Definition
An electronic flight instrument system that processes attitude, heading, navigation, and air data inputs and computes the pitch and bank commands needed to fly a selected flight path. These commands are displayed to the pilot as steering cues (typically command bars or a single cue) on the attitude indicator. The pilot can hand-fly the aircraft by keeping the aircraft symbol matched to the command cues, or couple the autopilot to the system so it flies the commands automatically.
Plain English
A system that figures out exactly how the aircraft should be pitched and banked to follow a chosen course or altitude, then shows the pilot a moving cue on the attitude indicator to follow. Match the cue and the aircraft flies the desired path.
Context Anchor
Seen during instrument flying on an attitude indicator or primary flight display, especially after selecting heading, navigation, altitude, or approach guidance.
Derivation
"Flight director" comes from the idea of the system directing the pilot — telling them where to point the aircraft moment by moment, the way a director gives cues to a performer. The pilot still flies; the system just shows what to do next.
Why Pilots Care
It lowers pilot workload during instrument approaches and enroute navigation by providing clear steering cues.
Intuition Check
Do not confuse the flight director with the autopilot. The flight director shows steering guidance; the pilot or autopilot still has to move the controls.
Example Sentence 1
On the ILS approach, she engaged the flight director and flew the command bars down to minimums.
Example Sentence 2
With the FDS active, maintaining the desired heading became much simpler in the clouds.