FAA Instrument Rating Airplane (IRA)IFR Procedures and ChartsHard
An RNAV (GPS) approach chart depicts both LNAV/VNAV and LNAV minimums lines. The pilot's aircraft has an IFR-approved GPS receiver but no WAAS capability and no approved barometric VNAV system. Which minimums must the pilot use for this approach?
- ALNAV/VNAV minimums, since they provide lower minimums and are always preferred when available
- BThe pilot may choose either line at their discretion, since both are based on the same lateral GPS guidance
- CCircling minimums only, since vertical guidance is unavailable without WAAS
- DLNAV minimums, since the aircraft lacks the vertical guidance capability required for LNAV/VNAV
Show answer & explanationAnswer & explanation
Correct answer: D. LNAV minimums, since the aircraft lacks the vertical guidance capability required for LNAV/VNAV
LNAV/VNAV minimums require an aircraft system capable of providing approved vertical guidance, such as WAAS or a certified baro-VNAV system. Without either capability, the pilot must use the LNAV-only minimums, which do not require vertical guidance and rely solely on lateral GPS navigation with a stepped-down MDA.
Why the other options are wrong
- A. LNAV/VNAV cannot be used without the required onboard vertical guidance equipment, regardless of preference.
- B. Equipment capability, not pilot preference, determines which minima may legally be used.
- C. Circling is not required simply because vertical guidance is unavailable for a straight-in LNAV approach.
LNAV vs LNAV/VNAV Minimums
LNAV/VNAV minimums provide a decision altitude with vertical guidance and require WAAS or approved baro-VNAV equipment; LNAV minimums use only lateral GPS guidance to an MDA and require no vertical guidance system.
- LNAV/VNAV requires WAAS or certified baro-VNAV avionics
- LNAV minimums use MDA with no vertical path guidance required
- LNAV/VNAV typically has lower minimums than LNAV due to vertical guidance
- Equipment capability, not pilot choice, dictates eligible minimums line
Memory trick: No WAAS, no Vertical — stick with LNAV's level.