Find why the FSX ILS localizer tracks beside the runway and fix wrong frequencies, NAV/GPS selection, offset approaches and scenery mismatches.
FSX’s ILS can guide you beside a runway when the approach is intentionally offset, the tuned localizer belongs to another runway end, add-on scenery and FSX navigation data disagree, or the autopilot is following GPS rather than NAV. First check the runway, frequency, front course, navigation source and CDI indication.
What does the localizer indication tell you?
The relationship between the localizer needle and the visible runway usually identifies the fault.
| What you see | Likely cause | What to check |
|---|---|---|
| Needle centred, but the runway remains consistently to one side | Offset localizer or scenery/navigation-data mismatch | Compare the published inbound course with the runway heading, then test without add-on airport scenery |
| Needle commands a turn away from the runway | Wrong runway-end localizer, back-course reception or incorrect front course | Runway number, ILS identifier, frequency and inbound course |
| Localizer needle moves, but the autopilot follows another line | GPS selected instead of NAV/VLOC, or the autopilot is using another receiver | NAV/GPS selector, GPS CDI mode and active NAV receiver |
| Aircraft crosses and recrosses the centreline | Excessive intercept angle or speed | Intercept the localizer at about 20–30 degrees while stabilised |
| Only the aircraft’s nose points to one side | Normal crosswind crab | Ground track and CDI position rather than nose direction |
How do I correct an off-centre FSX localizer?
The quickest way to correct the problem is to rebuild the ILS setup from the runway end backwards.
- Confirm the exact runway end. Runways 09 and 27 are not interchangeable. The reciprocal end may use another frequency, have a different approach, or have no ILS at all.
- Use the frequency stored in FSX. Check the simulator’s Map, Flight Planner or airport information. Stock FSX navigation data can differ from a modern real-world chart, while an add-on airport may provide its own frequency and course.
- Tune and identify NAV1. Put the frequency in the active side of
NAV1and listen for the correct Morse identifier. Most default FSX aircraft use NAV1 for autopilot localizer tracking unless their panel documentation says otherwise. - Select NAV or VLOC. Move the panel’s NAV/GPS selector to NAV, or set a Garmin-style GPS CDI source to VLOC. If GPS remains selected, the autopilot may follow the magenta flight-plan course while the localizer needle moves independently.
- Set the published front course. Rotate the course selector to the ILS inbound course, not merely the rounded runway number. This normally does not move the raw localizer beam, but it prevents misleading HSI presentation and problems with some autopilots or add-on avionics.
- Intercept from the front. Approach the localizer at a shallow angle and from the side appropriate to the published approach. Receiving it from behind or using the reciprocal runway can produce reverse or confusing guidance.
- Engage approach mode after a stable intercept. Capture the localizer before making large heading changes. A fast, steep intercept commonly causes overshoot, although it does not normally create a permanent parallel offset.
Our complete FSX ILS setup and capture sequence covers the full procedure, including NAV/GPS selection and front-course interception.
Can an ILS localizer be deliberately offset?
Some approaches are deliberately aligned at an angle to the runway rather than directly along its centreline.
Compare the published localizer course with the runway heading. A small difference can be magnetic rounding, but a clear angular difference accompanied by a stable, centred needle indicates an offset approach. Follow the localizer to the published visual transition point or minimums, then align visually as required; do not force the aircraft onto the runway centreline early and assume the receiver is wrong.
See our explanation of how to recognise and fly an offset localizer for the operational differences.
Why is the CDI centred when the runway is not?
A centred CDI over a visibly displaced runway usually means the radio facility and the scenery do not agree.
This often appears after installing replacement airport scenery. The package may move the runway to a more accurate position while FSX continues using a localizer from another airport facility file. Duplicate airport or AFCAD-style files can produce the same result when two packages define different runway and navaid positions.
- Disable the add-on airport temporarily. Restart FSX and fly the same approach using the stock airport.
- Check for overlapping airport packages. Keep only one active package that changes that airport unless its instructions explicitly require additional files.
- Retest the localizer. If alignment returns with the stock airport, the add-on’s runway and navaid data are mismatched. If the stock installation shows the same geometry, check whether FSX models the approach as offset.
No cockpit course adjustment can repair a beam that is geographically displaced from the scenery. The airport and localizer facility data must come from a matching scenery installation.
What if every FSX ILS has the same problem?
If every ILS guides the aircraft incorrectly, suspect the aircraft setup or controls rather than multiple airports.
Watch the raw localizer bar while the autopilot is engaged. If the bar moves towards the centre but the aircraft follows the GPS route, verify the navigation source and selected receiver; our guide to diagnosing an FSX autopilot that ignores GPS or NAV commands covers that fault. Add-on aircraft may also require their own avionics source or approach mode instead of the default FSX panel switch.
With the autopilot disconnected, persistent rolling or yawing can come from rudder trim, an uncentred axis or insufficient controller dead zone. Use these control-axis and trim checks for a simulator that pulls to one side before blaming the localizer.
Is the aircraft off-centre, or only pointing sideways?
In a crosswind, an aircraft may point to one side while tracking the localizer correctly.
If the CDI remains centred and the ground track runs along the runway centreline, the autopilot is simply holding a crab into wind. That is normal. The lateral-guidance problem is genuine only when the aircraft’s path—not just its nose—remains beside or diverges from the runway.