Definition
An electronic flight instrument system that computes and displays steering commands to the pilot, showing the pitch and bank attitudes required to follow a selected flight path. The commands appear as command bars (or a similar cue) on the attitude indicator. The pilot flies the aircraft manually to keep the aircraft symbol aligned with the command bars, or the same commands can be coupled to an autopilot which then flies the aircraft automatically. Inputs come from sources such as the heading system, navigation receivers (VOR, ILS, GPS), and air data, processed through a flight director computer driven by mode selections made on a mode controller.
Plain English
A system that works out where the aircraft needs to point to follow the chosen route or approach, then shows the pilot a visual cue on the attitude indicator saying 'fly this pitch and bank.' The pilot just keeps the aircraft symbol matched to the cue, and the aircraft ends up where it needs to be. The same cues can also drive the autopilot.
Context Anchor
Seen on attitude indicators, primary flight displays, and autopilot control panels, especially during instrument flying, climbs, descents, course tracking, and approaches.
Derivation
The name describes the function plainly: it 'directs' the 'flight' by telling the pilot which way to steer. Worth noting because students sometimes assume a flight director flies the aircraft itself — it doesn't. It directs; the pilot (or autopilot) flies.
Why Pilots Care
It lowers pilot workload and improves precision when flying instrument approaches and holding assigned courses.
Intuition Check
Do not assume a flight director system flies the airplane by itself. It gives steering guidance; the airplane moves only if the pilot follows it or the autopilot is engaged to follow it.
Example Sentence 1
On the ILS approach, the captain hand-flew the aircraft by following the flight director system's command bars down to minimums.
Example Sentence 2
With the autopilot coupled, the flight director system commanded a climb to the assigned altitude.