Display Screen
1. HDG (heading) Mode-Heading Preselect and Hold. When HDG and NAV activated simultaneously, enables dual mode intercept - autopilot operates in heading mode to automatically intercept and track selected course or localizer; at which point HDG extinguishes.
2. Control Wheel Steering (CWS). Allows you to hand-fly the aircraft and then let the autopilot takeover to hold the existing turn rate and vertical speed.
3. NAV mode (coupled navigation). Automatically intercepts and tracks en route NAV signals (VOR/GPS) or LOC (REV for backcourse). 3-level gain selection for NAV mode is automatic. When APR is lit (simultaneous with NAV), indicates high gain localizer mode for high sensitivity coupled approach. Flashing NAV or REV annunciates course deviation of 50% or more. Selecting APR increases gain sensitivity for VOR or GPS approaches.
4. GPSS (GPS Steering). Integrates A/P with GPS Navigator function, which outputs roll steering commands. GPSS does not follow a CDI needle movement; it acts on direct roll steering commands from the Navigator for extremely accurate, hands-off GPS navigation. See separate data sheet for details.
5. TRIM and Up/Down Arrows. Annunciate motion of auto trim or manual electric trim, if equipped; if not equipped, annunciates out-of-pitch-trim condition.
6. Pitch Mode. Includes VS, indicating vertical speed control has been selected, ALT indicating altitude hold is engaged, capturing existing altitude when activated; and GS, indicating glideslope coupling is armed and/or active. In altitude hold mode, altitude can be adjusted (trimmed) in 20' increments using VS knob.
Buttons/Knob

7. Mode Selector Buttons. HDG (heading hold and heading pre-select*), NAV (tracking VOR route or select twice for GPSS), APR (higher gain for LOC/VOR and GPS approaches), REV (LOC backcourse), ALT (altitude) hold, and VS (vertical speed) command .
8. VS Knob. Dials digital vertical speed in 100' increments..

* Operational if heading system is installed and active.