Learn why an aircraft drifts off course during autoland, how crosswinds, ILS setup and simulator scenery cause it, and when to go around.
In real-world aviation, an aircraft can drift off course during an ILS autoland because the autopilot follows the received localiser signal, not the painted runway centreline. Crosswind, an unstable intercept, incorrect setup, signal disturbance or mismatched simulator scenery can cause an offset. A crabbed nose alone is normal; sustained localiser deviation is not.
Is a crabbed aircraft actually drifting off course?
No—a crab angle in crosswind does not by itself mean the aircraft is drifting away from the runway.
The aircraft's heading may point into wind while its ground track remains on the localiser. Check the localiser deviation and the movement of the aircraft relative to the centreline, rather than judging alignment from the nose alone. Some autoland systems apply a type-specific de-crab or alignment command during the flare.
The localiser provides lateral guidance, while the glideslope controls the vertical path. Our explanation of how localiser and glideslope guidance work together covers the distinction and why glideslope capture cannot correct a lateral tracking problem.
What causes genuine autoland drift?
True lateral drift usually comes from an incorrect or disturbed localiser signal, inadequate control authority, an unstable capture or a system that is not configured for a complete autoland.
| What you observe | Likely explanation | What to check |
|---|---|---|
| Nose points into wind but localiser stays centred | Normal crosswind crab | Ground track and localiser deviation |
| Localiser oscillates before the flare | Poor intercept, gusts, excessive speed or late capture | Intercept angle, stabilisation, speed and wind limits |
| Localiser is centred but the runway looks offset | Offset facility or simulator scenery and navigation-data mismatch | Runway suitability, scenery placement and selected approach |
| Autoland status disappears or downgrades | Missing autopilot channel, sensor fault or invalid configuration | Flight-mode annunciations and aircraft procedure |
| Aircraft leaves the centreline after touchdown | Rollout guidance is absent, disengaged or overridden | Rollout mode, rudder input, controller noise and runway condition |
An ILS beam can also be distorted by terrain, reflections, snow or aircraft and vehicles near the localiser antenna. CAT II/III operations protect critical areas around the equipment, but a practice autoland conducted without those protections may encounter signal movement even when an ordinary manual ILS approach remains usable.
Autoland capability is aircraft- and runway-specific. A single autopilot may fly a coupled ILS without providing the redundancy, flare logic or rollout control required for an approved automatic landing. Our guide to autoland modes, redundancy and runway requirements explains that distinction.
When should pilots abandon an autoland?
Pilots should abandon the autoland when the localiser becomes unstable, a required landing status is lost, an ILS warning appears or the aircraft exceeds the applicable stabilised-approach and autoland limits.
The exact response depends on the aircraft, failure status, height and operator procedure. A manual landing may be permitted if the runway is visible and the aircraft is stable; otherwise the correct response is a go-around. The crew must monitor raw ILS deviation and flight-mode annunciations throughout—the word APP or an armed mode does not prove that the localiser has captured correctly.
How do I fix autoland drift in a flight simulator?
Start by separating an approach-setup error from an aircraft, weather or airport-scenery problem.
- Confirm that the runway supports the landing. Select a usable ILS and an aircraft model that simulates autoland. An RNAV, visual or localiser-only approach does not become an autoland merely because the approach mode is armed.
- Verify the ILS data. Check the frequency, front course, identifier and navigation source. Ensure the FMS approach matches the active runway rather than its reciprocal or a similarly named procedure.
- Use a stable intercept. Approach the localiser from a shallow angle, at a sensible speed and from below the glideslope. A late capture can produce overshoots that become more obvious as the localiser grows more sensitive near the runway.
- Read the flight-mode annunciator. Confirm that both localiser and glideslope are captured, not merely armed, and that the required landing status appears for that aircraft.
- Configure the required autopilot channels. Follow the aircraft's sequence for engaging additional channels. Pressing a second autopilot button cannot repair an incorrect frequency, bad intercept or misplaced ILS beam.
- Repeat the approach in calm weather. Remove strong wind and turbulence, clear simulated failures and check for a noisy rudder or yaw axis. If the fault disappears, wind limits, control inputs or the aircraft's flight model are the likely cause.
- Isolate the aircraft from the airport. Fly the same aircraft to another suitable ILS, then test another autoland-capable aircraft on the original runway. This shows whether the fault follows the aircraft or the scenery.
- Check scenery and navigation-data conflicts. A consistently centred localiser that guides the aircraft beside the painted runway strongly suggests displaced scenery, an outdated runway position or duplicate airport packages.
Mode logic differs between aircraft. For type-specific checks, use our A320 ILS capture and autoland procedure or the 737 dual-channel approach and rollout procedure.