Definition
An instrument approach procedure that uses a Localizer-type Directional Aid for lateral guidance, designated with the identifier letter 'B'. The letter 'B' is assigned because the approach does not meet the alignment or descent criteria required to be named for a specific runway, and it is the second such non-runway-aligned approach (after 'A') published at that airport. An LDA provides course guidance similar to an ILS localizer but is not aligned with a runway centerline within the standard tolerance.
Plain English
An approach that uses a localizer-style ground signal to guide you toward the airport, but the course doesn't line up straight with a runway, so it gets a letter name (B) instead of a runway number. The 'B' just means it's the second approach of this kind at that airport.
Context Anchor
Seen in the title area of an instrument approach procedure chart, such as when selecting, briefing, or flying an approach.
Derivation
The 'B' follows a long-standing FAA charting convention: when an approach is not aligned with a runway, it is lettered alphabetically (A, B, C...) in the order it was published, rather than numbered after a runway (e.g., LDA RWY 6).
Why Pilots Care
Provides a usable approach path at airports where terrain or obstacles prevent a straight-in localizer or ILS alignment, increasing landing options in low visibility.
Intuition Check
The B does not mean runway B, and it does not mean a second version of the same runway approach. It is a chart letter showing this is a circling-only approach procedure.
Example Sentence 1
Because of the ridge east of the field, the only published procedure into Aspen-style terrain might be the LDA-B, requiring a circle to land on Runway 15.
Example Sentence 2
Minimums on the LDA-B were higher than a standard ILS because of the angled final approach segment.