RNAV approaches, inclusive of those with LPV minima, have been designed and certified for use at numerous European, U.S.
LPV minima may have a decision altitude (DA) as low as 200 feet height above touchdown zone elevation with associated visibility minimums as low as 1/2 mile, when the terrain and airport infrastructure support the lowest allowable minima.
The SBAS generated angular guidance allows the use of the same approach design criteria that is used for ILS approaches. LPV minima take advantage of the high accuracy guidance and increased integrity that an SBAS (WAAS, EGNOS etc) provides to the basic GNSS signal. To enable use of LPV minima, the aircraft must be fitted with both an LPV capable Flight Management System (FMS) and a compatible SBAS receiver. As in an ILS, the angular guidance of an LPV approach becomes narrower and more sensitive as the aircraft approaches the runway. These extremely accurate augmentation systems can provide the required lateral and vertical approach guidance down to a decision altitude (DA) with provision for a slight "duck under" in the event that a Go Around is required. To provide the necessary accuracy to conduct an approach to LPV minima, the GNSS signal must be refined by a Satellite Based Augmentation System (SBAS) system, be it the Wide Area Augmentation System (WAAS), the European Geostationary Navigation Overlay Service (EGNOS) or another space based augmentation system. The FAS of an LPV approach may be intercepted by an approach transition, such as Precision-Area Navigation (P-RNAV), the initial and intermediate segments of an RNAV or RNP Approach, or via radar vectoring to intercept the extended FAS. It is defined vertically by the Threshold Crossing Height (TCH) and Glide Path Angle (GPA). The FAS is defined laterally by the Flight Path Alignment Point (FPAP) and Landing Threshold Point/Fictitious Threshold Point (LTP/FTP), in essence, an accurately defined runway threshold location and an equally accurate position on the extended centreline.
RNAV GNSS approaches that can be conducted down to LPV minima are characterised by a coded Final Approach Segment (FAS) data block. Whilst an ILS is a ground-based approach, necessitating the associated transmitters and antennae for each individual runway, the source for RNAV LPV guidance is the space based Global Navigation Satellite System (GNSS) which can be used to simultaneously provide the guidance to an unlimited number of aircraft conducting concurrent approaches at multiple locations. The fundamental difference between the two is the source of the guidance signals. Approaches to LPV minima have characteristics which are very similar to an Instrument Landing System (ILS) approach. Localiser Performance with Vertical Guidance (LPV) is a subset of Area Navigation (RNAV) Approach minima that are available at some locations in various parts of the world. Localiser Performance with Vertical Guidance (LPV) is defined as an Approach with Vertical Guidance (APV) that is, an instrument approach based on a navigation system that is not required to meet the precision approach standards of ICAO Annex 10 but that provides both course and glidepath deviation information.
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