Learn to use the Bendix/King KAP 140 autopilot in a flight simulator: engage modes, capture altitude, fly approaches and fix common faults.
To use the Bendix/King KAP 140 in a flight simulator, trim the aircraft, set the heading bug, navigation source, course and target altitude, then engage AP and select HDG, NAV, APR or ALT as required. Confirm each armed and captured mode on the display, and control power and airspeed yourself.
In Microsoft Flight Simulator, X-Plane, FSX and Prepar3D, the exact controls depend on the aircraft and how thoroughly its developer modelled the unit. Treat the KAP 140's annunciations as the authority: pressing a mode button does not mean that mode has captured. Our guide to autopilot modes, sensors and active guidance explains that distinction in more detail.
Which KAP 140 version is fitted?
The KAP 140 exists in several configurations, so first establish which functions the simulated aircraft actually has.
| Configuration | What it controls | Pilot responsibility |
|---|---|---|
| Single-axis | Roll, heading and lateral navigation | Control pitch, vertical speed, trim and altitude manually |
| Two-axis | Roll and pitch, including vertical speed and altitude hold | Set power, monitor airspeed and initiate altitude changes |
| Two-axis with altitude preselect | Roll, pitch and capture of an armed selected altitude | Select and arm the altitude, choose a safe climb or descent rate, and manage power |
A missing pitch or altitude function is not necessarily a simulator fault; the aircraft may have a simpler installation. Aircraft packages also differ in fidelity. Our look at a KAP 140-equipped Comanche add-on provides a practical example of a two-axis installation.
How do you set up and engage the KAP 140?
Set the references before engaging the autopilot, then verify every active mode rather than assuming the aeroplane will follow the flight plan automatically.
- Power the unit. Turn on the aircraft's required electrical and avionics systems and check the autopilot circuit breaker or switch. Allow the self-test to finish; some simulations display
PFTduring this process. - Set the lateral guidance. Move the heading bug to the desired heading. For NAV or APR, select the correct GPS or VLOC source, set the inbound course where required, and ensure the intended GPS leg or radio aid is active.
- Set the vertical references. If altitude preselect is fitted, dial the target altitude. Synchronise any separate KAP 140 barometric setting with the main altimeter.
- Stabilise and trim manually. Establish a sensible airspeed, power setting and attitude. Engaging while badly out of trim often produces a sharp pitch change or immediate trim warning.
- Engage the autopilot. Press AP and verify that the AP annunciation appears. Many two-axis installations initially enter basic ROL and VS modes; they do not automatically select heading or altitude hold.
- Select the required mode. Use HDG to follow the bug, NAV to intercept navigation guidance, APR for an approach or ALT to hold altitude. Watch for an armed indication changing to a captured or active indication.
- Keep flying the engine. The KAP 140 does not operate the throttle, mixture, propeller, flaps or landing gear. Adjust power and configuration while monitoring airspeed.
What do the KAP 140 mode annunciations mean?
The annunciator tells you what the autopilot is controlling now and what it is waiting to capture.
| Indication | Meaning |
|---|---|
| ROL | Basic wings-level or roll-attitude mode; it does not follow the heading bug. |
| HDG | Turns to and maintains the heading selected by the heading bug. |
| NAV ARM | Navigation guidance is selected, but the capture conditions have not yet been met. |
| NAV | Tracks the active VOR, localiser or GPS lateral guidance, depending on the selected source. |
| APR ARM | Approach capture is armed. |
| APR | Approach lateral guidance has captured. |
| REV or BC | Tracks a localiser back course with corrected lateral sensing; glideslope guidance is not used. |
| VS | Maintains the commanded vertical speed. UP and DN alter that command on suitably equipped units. |
| ALT ARM | A selected altitude is armed for capture. |
| ALT | Altitude hold is active. |
| GS ARM or GS | Glideslope or compatible vertical approach guidance is armed or captured. |
Labels and display behaviour vary between KAP 140 configurations and simulator add-ons. The aircraft-specific manual takes precedence over generic simulator key assignments.
How do I capture a selected altitude?
A preselect-equipped KAP 140 captures an altitude only after that target has been selected and armed.
- Select the target altitude using the KAP 140's own controls rather than relying on the simulator's toolbar altitude setting.
- Establish the climb or descent with suitable power and a safe vertical-speed command.
- Arm altitude capture using the installation's altitude-arm control and confirm that
ALT ARMorARMappears. - Monitor the capture. The unit should reduce vertical speed near the selected altitude and change to ALT hold.
- Reset power for level flight and confirm that airspeed remains appropriate.
On a version without altitude preselect, level the aircraft manually at the required altitude and then press ALT to hold it. Do not confuse ALT hold with altitude capture: pressing ALT during a climb may simply hold the altitude at which the button was pressed.
The KAP 140 has no reliable airspeed protection. If commanded to maintain an excessive climb rate, it may continue pitching up as the aircraft slows. Reduce vertical speed or add power before airspeed approaches the stall region.
Can the KAP 140 fly an ILS or GPS approach?
A suitably equipped two-axis KAP 140 can track an ILS localiser and glideslope, but GPS lateral and vertical coupling depends on the aircraft's avionics installation and simulator modelling.
- Prepare the approach. Tune and select VLOC for an ILS, or activate the correct GPS approach and leg for GPS guidance.
- Intercept sensibly. Use HDG mode to approach the final course at a moderate angle. For an ILS, remain below the glideslope before capture.
- Press APR. Confirm APR ARM rather than assuming capture occurred immediately.
- Verify capture. Check that lateral APR becomes active and, where supported, GS changes from armed to captured.
- Manage the descent. Set power, extend flaps and gear as required, and watch speed. The KAP 140 does not provide autothrottle, flare or automatic landing.
Use REV only for a published localiser back-course procedure, not a normal front-course ILS. Some simulated installations can couple GPS-derived vertical guidance; others provide lateral navigation only. For planning the rest of the flight around these modes, see our complete simulated IFR workflow.
Why is the KAP 140 not following the selected mode?
Most KAP 140 problems come from an incorrect navigation source, an armed mode that has not captured, poor trim or conflicting simulator control assignments.
| Symptom | Likely cause and fix |
|---|---|
| AP will not engage | Complete the self-test, check avionics power and the autopilot breaker, clear simulated failures, and make sure an assigned disconnect button is not stuck or duplicated. |
| HDG ignores the bug | Confirm HDG is active, move the correct heading bug and align a drifting directional gyro. If an external GPSS mode is fitted, disable it when you want ordinary heading-bug control. |
| NAV or APR remains armed | Select the correct GPS/VLOC source, activate a valid course or flight-plan leg, and intercept closer to the course at a shallower angle. |
| Aircraft turns the wrong way | Check the OBS course, active navigation source and whether REV/back-course mode was selected accidentally. |
| Glideslope does not capture | Verify that the installation has pitch control, the approach supplies vertical guidance, APR is armed, and the aircraft is intercepting from below. |
| Altitude oscillates or overshoots | Disconnect, stabilise and trim the aircraft, then re-engage. Return the simulator to normal time speed and remove conflicting pitch, trim or generic autopilot assignments. |
| Autopilot disconnects unexpectedly | Look for noisy control axes, trim commands, electrical interruptions, excessive attitude or add-on-specific protection logic. Our diagnosis of repeated autopilot disconnections covers those faults in depth. |
How should I disconnect the KAP 140?
Use the assigned autopilot-disconnect control, hold the flight controls, verify that the AP annunciation disappears, and retrim before manoeuvring.
A correctly modelled installation may sound an aural warning and may disconnect when the pilot operates electric trim. Do not fight the servos or make a large manual control input while AP is still displayed. Confirm the aircraft's attitude and trim immediately after every disconnect, especially during an approach.