It seems that every bit of new aviation technology is initially made much more complicated and confusing for pilots to use than is necessary. For example, when GPS navigators first became available, every instructional course from the FAA or others would start out describing the constellation of GPS satellites, their orbital altitude and so on. Who cares? And what, as a pilot, can you do about those satellites anyway?
When GPS approaches were approved we all were bombarded with descriptions of and warnings about RAIM, or the lack of it, at our destination. As I recall, RAIM stands for something like "receiver autonomous integrity monitoring." It has to do with how many GPS satellites are in view, and their relative angles which can affect the navigation solution. If RAIM is not available, an approach-approved GPS won't go into the active approach mode. But, again, there is nothing a pilot can do about RAIM.
And now we have WAAS-wide-area augmentation system-that enhances GPS accuracy and, equally important, improves the ability to monitor the integrity of the navigation guidance. By now just about every pilot must know that with a WAAS-capable GPS navigator it is possible to fly approaches down to the same visibility and decision height minimums as on a conventional ILS.
But as soon as a pilot installs a WAAS navigator, or converts his existing Garmin 430/530 to WAAS capability, the unnecessary confusion starts. And I blame the FAA and the instructor community for this problem, just as they caused the confusion about previously introduced new technology.
In one paragraph I have told you all you really need to know to put your new WAAS GPS system to work. The box itself, and the instrument approach chart, show you everything you need to fly approaches with WAAS, and they do it automatically with no need for additional training.
When we're talking WAAS and GPS we are really talking about Garmin and its 430/530 system. The company has delivered more than 90,000 of its GNS 530/430 navigators over the past few years, and it uses the same basic operating system in the all-glass integrated G1000 cockpit that dominates the new piston and light jet market. Garmin's equipment and operating methods rule the world of IFR flying in personal airplanes, and also in an ever-expanding list of utility and business aircraft. It is the system that sets the standard because of its numbers in the fleet.
This is how difficult it is to use a Garmin WAAS navigator to fly an approach. First you press the procedure button and a list of available instrument approaches at your destination airport appears. You place the cursor over the approach you want to fly, enter it, and that's it. You're ready to activate the approach and fly it. WAAS has taken care of itself.
Once the approach is selected, the 530/430 tells you what type of approach it is. Most RNAV approaches-what used to be called GPS approaches-will show up as lateral nav (LNAV), and many of those will also have vertical guidance. If the vertical guidance is available, the glideslope needle on your navigation display will automatically give you fly up or down commands just like an ILS. That's all there is to it.
Many, if not most, ILS approaches in the country have an RNAV approach overlaid. What I do with WAAS is select the RNAV approach on the number one system that is coupled to my flight director and autopilot, and then put the raw data ILS signal on number two. The RNAV approach guidance is so much smoother than most ILS signals that it is easier for me or for the autopilot to fly. And when you get close to the runway the RNAV "glideslope" stays perfectly smooth and stable all the way to the pavement, while the real broadcast glideslope starts to bounce around.
But what if the RNAV approach has the vaunted LPV status? Nothing changes. You simply select the approach in the normal way and fly the signal to the published minimums, which are typically lower than for a standard RNAV approach. Yes, there is a WAAS satellite channel number printed on the LPV approach plate, but so what? You can't select it. It is stored in the 530/430 database and you don't need to do a thing.
The LPV navigation display is designed to look more like the angular deviation indication of a real ILS, but that makes no difference in the way you fly it. And the decision height on an LPV approach means exactly the same thing as it does on a normal ILS, so there is nothing to learn there. The only difference you will see compared to a conventional ILS is how smooth the GPS-WAAS guidance is. You will see that many of those excursions left and right that we have blamed on our poor flying skills in the past are really bends and warps in the conventional ILS signal, and they are gone with WAAS.
