Autopilot (AFCS)

The E3X reproduces the real unit’s automatic flight control system (AFCS). The E3X itself computes the mode logic, the annunciations, and the flight director. It then couples them to whatever autopilot your aircraft actually has.

The AFCS window

Touch the AFCS status box at the top of the PFD, or open Main Menu → Flight Controls, for the Automatic Flight Control System window. The button grid matches the real unit’s controller:

• AP · FD · YD · ESP · LVL
• HDG · TRK · NAV · APPR
• IAS · ALT · VS · VNAV
• A context pair below. In pitch and VS modes it is Nose Up / Nose Down. In IAS mode it is Slower / Faster. In altitude hold it is Higher Alt / Lower Alt. Each press is one real-unit increment (0.5°, 100 fpm, 1 kt, 10 ft; the altitude adjustment has a ±200 ft limit).

Keys that cannot do anything right now render gray. These are NAV with no usable source, VNAV with no profile, or a mode your aircraft’s autopilot profile marks unavailable. AP, YD, and LVL also gray while the system has no power, its servos have failed, or the sim refused the engage. A key whose system is on stays live so you can always disengage. Pressing an active mode’s key reverts that axis to its default (roll or pitch hold), and LVL cancels everything and rolls the wings level.

Modes

• Lateral: roll hold, HDG, TRK, NAV, plus approach, go-around, and level modes. NAV annunciates its actual source: GPS, VOR, LOC, or back-course. GPS steering flies the flight plan’s turns without chasing a heading bug.
• Vertical: pitch hold, ALT with selected-altitude capture (ALTS), VS, IAS, VNAV with target-altitude capture (ALTV), glideslope and glidepath, go-around, and level.

VNAV works the way the book says. The VNAV key arms, and the descent leg captures it. The appropriate altitude capture arms beneath it, and the autopilot levels at the VNAV target. That target becomes the new altitude reference, independent of the selected altitude.

Annunciations

The AFCS status box across the top of the PFD shows active modes in green and armed modes in white. A capture flashes green for ten seconds. Losing the data behind a mode reverts that axis with a yellow flash.

An autopilot disconnect flashes yellow for five seconds (manual) or red until you acknowledge it (automatic). To acknowledge it, touch the annunciation or press BACK. Pressing AP re-engages, which also clears it. AFCS alerting is visual; there are no autopilot tones.

ESP (electronic stability protection) arms in the background while the autopilot is off. At the edges of the attitude envelope it nudges the controls back inside it. It engages the autopilot in LVL if the excursion persists.

With the autopilot engaged, speed protection guards the envelope instead. It acts below 1.2 times the aircraft’s clean stall speed, or above 95% of Vne. The autopilot then takes the pitch axis and trades altitude for speed, annunciating amber USP or OSP. This continues until the selected climb or descent is back within what the aircraft can sustain.

Takeoff / go-around follows your aircraft’s own TO/GA switch (X-Plane’s standard TO/GA command). There is no separate E3X button. It annunciates TO on the ground and GA in the air, and it does not disconnect an engaged autopilot.

Smart Glide

The Emergency window offers Smart Glide for an engine-out. Open it from the Main Menu, or from the data bar’s button if you have enabled it. Smart Glide picks the best reachable field and runway, flies Direct-To it, and tunes its frequency. It engages the autopilot at best-glide speed, annunciated GLD, and flies a pattern onto final. Without a working autopilot, the flight director shows the same guidance for you to hand-fly.

Holding the Direct-To key for two seconds activates it at once (see Hardware Bezels for what you can and cannot hold). Cancel Glide in the Emergency window asks you to confirm first. The E3X refuses Smart Glide on the ground.

Coupling to your aircraft’s autopilot

The E3X does not replace your aircraft’s autopilot. It drives it, the way the real unit does, and it adapts to what that autopilot can do:

• The E3X drives capable autopilots (a G1000 or GFC 500-class AFCS) in their own native modes. It commands the aircraft’s actual heading, altitude hold, and speed modes, and auto-detects what the AP honors. A per-aircraft autopilot profile, picked under Setup → Config → Airframe, can also pin the answer.
• Legacy autopilots get precise flight-director control of heading and vertical speed instead.

Either way, every mode only the E3X computes works: VNAV, GPS steering, glidepath, go-around, level. The E3X’s flight director does the thinking and the aircraft’s autopilot does the flying.