Fix FSX autopilot when it won’t follow GPS or NAV: choose the source, activate the route leg, capture the course and stop unwanted turns.
In FSX and FSX: Steam Edition, the autopilot follows a GPS route only when the GPS has an active leg, the panel’s navigation source is set to GPS, and NAV mode captures that course. To track a VOR, select NAV, tune active NAV1, set the OBS course, and intercept within reception range.
Which settings make FSX follow GPS or NAV guidance?
The navigation source and autopilot mode must both match the guidance you want to track. They are separate controls: the NAV/GPS selector chooses the signal, while the autopilot’s NAV mode commands the aircraft to follow that signal.
A mistake we see constantly is selecting NAV as the source because the pilot intends to use NAV mode. To follow the magenta GPS flight-plan line, select GPS as the source and then engage or arm NAV on the autopilot.
| Guidance to follow | Source | Required setup | Autopilot mode |
|---|---|---|---|
| GPS flight plan | GPS | Active GPS leg with a valid waypoint ahead | NAV |
| VOR radial or airway | NAV | VOR in active NAV1, correct OBS course and usable reception | NAV |
| ILS localizer and glideslope | NAV | Localizer in active NAV1 and inbound course selected | APR |
NAV tracking is lateral guidance. The word “NAV” on the autopilot does not necessarily mean the NAV radio is its source; with GPS selected, the same NAV mode tracks the GPS course instead.
This logic applies to stock FSX aircraft and conventional panels. An add-on with its own FMC, FMGC, LNAV or custom autopilot may bypass the generic NAV/GPS switch entirely.
How do I make the autopilot capture a GPS route?
Approach an active GPS leg in heading mode, select GPS as the source, and arm NAV while the course deviation is moving towards the centre.
- Load and activate the flight plan. Confirm that the route appears inside the aircraft’s GPS, not only on the map or in the Flight Planner. Our guide to loading a route and coupling the FSX GPS to the autopilot covers the complete stock-gauge procedure.
- Check the active leg. The GPS should identify a next waypoint and show an active course to it. A visible route without an active leg gives the autopilot nothing useful to track.
- Correct a waypoint behind you. Activate an appropriate leg ahead or use Direct-To for the waypoint you actually want. Direct-To changes the immediate guidance, so check how the route will sequence afterwards.
- Select GPS as the navigation source. Look for NAV/GPS, GPS/NAV, CDI or source controls on the main panel, HSI, navigation display or a pop-up panel. Pressing NAV on the autopilot does not change this source by itself.
- Establish a sensible intercept. Use HDG mode to approach the course rather than flying parallel to it or away from it. An intercept of roughly 20°–45° is suitable for most conventional FSX autopilots.
- Engage the autopilot correctly. Switch on the avionics and autopilot master, trim the aircraft, then use HDG while establishing the intercept. A flight director alone displays commands but does not fly the aircraft.
- Arm NAV and verify capture. Watch the CDI and mode indication. On panels that distinguish armed from active modes, NAV may remain armed until the deviation closes; it should then replace HDG and track the course.
Do not judge GPS tracking solely by where the nose points. In a crosswind, the aircraft may crab away from the desired track while remaining correctly centred on it.
NAV is armed but does not work: why won’t it capture?
NAV normally remains armed because the selected source has no valid guidance or the aircraft is not approaching that guidance from a capturable direction.
- Wrong source: NAV is selected while trying to follow GPS, or GPS is selected while trying to track a VOR or localizer.
- No active GPS leg: The route is displayed, but the intended segment is not active. Confirm the next waypoint and desired track on the GPS.
- Poor intercept: The aircraft is parallel to the course, moving away from it or crossing at an excessive angle. Turn towards the course in HDG mode and arm NAV again.
- GPS OBS or suspended sequencing: OBS mode can prevent normal waypoint sequencing. Return to normal leg sequencing unless you deliberately need a fixed course to a waypoint.
- Frequency in the wrong place: Most stock panels use active NAV1 for VOR and ILS tracking. A frequency in standby or NAV2 will not feed that autopilot.
- Station out of range: VOR reception depends on the station, aircraft altitude and distance. A tuned frequency alone does not guarantee usable guidance.
- Incorrect OBS course: Set the course you intend to intercept and check the TO/FROM indication. The autopilot cannot determine which radial you meant.
- Competing mode or command: A repeated controller assignment may re-engage HDG, switch NAV off or disconnect the autopilot.
- Aircraft-specific logic: If the route works in a stock aircraft but not the add-on, the add-on probably expects its own FMC or lateral mode.
For radio navigation, our NAV1 tuning and VOR-tracking instructions explain active versus standby frequencies, OBS selection and TO/FROM indications.
It won’t follow and is still turning — what should I check?
A continuing turn usually means the autopilot is obeying the wrong course, heading or waypoint rather than failing to respond.
- It turns back towards the route: The active waypoint or leg is behind the aircraft. Select a leg or waypoint ahead.
- It keeps turning towards the heading bug: HDG is still active and NAV has not captured. Set an intercept heading and watch for NAV to become active.
- It overshoots and reverses repeatedly: Reduce the intercept angle, stabilise the aircraft and return to normal simulation rate if acceleration is making the autopilot unstable.
- It turns away immediately after NAV selection: Recheck the GPS/NAV source, CDI indication, OBS course and TO/FROM flag.
- It banks even after autopilot disconnection: Check controller axes, stuck keys and duplicate assignments. This is no longer a navigation-source problem.
If modes drop out, the autopilot disconnects or the aircraft ignores commands beyond NAV tracking, use our broader FSX autopilot power and control-conflict checklist.
What if the NAV/GPS selector or none of those options are present?
If your reaction is “no, it isn’t there”, the aircraft may hide the source control, use different terminology or rely on a custom navigation system.
Check the virtual cockpit and the aircraft’s 2D pop-up instrument panels. The control may be labelled CDI, source, NAV/GPS or GPS/NAV, and it may sit beside the HSI rather than the autopilot.
A keyboard or controller command for NAV hold only selects the autopilot mode; it does not provide a missing GPS source selector. If the installed panel has no compatible source control, the stock autopilot may be unable to couple to GPS. You can still steer along the route with HDG mode, but automatic GPS tracking requires a panel or aircraft navigation system designed to supply that guidance.
Why does NAV tracking work differently in an A340?
FSX does not include a stock Airbus A340, so every A340 in the simulator is an add-on and its autopilot behaviour depends on that package.
A detailed A340 may require the route to be entered and activated in its MCDU/FMGC, followed by the aircraft’s managed lateral or NAV mode. In that case, generic FSX instructions about a NAV/GPS switch may not apply. A simpler A340 may reuse conventional FSX gauges and behave like the donor panel instead.
Identify which panel and navigation system the add-on uses before troubleshooting. The aircraft model’s exterior appearance does not tell you whether it uses stock NAV hold, a borrowed panel or a custom Airbus-style system.
Why does GPS tracking stop when I select an ILS?
GPS tracking stops because an ILS requires the lateral source to change from the GPS flight-plan course to the NAV1 localizer signal.
Before intercepting, tune the localizer into active NAV1, set the published inbound course, select NAV as the source and arm APR from a reasonable intercept angle. If the aircraft will not capture that radio beam, follow our localizer capture troubleshooting procedure.
Capture the glideslope from below unless the aircraft’s own documentation specifies otherwise. An ordinary GPS route does not provide the stock FSX autopilot with automatic vertical approach guidance.
Does GPS or NAV mode control altitude and speed?
No. On the stock FSX autopilot, GPS and NAV modes provide lateral course guidance only.
Altitude hold, vertical speed, pitch and engine power are controlled separately. Autothrottle works only in aircraft equipped with it, and the generic autopilot will not descend automatically at ordinary flight-plan waypoints. Custom aircraft may add VNAV or managed vertical modes, but those belong to the add-on’s own systems rather than standard FSX NAV tracking.