Definition
A cockpit instrument that displays computed steering guidance to the pilot, showing the precise pitch and bank attitudes needed to fly a selected course, intercept a navigation signal, capture an altitude, or follow an approach path. The FDI combines an attitude indicator with command bars (or a single command cue) driven by the flight director computer; the pilot flies the aircraft so the symbolic aircraft aligns with the command bars.
Plain English
An instrument that doesn't just show you how the aircraft is flying — it shows you how it should be flying. You match the aircraft symbol to the command bars and you'll be on the correct path.
Context Anchor
Seen on the instrument panel during instrument flying, especially when using navigation equipment, an approach, or an autopilot system.
Derivation
From 'flight director' — meaning a system that 'directs' or commands the flight path — and 'indicator,' the cockpit display that presents that command. The name reflects its role: it doesn't just show information, it directs the pilot what to do.
Why Pilots Care
It reduces pilot workload and improves precision by turning complex navigation calculations into simple visual commands.
Intuition Check
Do not assume the FDI flies the airplane by itself. It is an indicator: it shows guidance for the pilot, or for an autopilot if one is engaged, to follow.
Example Sentence 1
After intercepting the localizer, the pilot centered the aircraft symbol on the FDI's command bars to stay on the approach path.
Example Sentence 2
When cleared for the missed approach, the FDI provided immediate pitch guidance for the climb.