Definition
An indication on the localizer course deviation indicator (CDI) telling the pilot that the aircraft is right of the localizer centerline and a left correction is required to reintercept the course. The CDI needle deflects to the left of center, showing the position of the localizer course relative to the aircraft.
Plain English
The instrument is telling you: 'the runway centerline is off to your left—turn left to get back on it.' You're currently right of where you should be.
Context Anchor
Seen on the course indicator during an ILS approach when tracking the localizer toward the runway.
Why Pilots Care
Misreading a fly-left indication—turning the wrong way—takes the aircraft further off course and, on an ILS, away from the protected approach path. Correct, prompt response keeps the approach stable and safe.
Intuition Check
Fly-left does not simply mean “turn left and keep turning.” It means “correct left until the indication centers, then stop the correction and track the course.”
Example Sentence 1
Established inbound on the localizer, the pilot saw a slight fly-left indication and made a small heading correction to recapture the centerline.
Example Sentence 2
When established on the approach, a fly-left indication means the aircraft has drifted right of the localizer.