![]() LPV minimums require dual WAAS receivers that are under TSO 145/146. WAAS-capable avionics do not automatically mean you are able to fly to an LPV minimum. Most WAAS receivers are installed under an STC. After installation, all equipment in the airplane must be tested for proper operation, including the autopilot, scaling and anything else impacted. There is a lot more required to a WAAS installation than can be conducted under a straight field approval. If I install WAAS-capable equipment, can I fly LPV approaches? The minimum descent altitude for an LP approach is 300 feet above the runway. LP approaches can only be flown by aircraft equipped with WAAS receivers. These approaches are needed at runways where, due to obstacles or other infrastructure limitations, a vertically guided approach (LPV or LNAV/VNAV) cannot be published. LP is an approach that uses the high precision of LPV for lateral guidance and a barometric altimeter data for vertical. ![]() It is similar to LNAV/VNAV except it is much more precise enabling a descent to as low as 200-250 feet above the runway. It stands for Localizer Performance with Vertical Guidance and can only be used with a WAAS receiver. The decision altitudes on these approaches are usually 350 feet above the runway. Aircraft without WAAS must have a VNAV altimeter. It provides lateral guidance from GPS and/or WAAS and vertical guidance from a barometric altimeter or WAAS. LNAV/VNAV is also a non-precision approach. LNAV procedures achieve a minimum descent altitude of 400 feet above the runway. It uses GPS and/or WAAS for lateral navigation, but with no vertical guidance. What are LNAV/VNAV, LPV and LP approaches? However, there are several countries working on similar space-based systems that will be compatible with WAAS avionics.Īll of those units should be compatible with what is in the United States. WAAS coverage includes the United States, from Alaska all the way down to Latin America and part of the Caribbean. The WAAS message improves the accuracy, availability and safety of the GPS. These correction messages are then broadcast through communication satellites to the airborne GPS receiver using the same frequency as GPS. Using this collected error information, a message is developed to correct any signal errors. The network of precisely surveyed ground reference stations is strategically positioned across the country including Alaska, Hawaii, Puerto Rico, Canada and Mexico to collect GPS satellite data. The WAAS Network uses over 25 precision ground stations to provide corrections to the GPS navigation signal. WAAS has an accuracy to within one to two meters. ![]() Satellite-based navigation fits within the NextGen framework and provides the same capability as a 60-year old Cat-1 ILS type of approach but to more runways. It stands for "Wide Area Augmentation System." WAAS is an extremely accurate navigation system that utilizes a combination of global positioning satellites and geostationary satellites to improve the GPS navigational service. The following is what you need to know about WAAS/LPV for corporate aircraft. On this approach, you can descend to as low as 860' MSL until you see the runway, or until you reach the MAP.I get a lot of questions about WAAS and LPV. LNAV stands for Lateral Navigation, and MDA as you now know, stands for Minimum Descent Altitude. Looking at the example below, the RNAV (GPS) RWY 34 at Newport Municipal, you'll see that under the minimums section there the words "LNAV MDA" are written. Under the minimums, you will see different lines of minimums you can fly (this will depend on the type of equipment you have onboard) and whether they correspond to a Decision Altitude or a Minimum Descent Altitude. To find MDA or DA, you'll look to the Minimums section toward the bottom of the chart. Now that you know the theory behind MDAs and DAs let's identify them on approach charts. But if the weather is at minimums, it's entirely likely that you'll be making your continue/go-around decision at DA. In practical terms, you typically descend out of the clouds and have good enough visibility to see your landing runway well before you reach DA. Here's how it works: as you descend down the electronic glideslope of an approach, as you reach DA, you look up, determine if you have the three requirements to land, and then make your decision, which is either 1) continue your descent down the glidepath and land, or 2) go missed and start climbing. ![]()
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