These are all basic concepts of instrument flight. If there is a course reversal on an approach, in other words, if you have to get turned around and heading back towards the airport) you will be given an outbound heading to fly (away from a VOR) and an inbound heading back towards it. Outbound and inbound courses are just that. Theyre reciprocals of headings. In other words if you're flying on the 270 radial outbound from a VOR, your heading would be 090. And even with the extra approach types you need to know, having more approaches to pick from makes your flying safer and more convenient.A course is essentially a heading to fly. And given the increased choices, you have better options to land the direction you want at your destination. And with that choice, if you need to get low, you're almost always going to be better off with the ILS.Įither way, you have more choices today on the type of vertically guided approach you fly at almost every IFR airport in the US. If you don't have a WAAS capable GPS, you're going to be limited to ILS or LNAV/VNAV. If you're flying a GPS-based cross country, it's easy to program a GPS based approach into your system, and never have to worry about switching to "green needles" as your reach your destination airport. Beyond that, it depends on what you're more comfortable flying. Obviously, ILS and LPV approaches are going to get you the lowest on an IFR day. So, with the choice of 3 different types of approaches with vertical guidance, which one should you be flying? That means if you're using an airport with LPV only (no ILS) as your alternate airport, you need to use non-precision alternate minimums of 800'/2 miles, as opposed to the precision alternate minimums of 600'/2 miles. Since LPV approaches aren't considered precision approaches, you can't use precision alternate minimums for airports that only have LPV. Like an ILS, most LPV approaches will get you down to 200' above touchdown, with 1/2 visibility.īut like most things in aviation, where there's an upside, there's also a downside. That 700' of width at the threshold is the same as an ILS localizer at the threshold, but it doesn't get any tighter than that as you continue to touchdown. Unlike an ILS, which gets more and more sensitive (and difficult to fly near and below DA), the scaling on an LPV approach transitions to linear scaling as you approach the runway, with a total width of 700' (usually) at the runway threshold. There's definitely an advantage with LPV. The localizer antenna provides lateral guidance, and the glideslope antenna provides vertical guidance. And it does so with two ground-based antennas: a localizer antenna, and a glideslope antenna. The ILS is a precision approach because it provides both lateral and vertical guidance. In fact, the first time it was used by airlines dates back to 1938. ILS: The Only True "Precision" Approach For You So what's the difference between these three approaches, and which one should you be flying? Let's take a look at all three. Now with GPS, the number of approaches with vertical guidance has tripled, and to an extent, so has the confusion. Over the past several years, the FAA has created GPS based LPV and LNAV/VNAV approaches at thousands of airports across the US. And if you weren't flying an ILS, you were managing step-down altitudes on a non-precision approach.īut all of that has changed. Not long ago, you only had one kind of approach with vertical guidance: the ILS.
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