Definition
The lateral-navigation-only minimum descent altitude published on an RNAV (GPS) approach chart. LNAV minimums apply when the aircraft is using GPS for course guidance only, with no vertical guidance from the navigation system. The pilot descends in a non-precision step-down manner to the published MDA and may not go below it unless the required visual references and other landing criteria are met.
Plain English
The lowest altitude you may descend to on an RNAV (GPS) approach when the GPS is only steering you side-to-side, not guiding you up and down. You level off at this altitude and look for the runway.
Context Anchor
Seen on RNAV (GPS) approach charts in the minimums section, usually on the line labeled “LNAV.”
Derivation
LNAV stands for Lateral Navigation. 'Lateral' comes from the Latin lateralis, meaning 'of the side.' The label tells you the GPS is providing side-to-side guidance only — no vertical path. Knowing this makes it clear why LNAV minimums are higher than minimums that include vertical guidance.
Why Pilots Care
They tell the pilot the exact point at which the approach must be discontinued if the runway is not in sight, protecting against obstacles and ensuring safe terrain clearance.
Intuition Check
LNAV minimums are not a target altitude to descend to automatically; they are limits you must not go below unless landing can be continued safely. LNAV does not provide approved vertical guidance, so do not treat LNAV minimums like a glidepath-based approach.
Example Sentence 1
Because the aircraft's GPS was not WAAS-capable, the crew briefed the LNAV minimums for the RNAV (GPS) Runway 27 approach.
Example Sentence 2
Reviewing the chart before the flight, she noted that the LNAV minimums required one mile visibility and an MDA 400 feet above the runway threshold.