Learn why an ILS localizer is offset from the runway, which course to set, how to align visually and when the apparent offset is a sim data fault.
An ILS localizer is offset when terrain, obstacles, airport geometry or antenna-siting limits prevent the beam from being aligned with the runway centreline. Fly the published localizer course and altitudes, not a line aimed at the runway; once the required visual references are clear, transition to the centreline as charted or execute the missed approach.
In our Aviation & Real-World Flying coverage, the crucial distinction is between a genuinely offset procedure and a small apparent heading discrepancy. The approach chart, rather than the runway number or outside view, identifies which one you have.
What causes an ILS localizer to be offset?
A true offset localizer provides a usable, obstacle-protected approach path where a conventional centreline installation is impractical. Common causes include rising terrain, buildings, restricted land beyond the runway, signal-reflection problems and the need to guide aircraft around an obstacle before the final visual segment.
The antenna array itself may sit away from the extended centreline while its transmitted course remains aligned with the runway, so antenna position alone does not prove that an approach is offset. Depending on the aviation authority and procedure design, non-aligned guidance may be identified as an offset ILS, LOC, LDA or IGS. The charted title, notes and minima determine what it legally provides; our guide to distinguishing localizer-only guidance from a complete ILS explains why the label matters.
| What you see | Likely explanation | Correct action |
|---|---|---|
| Localizer course differs slightly from the runway number | Often normal runway-number rounding, magnetic variation or chart/database differences | Set and fly the published front course |
| Chart depicts the final course crossing the runway centreline at an angle | A designed offset approach | Track the beam until the charted visual transition or missed-approach point |
| Chart shows an aligned ILS but the simulator beam misses the runway | Possible scenery, navigation-data or magnetic-model mismatch | Verify the data before treating it as a real offset |
Use the approach chart to confirm the localizer course, vertical guidance, minima, visual manoeuvre and missed approach. We cover the necessary checks in our guide to verifying ILS frequencies, courses and chart data.
How do you fly an offset localizer approach?
Fly the instrument segment exactly as published, then make the visual alignment only when the required references are visible and a normal, stable landing remains possible.
- Brief the complete procedure. Identify whether it provides a glideslope, where the offset course leads, the applicable DA or MDA, any prescribed visual turn and the missed-approach instructions.
- Tune and identify the facility. Select the published frequency and front course. Confirm the identifier where the aircraft or simulator models it; receiving a needle is not enough to prove that the correct localizer is selected.
- Intercept the published course. Use a shallow intercept and avoid joining from above any published glideslope. For detailed capture technique, see our practical method for intercepting and tracking a localizer.
- Follow the authorised vertical profile. If the chart provides a glideslope and DA, use them. A localizer-only or LDA procedure normally uses step-down fixes, an MDA and a missed-approach point. Do not follow an uncharted glideslope indication merely because a diamond appears.
- Keep the localizer centred. Do not steer towards the runway early because it looks displaced through the windscreen. Leaving the protected course prematurely can point the aircraft towards terrain or obstacles.
- Transition visually as charted. Once the required visual references are available, follow any prescribed manoeuvre and align smoothly with the runway. If visual contact is lost, the turn cannot be completed safely or the aircraft will not meet your stabilised-approach criteria, execute the published missed approach.
Should I set the runway heading or localizer course?
Set the published localizer front course, even when it differs from the runway heading. The runway number is only a rounded representation of magnetic direction, while the charted course describes the actual approach guidance.
On many receivers, turning the course selector does not rotate or relocate the localizer beam. Even so, the correct course setting matters because the HSI presentation, flight director, autopilot logic or back-course interpretation may use it. Changing the selector to the runway heading will not repair a genuinely offset beam.
Can the autopilot land from an offset localizer?
An autopilot may capture and track an offset localizer, but it will normally continue following that beam rather than turn itself onto the runway centreline. At the visual transition, the pilot may need to disconnect the autopilot or select an appropriate lateral mode and fly the alignment manually, according to the aircraft procedure.
Do not assume that an offset approach supports autoland. Autoland requires specific approval for the aircraft, installation, procedure and runway; treat the landing as manual unless the governing documentation explicitly authorises otherwise.
Why does the localizer look offset only in the simulator?
An apparent offset in a flight simulator is often caused by navigation data and airport scenery representing different revisions. A repositioned or renumbered runway may be visually modelled in one place while the localizer remains at older coordinates.
- Confirm that the frequency and procedure belong to the correct runway and approach variant.
- Compare the published localizer course with the exact runway magnetic heading, not just its rounded runway number.
- Check for duplicate or conflicting airport scenery and its priority within the simulator.
- Ensure the aircraft navigation database and airport scenery describe compatible runway geometry.
- Test with the default airport if an add-on airport produces the discrepancy.
If the chart depicts a centreline-aligned approach but a correctly tuned localizer consistently guides every aircraft beside the runway, treat that as a simulator data or scenery fault—not as permission to abandon the beam and improvise an offset approach.