And, if we're using an autopilot or flight director, the lateral mode doesn't need to be reset. In this case, we don't need to cycle the CDI from GPS to VOR. In our example above, we did it by using the bearing pointers to monitor VHF Nav 1 and 2, all the way to the runway. Check out this this example of one we flew in Cortez, CO:Īs long as your VOR based bearing pointers show that you are on course, you can stay in GPS mode. The second way you can handle it is by monitoring the VOR using bearing pointers - like a RMI. And, if you have your autopilot connected, you'll need to re-set your lateral nav by pressing "APR" once you change the CDI source. And it also means you may need to make a course adjustment when you switch from GPS to VOR, because the VOR course may not be pre-selected. It's not the worst thing in the world, but it does require you to remember to switch before you cross the final approach fix. For the technical details, see AIM Chapter 1-2-3 "Use of Suitable Area Navigation (RNAV) Systems on Conventional Procedures and Routes" - paragraph "c." Make sure to read the "Notes" section.įirst, you can manually switch your CDI from GPS to VOR course guidance prior to the FAF. But, as long as you do that, you can continue to use GPS course guidance. So - the VOR must be operational, and you must have it tuned and displayed, and it must show that you are on course. But, it does allow you to use GPS for navigation, as long as you tune and monitor your position for final course alignment using VOR indications. The AIM prohibits you from using GPS (even if it's IFR approach approved) as the sole source of navigation on a VOR approach - one that doesn't say "or GPS" in the title. So what are you supposed to do? There are two ways to handle it. You have to manually set up the CDI as you approach the Final Approach Fix. Since most VOR approaches are no longer "VOR or GPS RWY XX", it means you can't use GPS as your sole means of navigation from the final approach fix inbound.Īnd unlike localizer or ILS approaches, when you load a VOR approach into the G1000, it won't automatically switch your CDI from the magenta GPS course to the green VOR course as you approach the Final Approach Fix (FAF). Especially when it comes to arcs and procedure turns.īut there's a catch. When you're flying a VOR approach, you can load the approach through your database and get advisory navigation from your GPS.Īnd that's really nice to have, because it can make navigating a VOR approach much, much easier. And if you have a fly-over waypoint on your chart (most missed-approach points are) your plane will fly directly over the point before making the next turn, no matter what angle you approach it from. On approach charts, they appear as a star with a circle around them. The only place this won't happen is with fly-over waypoints. Which is perfectly fine, it's just turn anticipation doing its job. In fact, we were more than a mile from ETL as we flew the approach. ![]() But because of the angle we were flying toward ETL, GPS turn anticipation kept us from getting close. On the LOC 09 approach at KTEX, ETL is the initial approach fix. Look at this example of an approach we were flying into Telluride: You'll experience this on both GPS approaches, and ground-based NAVAID approaches when you use GPS for guidance on the initial and intermediate segments. ![]() While it makes for smoother route segments, it can also leave you scratching your head. Your GPS calculates the most efficient turn on to your next course, and then 'cuts the corner' to make a smooth turn between course segments. Or get even close to them, for that matter. Most of the waypoints on a GPS approach are "fly-by" waypoints, which means you might not fly over them. Our examples are specific to the G1000 - but many TAA GPS and navigation systems are similar. Here are three common scenarios that can leave any pilot flying a technically advanced aircraft wondering what's going on. If you don't, it can bite you in the butt, and get you into a situation where you're saying "what's it doing now?!". That makes flying, and especially IFR flying, safer than ever before.īut at the same time, you need to know how to use the technology. Technically Advanced Aircraft give you an incredible amount of information in the air. Or more specifically, what the G1000 flight deck is doing. Do you see that frustrated look on our faces? That's us trying to figure out what our plane is doing.
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