The FAA announced this week that it will permit aircraft using the GPS-based Wide Area Augmentation System (WAAS) to descend lower than currently allowed as they approach an airport before deciding whether or not to continue on and land when they begin publishing new procedures late this year. It's a decision, says the Aircraft Owners and Pilots Association (AOPA), which opens the door to precision all-weather approaches at thousands of general aviation airports.
"AOPA has been a strong supporter of WAAS for more than a decade," said AOPA President Phil Boyer. "We have urged both Congress and the FAA to press ahead with the program because it improves air safety by providing precision vertical guidance needed, especially in poor weather conditions. And it makes better use of the nation's system of airports because thousands that currently may only be used in good weather can become all-weather capable."
Currently, it costs the federal government between $1 million and $1.5 million per runway end to install the current ground-based radio navigation system, known as an instrument landing system (ILS). By comparison, mapping and publishing a new WAAS-based instrument approach procedure with vertical guidance (WAAS LPV approach) costs about $50,000.
Right now, pilots flying a WAAS LPV approach can descend no lower than 250 feet above the surface of the airport. When the new procedures are published, they will be allowed to descend to 200 feet above the airport.
"Fifty feet is the height of a five-story building," said Boyer. "It can be the difference between seeing the airport and being able to land or having to divert to another airport."
WAAS detects and corrects minor errors in signals from the Global Positioning System (GPS) and enables precision navigation. The WAAS-corrected signal provides the same precision as an ILS everywhere and at every altitude. That enhanced precision allows the FAA to publish WAAS LPV approaches to any runway and provides ILS-like minimums to runway ends that meet current ILS clearance requirements.
"The one thing we would still like to see the FAA do is recognize WAAS LPV approaches for the precision approaches they are, especially in light of today's announcement," said Randy Kenagy, AOPA's senior director of advanced technology. "The agency currently regards them as nonprecision approaches with vertical guidance and expressly forbids their use on an instrument rating checkride as the required precision approach. AOPA questions that thinking, especially if the approach has the same minimum standards as an ILS approach."
Although the FAA has not announced their implementation plans, AOPA expects that the first WAAS LPV approaches with the improved minimums are likely to be overlays for existing ILS approaches, most of which are at America's air carrier airports, with new stand-alone LPV approaches with lower minimums to follow. Although these approaches are "quick wins," adding to the number of LPV approaches, the real benefit to general aviation will come at airports or runways that do not currently have an ILS.
"While the FAA's announcement is most welcome, there is more work for everyone to do," Boyer concluded. "The FAA needs to set a brisk pace for approving more vertical guidance WAAS approaches and to create a set of standards that recognize the needs and realities of smaller airports. And owners need to upgrade to WAAS-enabled avionics to take advantage of the new approaches and to show the government that the billions of dollars already spent on WAAS was a wise investment - one worth continuing to fund."
The more-than-407,000-member Aircraft Owners and Pilots Association has represented the interests of general aviation pilots since 1939 and was one of the earliest proponents of civilian use of GPS. General aviation includes all flying except the scheduled airlines and the military. Nearly two thirds of all U.S. pilots, and three quarters of the GA pilots, are AOPA members.
Editors: AOPA provides two important resources for covering general aviation news - an online newsroom ( www.aopa.org/newsroom/) and a television studio and uplink ( www.aopa.org/satellite/). Contact us for more information.
March 7, 2006