and does not leave multiple competing airport definitions active.