FAA Instrument Rating Airplane (IRA)IFR Procedures and ChartsMedium
A pilot is preparing for an RNAV (GPS) approach. The approach chart shows both LNAV/VNAV and LNAV minimums. The aircraft is equipped with a WAAS-enabled GPS. Which minimums are the pilot authorized to use?
- ALNAV/VNAV minimums, as WAAS provides vertical guidance.
- BBoth LNAV/VNAV and LNAV minimums, depending on pilot preference.
- CLNAV minimums only, as they are less restrictive.
- DNeither, as RNAV approaches require specialized certification beyond WAAS.
Show answer & explanationAnswer & explanation
Correct answer: A. LNAV/VNAV minimums, as WAAS provides vertical guidance.
A WAAS-enabled GPS provides the necessary vertical guidance to use LNAV/VNAV minimums, which offer lower minimums than LNAV-only due to precision vertical guidance.
Why the other options are wrong
- B. While a pilot can choose LNAV, they are authorized for LNAV/VNAV if their equipment supports it.
- C. LNAV minimums are less restrictive in terms of equipment, but not necessarily better for the pilot if LNAV/VNAV is available.
- D. Incorrect. WAAS-enabled GPS is specifically designed for these types of approaches and provides the required certification.
RNAV (GPS) Minimums - WAAS
WAAS-enabled GPS allows pilots to use LNAV/VNAV minimums on RNAV (GPS) approaches, providing both lateral and vertical guidance.
- WAAS enhances GPS accuracy and integrity.
- LNAV/VNAV provides vertical guidance.
- LNAV provides lateral guidance only.
- WAAS enables lower minimums (LNAV/VNAV, LP, LPV).
Memory trick: WAAS gives you Vertical Accuracy, so use the VNAV!