Learn what autopilot APR/APP mode controls, how it captures an ILS localiser and glideslope, why capture fails, and why it is not autoland.
In a flight simulator, autopilot approach (APR or APP) mode arms the autopilot to capture and track an approach’s lateral and vertical guidance—most commonly an ILS localiser and glideslope. It does not tune the approach, configure the aircraft, guarantee capture, or automatically land unless that aircraft has a correctly armed autoland system.
Across Microsoft Flight Simulator, FSX, X-Plane and Prepar3D, the exact behaviour depends more on the simulated aircraft and autopilot than on the simulator. Light-aircraft panels commonly label the button APR; airliners often use APP or APPR.
What happens when you press APR?
Pressing APR normally arms two capture modes: lateral guidance towards the final approach course and vertical guidance down the approach path.
On an ILS, those modes are the localiser and glideslope. With compatible GPS avionics, APR may instead capture GPS lateral guidance and a glidepath. The autopilot then commands bank and pitch to keep the corresponding deviation indicators centred.
| Mode | Lateral control | Vertical control |
|---|---|---|
| HDG | Follows the selected heading | Retains the separately selected vertical mode |
| NAV | Tracks the selected VOR, localiser or GPS source | Usually retains the existing vertical mode |
| APR/APP | Captures approach lateral guidance | Captures a glideslope or compatible glidepath |
| Autoland | Tracks the approach and runway centreline | Adds automatic flare and, where modelled, rollout |
APR normally arms before it captures. The flight mode annunciator may first show LOC and G/S as armed, then change their colour or position when each mode becomes active. Trust those annunciations rather than the button light. Our explanation of the main autopilot modes and engagement sequence covers the broader controls.
How do you use APR mode for an ILS approach?
Set up and intercept the published final approach before asking APR mode to capture it.
- Select the correct approach. Confirm the runway, ILS frequency, inbound course and minimum altitude from the procedure data available in the simulator.
- Choose the correct navigation source. Select LOC, VLOC or NAV rather than GPS unless the aircraft automatically switches sources. Tune the ILS manually where required.
- Intercept from a sensible position. Approach the localiser on a shallow intercept, commonly around 20–30 degrees, and remain below the glideslope. APR is not intended to rescue an aircraft arriving high, close and at a sharp angle.
- Arm APR or APP. Depending on the aircraft, this arms both LOC and G/S or follows a separately selected LOC mode.
- Confirm capture. Check that the localiser becomes active first and that G/S subsequently changes from armed to captured. Altitude hold remaining active while G/S is merely armed is normal.
- Manage the rest of the approach. APR does not normally control flaps, landing gear, speed or thrust. Continue configuring the aircraft and be ready to disconnect or go around.
The cockpit sequence varies between generations of simulator and avionics. We have separate procedures for setting up APR during an MSFS 2024 ILS and using APR, NAV/VLOC and glideslope capture in FSX.
Why does APR mode not capture the localiser or glideslope?
APR usually fails because the guidance is unavailable, the wrong source is selected, or the aircraft approaches outside the autopilot’s capture envelope.
- Wrong navigation source: the flight plan may be displayed on GPS while the autopilot needs LOC or VLOC for the tuned ILS.
- Incorrect frequency or runway: verify the ILS against the simulator’s procedure data. Add-on scenery and mismatched navigation data can occasionally disagree.
- Aircraft above the glideslope: most systems are designed to capture it from below. Descending through the beam from above may not capture and can produce an unstable approach.
- Intercept too steep or too close: use heading mode to establish a shallower intercept farther from the runway.
- No vertical guidance: a VOR, NDB, localiser-only or basic GPS approach does not necessarily provide a glideslope or glidepath for APR to follow.
- Mode overwritten: selecting HDG, NAV, vertical speed or another mode after arming APR may cancel part of the approach capture.
- Back-course approach: use the aircraft’s BC mode where supported. Do not expect normal APR mode to follow a usable glideslope on a localiser back course.
A mistake we see constantly is treating the magenta or green approach line as proof that APR has captured. It is only situational guidance until the mode annunciator confirms active LOC and G/S or their aircraft-specific equivalents.
Does APR mode work with GPS and RNAV approaches?
APR can follow an RNAV approach only when the simulated avionics support approach coupling and the loaded procedure supplies compatible lateral and vertical guidance.
An LPV or supported LNAV/VNAV procedure may show an armed and captured GP glidepath rather than an ILS G/S glideslope. An LNAV-only approach may have no approved vertical path; any advisory descent indication is not automatically equivalent to approach vertical guidance. For the associated loading, activation and minima decisions, see our procedure for flying an RNP approach in a simulator.
Is APR mode the same as autoland?
No—APR mode usually flies the approach but does not flare, touch down or keep the aircraft on the runway after landing.
Autoland requires a suitably equipped aircraft, a compatible approach, correct system configuration and an autopilot model that simulates flare and rollout. Some airliners also require multiple autopilot channels. Unless the flight mode annunciator explicitly confirms the required autoland status, plan to disconnect at the appropriate point and land manually.