Why does autopilot stop working in FSX?

In FSX and FSX: Steam Edition, autopilot most often stops when its master switch is toggled, a mapped command or add-on protection disconnects it, electrical or avionics power is lost, or a lateral or vertical mode cannot capture. First check whether the AP master disengaged or merely stopped following the commanded mode.

Is the autopilot disengaging or just missing a mode?

An extinguished AP master light indicates a real disconnect; an illuminated master with the aircraft ignoring its route usually indicates a mode, navigation-source or capture problem. This distinction prevents a great deal of unnecessary controller resetting and aircraft reinstallation.

How do I stop FSX autopilot disconnecting?

Check control assignments first, then aircraft power and flight condition before changing navigation settings.

1. Stabilise the aircraft. Return to normal airspeed and attitude, use normal simulation speed, disengage the autopilot and trim for roughly hands-off flight. Advanced add-ons may disconnect for excessive bank, pitch, overspeed, stall warning or strong manual control input.
2. Inspect the AP master command. The default Z key toggles the FSX autopilot master. Look for a stuck key or a joystick button assigned to the same command. Our reference for FSX keyboard and autopilot commands helps identify accidental or remapped inputs.
3. Remove duplicate assignments. A hardware button configured through both FSX and separate controller software can issue the command twice, making the autopilot engage and immediately disengage. Also check for assignments to autopilot disconnect and pitch trim.
4. Check the control axes. Centre the yoke or stick and watch for jumping elevator, aileron or trim input. In many default aircraft, axis movement fights the autopilot rather than cleanly disconnecting it; custom aircraft may treat it as manual takeover. Disconnect the controller temporarily to prove the cause. If its inputs are erratic or missing, follow our FSX controller and axis troubleshooting steps.
5. Confirm electrical power. Turn on the required battery, generator or alternator and avionics switches for that aircraft. Battery power alone may operate the panel initially, then allow the autopilot and radios to fail as the battery runs down.
6. Test simple modes. Set the heading bug to the present heading, engage the master and select HDG. Once level, test ALT according to that panel’s operating logic. If these work, the autopilot itself is functioning and the fault lies in the route, radio or approach setup.
7. Disable deliberate failures. Check for any scheduled failures configured in the saved flight or aircraft. Do not assume reloading the same saved situation clears them.

Why is autopilot on but not following the route or altitude?

The AP master only enables the system; the appropriate heading, navigation, approach or vertical mode must also be selected and captured.

• Heading: Select HDG and place the heading bug where you want the aircraft to turn. NAV or APR may cancel or override heading mode, depending on the panel.
• GPS route: In aircraft using the default FSX navigation logic, select GPS as the navigation source, activate a valid flight-plan leg and use NAV mode. The aircraft must approach the desired track at a sensible intercept angle. Work through our FSX GPS and NAV capture checks if NAV remains armed or follows the wrong course.
• VOR navigation: Select NAV rather than GPS, tune the correct NAV receiver, set the course and intercept a signal within reception range.
• Altitude: Turning an altitude selector does not command a climb in every FSX aircraft. Some panels capture the altitude held when ALT is pressed; others use a preselected altitude together with vertical speed or another pitch mode. Follow the logic shown by that aircraft’s panel rather than assuming every default and add-on aircraft behaves alike.

A mode shown as armed is waiting for capture. It has not yet taken control. Reaching the selected altitude and changing automatically from vertical-speed mode to altitude hold is normal, not an autopilot failure.

Why does FSX autopilot stop after a few minutes?

An autopilot that works initially and then dies alongside the radios or glass displays usually indicates that the aircraft has been running on battery power without an operating generator or alternator.

If the rest of the panel remains powered, watch for a repeating controller command, trim axis or add-on protection instead. High simulation rates can also make older FSX autopilots and complex add-on systems unstable; reproduce the flight at normal speed before treating the behaviour as a fault.

Why does it fail only on an ILS approach?

An autopilot that works en route but fails on final normally has an ILS setup or capture problem rather than a failed autopilot.

NAV1 must be tuned to the correct localiser, the navigation source must be set appropriately, APR must be armed, and the aircraft should intercept the localiser before meeting the glideslope from below. For the complete setup and recovery sequence, use our ILS localiser and glideslope capture checklist.

How can I tell whether an add-on aircraft is causing it?

Test the same controls in a fresh flight using a default FSX aircraft equipped with a conventional autopilot.

• If the default aircraft works, investigate the add-on’s custom power, flight-director, protection and panel-state logic.
• If every aircraft disconnects, concentrate on FSX control assignments, controller software and electrical procedures.
• If the fault appears only in one saved flight, create a new flight rather than repeatedly reloading the same aircraft state.

Reinstalling FSX should be the last step. A clean default-aircraft test usually identifies whether the problem belongs to the simulator, the hardware configuration or one particular aircraft without disturbing a working installation.