RNAV and GPS Approaches: A Pilot's Complete Guide

Complete guide to RNAV and GPS instrument approaches. Covers LPV vs LNAV/VNAV vs LNAV, WAAS requirements, reading approach plates, RAIM, database currency, and flying a GPS approach step by step.

April 2026·10 min read read·Faraim Editorial

KEY POINT

RNAV approaches are now the most common instrument approach procedure in the US. Understanding the difference between LPV, LNAV/VNAV, and LNAV minimums — and when each applies — is essential for IFR pilots.

Area Navigation (RNAV) approaches have largely replaced VOR and NDB approaches in the US. Enabled by GPS (specifically WAAS — the Wide Area Augmentation System), RNAV approaches now exist at thousands of airports that never had precision approach capability. But they come with several variants and requirements that confuse many pilots.

The RNAV Approach Types

LPV: Localizer Performance with Vertical Guidance

LPV is the highest-precision RNAV approach. It uses WAAS to provide lateral and vertical guidance to minimums as low as 200 feet HAT and 1/2 mile visibility — comparable to a Category I ILS. To fly an LPV approach, your GPS must be WAAS-capable and the approach must be active (NOTAM'd and available). LPV minimums are listed in the RNAV (GPS) section of the approach plate.

LNAV/VNAV: Lateral Navigation with Vertical Navigation

LNAV/VNAV provides lateral RNAV guidance plus advisory vertical guidance (baro-VNAV). Minimums are typically 300-400 feet HAT. LNAV/VNAV requires a baro-VNAV-capable avionics system and may have altitude restrictions during high-temperature operations.

LNAV: Lateral Navigation Only

LNAV provides only horizontal guidance — it's essentially a non-precision approach. The MDA (Minimum Descent Altitude) rather than a DA (Decision Altitude) is used. A standard GPS receiver without WAAS can fly LNAV approaches, making this the most widely available RNAV minimums line.

LP: Localizer Performance (no vertical)

LP approaches are WAAS-based with precise lateral guidance but no vertical guidance. They exist at some airports where terrain or obstacles prevent LNAV/VNAV. LP minimums may be lower than LNAV due to the precision of WAAS lateral guidance.

WAAS and GPS Requirements

To fly LPV or LP minimums, your GPS must be a WAAS-capable receiver with current databases. WAAS improves GPS accuracy from ~15 meters to approximately 1-3 meters horizontally and 2-3 meters vertically. Non-WAAS GPS can fly LNAV approaches but cannot access LPV or LP minimums.

Reading an RNAV Approach Plate

An RNAV (GPS) approach plate looks similar to a VOR approach but has key differences:

The title says 'RNAV (GPS) RWY XX' — not 'VOR' or 'ILS'
Minimums are listed in rows: LPV, LNAV/VNAV, LNAV, and Circling
LPV shows a DA (Decision Altitude) — you decide at that altitude, not below
LNAV shows an MDA — you can descend to MDA and then fly level until visual or missed
The CDI (course deviation indicator) must be set to GPS for RNAV, not VLOC
Check the 'W' in the minimums box — if absent, WAAS is required for that line

RAIM: Receiver Autonomous Integrity Monitoring

Non-WAAS GPS approaches require RAIM — a GPS self-check that verifies enough satellites are available for the required accuracy. Before an IFR flight, RAIM must be confirmed available for the approach. WAAS-based approaches do not require separate RAIM checks because WAAS provides integrity monitoring.

GPS Database Currency

Under §91.175 and FAA guidance, GPS databases used for instrument approaches must be current (within the 28-day cycle) unless the pilot verifies the approach procedure hasn't changed. Using an expired database is technically permissible if you verify currency, but most operators maintain current databases — it's required by many FBO and charter operations.

Flying a GPS Approach: Step by Step

Load the approach in the GPS — select the airport, approach, and transition
Review the approach plate — identify the IAF, FAF, minimums, and missed approach procedure
Activate the approach — select 'Activate Approach' (or equivalent) when cleared for the approach
Fly to the IAF — GPS will sequence through the approach segments automatically
At the FAF — confirm CDI sensitivity has changed to approach mode (from ±1 NM to ±0.3 NM)
Fly final — track the CDI, cross-check with altitude, descend to MDA or DA
At minimums — if visual, land; if not, execute the published missed approach

Always brief the missed approach before descending on final. Knowing exactly what to do before you need to do it is the difference between a smooth missed approach and a rushed, dangerous one.