The second reason you could consider WAAS a quantum leap forward is accentuated by a recent FAA press release: “As of September 2008, there are now more Localizer Performance with Vertical Guidance (LPV) instrument approaches in the U.S. than there are Category-I ILS approaches.” As of January 2009, there were 1,445 published LPV approaches.
An LPV approach is based upon WAAS capabilities and could conceivably be to the same decision altitude as an instrument landing system (ILS). Most, if not all, are to a slightly higher decision altitude. Although not considered a precision approach by the FAA, like an ILS, it’s flown with what the FAA refers to as a “glidepath”—think glideslope—to a decision altitude. Considering that it’s theoretically possible to have an LPV approach at every airport in the country without each airport having to spend millions of dollars for an ILS installation, WAAS is a major improvement in general and commercial aviation utility.
We would be remiss not to qualify the previous statement. Any airport that wants an LPV approach will have to meet specific FAA requirements. For example, things like runway and approach lighting, runway length, airport property size, approach plane clearance, etc., are spelled out in detail. As a result, even though WAAS could support an LPV approach, some airports simply can’t qualify.
But if the airport can meet those criteria, then it’s possible to fairly quickly, easily and relatively inexpensively have a WAAS approach approved. The decision to install an ILS or a WAAS approach (and its required equipment and improvements) could equate to a difference of millions of dollars. Or much less if the airport already has most or all of the required improvements!
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