Localizer performance with vertical guidance
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 usually similar to those of a Type I instrument landing system (ILS), that is, a decision height of 200 feet (61 m) and visibility of 1/2 mile. Although precise and accurate, it is still considered a Non-Precision approach. According to the Instrument PTS, you may use a GPS approach down to LPV minimums to substitute a precision approach.
Examples of receivers providing LPV capability include (from Garmin) the GTN 7xx & 6xx, GNS 480, GNS 430W & 530W, and the post 2007 Garmin G1000 with GIA 63W. Various FMS models, GNSS receivers and FMS upgrades are available from Rockwell_Collins (e.g.). Most new aircraft and helicopters equipped with integrated flight decks such as Rockwell Collins ProLine (TM) 21 and ProLine Fusion (TM) are LPV-capable. 
LPV is designed to provide 25 feet (7.6 m) lateral and 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 metres in its operational history. As of April 2, 2015 the Federal Aviation Administration has published 3,534 LPV approaches at 1,725 airports. This is greater than the number of published Category I ILS procedures.
- "LPV Approach – Localizer Performance with Vertical Guidance". aasfms.com. 2008. Archived from the original on 2009-01-01. Retrieved 2010-02-07.