Plain English Meaning

A landing-aid radio beam, like the one used in an ILS, but pointed at an angle to the runway instead of straight down it. It guides the pilot toward the airport, but a turn to line up with the runway is needed near the end of the approach.

Full Definition

A ground-based navigation facility that provides lateral course guidance to a runway, using equipment of the same type as an ILS localizer, but with the course not aligned with the runway centerline. Course alignment offset from the runway centerline is typically greater than three degrees, which prevents the facility from being designated as a localizer. An LDA may or may not be equipped with a glide slope; when it is, the approach is published as an LDA with glide slope.