Tips and Tricks #25
Practice Approaches with the GTN 750

Keith Thomassen, PhD, CFII
www.avionicswest.com

A common practice to maintain IFR currency is to do a round robin flight including approaches at a couple of airports and then returning for an approach at home. There are features of the current software in the GTN 750 (v6.4.1) that make such practice flights more user friendly and, in fact, unique among the GPS navigators of today. In an earlier Tip (#13) on “Practice Approaches” the difficulties of transitioning from one airport to the next were described using a GNS 530. [Note that all earlier Tips are available on my website www.avionicswest.com]. Here we’ll do a flight from Pueblo Colorado (KPUB) to Colorado Springs (KCOS), then to Freemont County (1V6) before returning home to Pueblo.

But first, let me point out that you can make a flight plan consisting only of the legs of an approach (no Enroute portion), which you might do to practice an approach to a nearby airport. On the ground at KPUB, select the PROC function from the home page and enter KCOS for the airport, and the ILS 35L with a PUB transition for the approach (see Fig 1). You can’t load this into a nonexistent flight plan, so your only choice is to Load and Activate it. Now, your active plan shows you going D-> PUB with the approach legs following.

Remember, Activate the Approach simply means go direct to the iaf chosen for the approach – nothing more. An approach is always “active” in the sense that when you come to it while sequencing through the legs of your flight plan it will be flown in that order. But since these legs come at the end of the plan you generally want to skip ahead (in your flight list) to fly them, which you could also do by using the D-> button for any waypoint, or Activate the Approach for the specific iaf. You could also activate one of the early legs.

Figure 1

Figure 1. A flight plan to Colorado Springs consisting only of the approach legs to KCOS.

Now to the round robin plan; it starts and ends at KPUB (see Fig 2). After creating the Enroute plan (pictures 1 and 2), touch KCOS and choose Load Procedures, then select the ILS 35L with PUB as the iaf and Load it (picture 3). The approach legs are added to the end of the flight plan. After flying this approach you’ll end at the holding pattern at ADANE (picture 4), and now want to add the RNAV (GPS) 29 approach to 1V6. There is a NoPt entry at FSHER, so we’ll choose it as the iaf.

Figure 2

Figure 2. Here is a round robin flight for practice approaches (1). Add an approach to KCOS by touching that tile (2) in the active plan, then selecting Load Procedures. Add the ILS 35L (3), which ends in a hold at ADANE (4).

Now here’s where the 750 is special. Go to the flight plan (Fig 2, picture 3) and select 1V6, then Load Procedures. When you choose the RNAV approach with the FSHER iaf and Load it, it is added to the end of your plan, after ADANE, which is not eliminated by this step! In other words, you added a procedure and did not wipe out the last one (ADANE is part of the previous approach). In other navigators if you add a procedure the old one goes away. Here, you can have two procedures in the plan. So in this case, you can stay in the hold at ADANE and plan your exit and route to the new approach. This is shown in Fig 3, where you can see in the plan, the end of the old approach and the first leg to FSHER of the new one. Again these approach legs are all added at the end of the flight plan, so you’ll have to jump ahead to fly these legs.

Figure 3

Figure 3. Two loaded approaches are in the Active Plan; the last legs of the missed approach at KCOS are followed by the approach to 1V6, shown on the plan list (1) and on the map (2).

Finally, in the latest software you can add a visual approach to any airport/runway. These are similar to a vector-to-final, except that they are a VFR procedure. To select a Visual, rather than the ILS of Fig 1, just scroll to the end of the list of approaches. Select runway 31 on the list in Fig 4, and note there is no transition choice. Again, since there is no flight plan you must Load and Activate this approach.

Figure 4

Figure 4. Visual Approaches now available in the GTN 750

In general, with a flight plan, you can either Load or Activate it. To later Activate it, select the V3NM leg and choose Activate Leg (don’t go direct to RW31 or you will loose the glideslope). Since there could be aircraft in the pattern here be vigilant for traffic. Plan to intercept this course in level flight below the glideslope for autopilot coupling.

There is also a feature that let’s you convert an IFR approach to a Visual by pushing a tile on the map as illustrated in Fig 5. There we are on an LPV approach to Rwy 15 at KLHM. When about 5 mi from the final at CODEY a Visual tile appears on the bottom corner of the map. Touch that tile and a screen appears that lets you choose, then Activate, a Visual to this runway (from either direction). You will get a warning here about terrain and obstacles, and that this is a 3° slope to a point above the end of the runway which is at the TCH altitude (threshold crossing height).

Figure 5

Figure 5. Converting an IFR approach to a Visual (VFR) approach with the tile (left screen). Activate by choosing the runway (right screen).

 

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