Best Way to Load an Instrument Approach When Flying with Vectors

In the latest episode of the AviationNewsTalk.com podcast, a listener asked about the best way to load an instrument approach when flying with vectors to final. You can play it here on an iPhone or iPod, or on an Android or web browser.

I talked about it in far more detail in the podcast, so I encourage you to listen to it with one of the links above. But here's a short summary of my answer. There are two generic ways to fly an instrument approach.
1. Fly pilot navigation or pilot nav or own navigation, in which you fly to an IAF, initial approach fix, which is a starting point for an instrument approach.
2. Fly with Vectors. In the real world, that’s the way most pilots fly an instrument approach.

There’s actually a third way you can fly an instrument approach, which allows you, under some conditions, to fly directly to the IF, or intermediate fix, which is generally the next one you’d come to after the IAF. And once you’re cleared direct to the IF, a pilot can then follow the instrument approach on his own. But this questions is about flying an approach with vectors, so I’m not going to discuss that now.

When loading an approach, there’s a point in the process where you must choose one of the following: either one of the IAFs for the approach, or the word Vectors. And then you hit Enter, and continue loading the approach. And indeed, If you’re flying via own nav to an IAF, then you do indeed want to choose the IAF that you plan to fly to to start the approach, and load the name of that IAF into the GPS receiver as part of loading the approach. So if you are flying an approach by getting vectors from a controller, you might think well of course you should choose the word Vectors when you’re loading the approach. Now you can do that, and it will work much of the time, however it’s not always the best way to load an approach.

Here’s the problem with loading an approach with Vectors in some GPSs; the Garmin 430 is a great example. Historically when you loaded an approach with Vectors, most of the waypoints associated with the approach dropped off the moving map of the Garmin 430, and you were left with just two point, the Final approach Fix, and the Missed Approach point.

Now when you’re flying with vectors having just these last two points displayed is all you really need, if you’re flying over relatively flat terrain. However, if you’re flying over more hilly country and you’re flying an approach with multiple stepdowns on the approach, it’s becomes very difficult to figure out if the controller is vectoring you at a safe altitude, if you can only see the last two waypoints of the approach on your moving map. And to be fair, gradually over time, Garmin has added some additional points on some instrument approaches, so that you can see more than two waypoints when flying vectors to these approaches.

A perfect example is the LOC RWY 28L at KMRY, the Monterey Regional Airport on the Monterey Bay in central California. That approach comes in over mountains that rise over 5000 feet, and there are a series of five stepdowns to get down to the minimums for the approach.Imagine I’m receiving vectors from ATC and I’ve loaded this approach with vectors, and I just see the last three waypoints. Now imagine that I’m being vectored at 5,000 feet, but I can’t see CHRLE, YITUD or RODNE on my moving map. So as I’m being vectored onto the approach, it won’t be obvious to me whether the controller is bringing in inside, or outside of YITUD. And if I’m a properly paranoid pilots who always tries to verify that ATC has me at a safe altitude, I really need to know if I’m inside, or outside of YITUD. Because if I’m inside of YITUD at 5000, I know I’m at a safe altitude because the minimum altitude for that segment is 4600 feet. But if I’m being brought in at 5000 feet outside of YITUD, the minimum safe altitude is either 5300 feet or 6000 feet, depending upon how far outside TITUD the controller is vectoring me onto the approach. So if I can’t verify my location on the moving map, because I loaded the approach with vectors, I’m going to be pretty nervous. 

The common workaround has been to instead load the approach with an IAF….even though the controller is giving you vectors to the approach. So when I’m flying with Vectors to an approach, here’s what I do. I look on the chart for an IAF that gives me the longest straightest path to the airport and which doesn’t have a procedure turn. Then I load the approach with that IAF. That does two things for me. First, it puts all of he waypoints for the approach on the moving map, so I can see where I am relative to the waypoints. Plus, I’ll clearly see the distances listed for each leg of the approach.

Then I wait to see exactly where along the approach the controller is bring me in. I won’t always know that immediately, but over time, it will become clear, if for example, he’s bringing me onto the LOC RWY 28L approach somewhere between YITUD and RODNE. Now I can clearly see that he’s bringing me onto a segment where the mimimum altitude is 4600 feet, and so I know that I’m safe if he has me at 5000 feet. When it’s clear to me which segment they’re bringing me onto, I will press the FPL key to open the flight plan, and then I will activate the leg of the approach that he’s bringing me onto. To do that, I put a cursor on the second of the two points that define the leg, which is the point that’s closer to the airport. So in this case, if he’s bringing me in between YITUD and RODNE, I’ll put the cursor on RODNE, hit the Menu key, Activate Leg will already be highlighted for me, and then I’ll hit the enter key. This now makes that leg of the approach magenta on the moving map, and I can now get the autopilot to intercept that leg for me, and then have the autopilot continue to fly the approach from that point.

Now there is an exception, and that’s if I’m flying an approach in a Cirrus Perspective. The Perspective has a slightly different algorithm,and I end up doing things a little differently if I'm flying a Cirrus SR20 or SR22 with the Perspective glass cockpit handbook. If you fly a Cirrus and you're interested in knowing more about that contact me. In the meantime, please check out the Aviation News Talk podcast. You can play it in the Podcasts App on an iPhone or iPod or on an Android or web browser.