Autopilot & Flight Director Basics

A computed command display (V-bars or crosshair) on the attitude indicator showing the pitch and bank that would satisfy the selected modes. It moves nothing — you or the autopilot must fly to it.

A set of servos that physically move the controls; on most modern installations it flies to the flight director command bars, sharing the same mode logic and annunciator line.

It is superb at holding precise values for hours but has no idea what you actually meant — so it needs a clear briefing, constant supervision, and occasional firing (disconnect).

It teaches what each mode commands, keeps your scan honest, and reveals mode errors within seconds rather than miles.

ROL (roll/wings level), HDG (heading bug), NAV/GPSS (flight plan or VOR course), LOC (localizer), BC (back course), APR (approach), LVL (level).

PIT (pitch hold), VS (vertical speed), IAS/FLC (pitch for airspeed), ALT (altitude hold), ALTS/ALTV (preselect capture), GS (glideslope), GP (glidepath for LPV/LNAV+V).

White = armed (will capture later); green = active (controlling now). The white-to-green transition is the moment aircraft behavior changes — see it and say it.

Selecting VS to climb without setting a target altitude means no ALTS armed, so the autopilot climbs straight through the assigned altitude. Rule: set the altitude first, then the mode.

VS trades airspeed for vertical speed without limit, so it can pitch up and decay toward a stall while holding the number. IAS/FLC is safer because it protects airspeed.

Every time you touch the mode controller, say aloud what you selected and confirm the annunciator, e.g. 'Heading 210, HDG green; preselect 3,000, VS 500 up, ALTS armed white.'