Localizer Performance with Vertical guidance (LPV) are the highest precision GPS (WAAS enabled) aviation instrument approach procedures currently available without specialized aircrew training requirements, such as Required Navigation Performance (RNP). Landing minima are similar to the Instrument Landing System (ILS), that is, 200 feet Decision Altitude and 1/2 mile visibility. The aircraft avionics must support LPV. Examples from Garmin are the GNS 480, GNS 430W, 530W, and the Garmin G1000.
LPV is designed to provide 16 meter horizontal accuracy and 20 meter vertical accuracy 95 percent of the time. Actual performance has exceeded these levels. WAAS has never been observed to have a vertical error greater than 12 meters in its operational history.
As of January 15, 2009 the Federal Aviation Administration has published 1,445 LPV approaches at 793 airports. This is greater than the number of published Category I ILS procedures.