Learn the FSX Cessna 172 autopilot controls for heading, altitude, VOR, GPS and ILS tracking, plus fixes when KAP 140 modes will not capture.
To use the autopilot in the default FSX Cessna 172SP, turn on electrical and avionics power, stabilise and trim, press AP, then select HDG, NAV or APR for lateral guidance. Press ALT to hold present altitude, or use UP/DN for climb or descent. Throttle, mixture, flaps and landing remain manual.
Which autopilot does the FSX Cessna 172 use?
The stock Cessna 172SP in FSX and FSX: Steam Edition uses a simulated Bendix/King KAP 140 two-axis autopilot. Add-on Cessnas may replace it with a different unit, so the following controls apply specifically to the default aircraft.
| Control | What it does | Key detail |
|---|---|---|
| AP | Engages or disconnects the autopilot | AP alone does not necessarily select heading or altitude hold. |
| HDG | Follows the heading bug | Move the bug on the heading indicator before selecting the mode. |
| NAV | Tracks NAV1 or the GPS route | The panel's NAV/GPS selector determines which source it follows. |
| APR | Captures an approach course | Used for an ILS localiser and glideslope rather than ordinary route tracking. |
| REV | Tracks a published localiser back course | Do not use it for a normal front-course ILS. |
| ALT | Holds the present altitude | It does not command a climb to a newly chosen altitude. |
| UP/DN | Changes commanded vertical speed | Watch airspeed because the autopilot does not control power. |
How do I engage the Cessna 172 autopilot?
Stabilise the aircraft before engagement, then select each required mode and confirm its annunciation on the autopilot display. Poor trim is the usual cause of an abrupt pitch change, so establish the attitude and power first; our guide to Cessna 172 trimming and stabilised flight covers that groundwork.
- Prepare the aircraft. Turn on the battery, alternator and avionics, establish a safe airspeed, then trim until little control pressure is required.
- Set the heading bug. Move the bug on the heading indicator to the direction you want to fly.
- Engage AP. Press AP and check that the unit has engaged. Do not assume AP alone has selected HDG, NAV or ALT.
- Select lateral guidance. Press HDG for the heading bug, or use NAV or APR after configuring the appropriate radio or GPS source.
- Choose the vertical mode. Press ALT while level to hold that altitude. To climb or descend, use UP/DN to command a modest vertical speed, adjust power, and press ALT upon reaching the required altitude.
- Monitor the aircraft. Check airspeed, altitude, heading and mode annunciations. Disconnect with the AP button or FSX's default
Zautopilot-master command before making large manual corrections.
A common mistake is commanding an aggressive climb while leaving cruise power unchanged. The autopilot raises the nose to satisfy vertical speed, allowing the Cessna to slow towards a stall. Use a conservative climb rate and manage power just as you would when hand-flying.
How do I make the FSX Cessna 172 follow a GPS route?
Load and activate the route in the GPS, set the cockpit NAV/GPS selector to GPS, intercept the magenta course in HDG mode, then press NAV. NAV mode may remain armed until the aircraft reaches a suitable intercept position.
- Activate the correct GPS leg. A displayed flight plan is not enough if the wrong leg is active; see our explanation of loading and activating a Cessna GPS route.
- Select GPS as the source. The NAV/GPS switch must show GPS. Leaving it on NAV tells the autopilot to follow NAV1 instead.
- Intercept with HDG mode. Use the heading bug to approach the magenta line at a moderate angle rather than expecting NAV mode to recover from any position.
- Press NAV and verify capture. Check that NAV changes from armed to active and that the CDI begins centring.
For VOR navigation, use the opposite source setting: select NAV, tune and identify NAV1, set the OBS course, establish an intercept and press NAV. NAV2 cannot drive the default autopilot. If the aeroplane still ignores the CDI, work through our FSX GPS and NAV capture checks.
Can the Cessna 172 autopilot fly an ILS or land?
The default Cessna 172 autopilot can capture an ILS localiser and glideslope, but it cannot perform an automatic landing. Tune the ILS on NAV1, select NAV rather than GPS as the source, set the published front course and intercept the localiser from below the glideslope at a sensible angle.
Engage AP and press APR before capture. Once established, manage throttle, speed and flaps yourself, monitor both needles and disconnect the autopilot with enough height to stabilise for the flare. APR is not an autothrottle or autoland mode.
A GPS approach uses different source selection and may provide lateral guidance without an ILS-style glideslope. Our FSX GPS approach procedure explains that workflow without confusing it with an ILS.
Why will the C172 autopilot not hold course or altitude?
Most FSX C172 autopilot failures come from the wrong source, an uncaptured mode, poor trim or an unrealistic vertical-speed command. Check the illuminated mode rather than relying only on the AP master indication.
- NAV does not turn towards the route: verify the NAV/GPS selector, active GPS leg or NAV1 frequency, then establish an intercept in HDG mode.
- NAV remains armed: the aircraft may be too far from the course or approaching it at an unsuitable angle.
- ALT maintains the wrong height: ALT captures the altitude at which it is pressed. Use UP/DN to climb or descend, then press ALT at the required level.
- The aircraft loses speed while climbing: reduce the commanded vertical speed and add power. The KAP 140 has no speed or throttle control.
- The aircraft pitches or oscillates: disengage, stabilise and retrim. Strong turbulence, high simulation rates and conflicting controller inputs can also upset FSX's autopilot.
- AP disconnects unexpectedly: check electrical and avionics power, then look for a controller button or keyboard assignment repeatedly sending the autopilot-master command.