Plain English Meaning

A setting on the flight director that tells it to follow either a VOR radial or a localizer beam. Once armed and captured, it shows the pilot exactly how to steer to stay on that course.

Full Definition

A flight director and autopilot operating mode that commands the aircraft to capture and track a selected VOR radial or a localizer course. When engaged, the flight director computes lateral steering commands based on deviation from the tuned navigation signal and displays them on the attitude indicator, allowing the pilot (or autopilot) to fly the course precisely.