RNAV (GPS) APPROACH USING WAAS

WAAS was commissioned in July, 2003, with initial operational capability (IOC). Although precision approach capability is still in the future, initial WAAS currently provides a new type of approach with vertical guidance (APV) known as LPV. Approach minimums as low as 200 feet HAT and 1/2 SM visibility are possible,even though LPV is semi-precision, and not considered a precision approach. WAAS covers 95 percent of the country 95 percent of the time.

NOTE: WAAS avionics receive an airworthiness approval in accordance with Technical Standard Order (TSO) C-145A, Airborne Navigation Sensors Using the (GPS) Augmented by the Wide Area Augmentation System (WAAS), or TSO-146A, 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 20-130A, Airworthiness Approval of Navigation or Flight Management Systems Integrating Multiple Navigation Sensors, or AC 20-138A, Airworthiness Approval of Global Positioning System (GPS) Navigation Equipment for Use as a VFR and IFR Navigation System.

Precision approach capability will become available when LAAS becomes operational. LAAS further increases the accuracy of GPS and improves signal integrity warnings. Precision approach capability requires obstruction planes and approach lighting systems to meet Part 77 standards for ILS approaches. This will delay the implementation of RNAV (GPS) precision approach capability due to the cost of certifying each runway.