Definition
A type of WAAS-based RNAV instrument approach that provides lateral guidance with accuracy and sensitivity similar to an ILS localizer, but no vertical guidance. The pilot flies the lateral course using GPS/WAAS signals and descends in steps to a published Minimum Descent Altitude (MDA), as in a non-precision approach. LP approaches are published only where terrain or obstacles prevent publication of an LPV approach.
Plain English
LP is a satellite-based approach that gives you a precise left/right course to the runway — as tight as an ILS — but no glide path. You follow the course laterally and step down to a minimum altitude, then look for the runway.
Context Anchor
Seen on RNAV instrument approach charts in the minimums section, often as an LP line of minimums.
Derivation
The name describes what it does: it provides lateral course performance equivalent to a localizer (the lateral component of an ILS), without the vertical component. The term anchors pilots in something they already know — the localizer — so they can predict how the course will behave.
Why Pilots Care
Allows precise lateral approaches to airports that lack a full instrument landing system, expanding access in marginal weather.
Intuition Check
LP does not mean an ILS localizer is being used. Performance does not mean aircraft performance here; it means the approach provides localizer-like left-right guidance.
Example Sentence 1
The RNAV approach into the smaller airport had LP minimums published instead of LPV because nearby terrain prevented a vertical glidepath from being certified.
Example Sentence 2
LP minimums were higher than those on the LPV version of the same chart.