Definition
The lowest altitude, expressed in feet above mean sea level (MSL), to which descent is authorized on the final approach segment of an RNAV (GPS) non-precision approach flown using lateral navigation only. Because there is no vertical guidance on an LNAV approach, the pilot levels off at the LNAV MDA and continues toward the missed approach point, descending no further unless the runway environment is in sight and the conditions of 14 CFR 91.175 are met.
Plain English
On a GPS approach without vertical guidance, this is the lowest altitude you are allowed to descend to while looking for the runway. You level off here and do not go lower until you can see the runway and meet the rules to land.
Context Anchor
Seen on RNAV (GPS) approach charts in the minimums section, often on a line labeled LNAV with an MDA value.
Derivation
LNAV stands for Lateral Navigation, meaning side-to-side course guidance only. MDA stands for Minimum Descent Altitude — the floor for descent on a non-precision approach. Together, the term names the altitude floor used when only lateral guidance is available.
Why Pilots Care
It sets the hard altitude limit for continuing the approach in instrument conditions before a missed approach must be initiated if the runway is not visible.
Analogy
Think of the LNAV MDA as a hard floor during that part of the approach. You may descend down to the floor, but you may not go through it unless you can see what you need to land safely.
Grounding Statement
On final approach in cloud, the LNAV MDA is the altitude where you stop descending and hold level until you either see enough to land or begin the published climb-away procedure.
Intuition Check
Do not read “minimum” as a goal to dip below. LNAV MDA is a lower limit: descend to it if cleared and established, but do not descend below it until the required visual conditions for landing are met.
Example Sentence 1
Cleared for the RNAV (GPS) RWY 3 approach, the pilot descended to the LNAV MDA of 660 feet and held that altitude while searching for the runway.
Example Sentence 2
We descended to the LNAV MDA and held altitude while looking for the runway environment.