commissioning of the WAAS for public use, the FAA conducted a series of test and validation activities. Future
dual frequency operations are planned.
6. GNSS navigation, including GPS and WAAS, is referenced to the WGS-84 coordinate system. It should
only be used where the Aeronautical Information Publications (including electronic datnd aeronautical charts)
conform to WGS-84 or equivalent. Other countries" civil aviation authorities may impose additional limitations
on the use of their SBAS systems.
b. Instrument Approach Capabilities
1. A class of approach procedures which provide vertical guidance, but which do not meet the ICAO Annex
10 requirements for precision approaches has been developed to support satellite navigation use for aviation
applications worldwide. These procedures are not precision and are referred to as Approach with Vertical
Guidance (APV), are defined in ICAO Annex 6, and include approaches such as the LNAV/VNAV and localizer
performance with vertical guidance (LPV). These approaches provide vertical guidance, but do not meet the
more stringent standards of a precision approach. Properly certified WAAS receivers will be able to fly to LPV
minimnd LNAV/VNAV minima, using a WAAS electronic glide path, which eliminates the errors that can
be introduced by using Barometric altimetry.
2. LPV minima takes advantage of the high accuracy guidance and increased integrity provided by WAAS.
This WAAS generated angular guidance allows the use of the same TERPS approach criteria used for ILS
approaches. LPV minima may have a decision altitude as low as 200 feet height above touchdown with visibility
minimums as low as 1/2 mile, when the terrain and airport infrastructure support the lowest minima. LPV minima
is published on the RNAV (GPS) approach charts (see paragraph 5-4-5, Instrument Approach Procedure
Charts).
3. A different WAAS-based line of minima, called Localizer Performance (LP) is being added in locations
where the terrain or obstructions do not allow publication of vertically guided LPV minima. LP takes advantage
of the angular lateral guidance and smaller position errors provided by WAAS to provide a lateral only procedure
similar to an ILS Localizer. LP procedures may provide lower minima than a LNAV procedure due to the
narrower obstacle clearance surface.
NOTE-
WAAS receivers certified prior to TSO-C145b and TSO-C146b, even if they have LPV capability, do not contain LP
capability unless the receiver has been upgraded. Receivers capable of flying LP procedures must contain a statement in
the Aircraft Flight Manual (AFM), AFM Supplement, or Approved Supplemental Flight Manual stating that the receiver has
LP capability, as well as the capability for the other WAAS and GPS approach procedure types.

4. WAAS provides a level of service that supports all phases of flight, including RNAV (GPS) approaches
to LNAV, LP, LNAV/VNAV, and LPV lines of minima, within system coverage. Some locations close to the edge
of the coverage may have a lower availability of vertical guidance.
c. General Requirements
1. WAAS avionics must be certified in accordance with Technical Standard Order (TSO) TSO-C145(),
Airborne Navigation Sensors Using the (GPS) Augmented by the Wide Area Augmentation System (WAAS);
or TSO-C146(), Stand-Alone Airborne Navigation Equipment Using the Global Positioning System (GPS)
Augmented by the Wide Area Augmentation System (WAAS), and installed in accordance with AC 20-138,
Airworthiness Approval of Positioning and Navigation Systems.
2. GPS/WAAS operation must be conducted in accordance with the FAA-approved aircraft flight manual
(AFM) and flight manual supplements. Flight manual supplements will state the level of approach procedure that
the receiver supports. IFR approved WAAS receivers support all GPS only operations as long as lateral capability
at the appropriate level is functional. WAAS monitors both GPS and WAAS satellites and provides integrity.
3. GPS/WAAS equipment is inherently capable of supporting oceanic and remote operations if the operator
obtains a fault detection and exclusion (FDE) prediction program.
4. Air carrier and commercial operators must meet the appropriate provisions of their approved operations
specifications.

Navigation Aids

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