localizer-type directional aid (LDA)

A NAVAID (navigational aid) used for non-precision instrument approaches with utility and accuracy comparable to a localizer but which is not a part of a complete ILS (instrument landing system) and is not aligned with the runway. The LDA course usually provides a more precise approach course than the similar simplified directional facility (SDF) installation, which may have a course width of 6° or 12°. The LDA is not aligned with the runway. Straight-in minimums may be published where the alignment does not exceed 30° between the course and runway. Where this alignment exceeds 30°, only circling minimums are published.

Mentioned in

non-precision approach

References in periodicals archive

LDA Localizer-type Directional Aid: An approach type using a localizer more than three degrees offset from the runway.

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The localizer beam must track within three degrees of the runway centerline (or else it's called a localizer-type directional aid, LDA) and is surveyed to provide at least 250 feet of obstacle clearance in the final approach area.

Approach secrets: we've never had so many approach choices to get into an airport. Which one to use? We help you sort out all the factors to find your answer

Why is this a Localizer-type Directional Aid (LDA) and hot an ILS approach?

Bank shot in Roanoke: when it all looks just about right, that's a clue to look for what's wrong. Nothing like an oddball approach to throw you off from the start

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