• Which the release of FS2020 we see an explosition of activity on the forun and of course we are very happy to see this. But having all questions about FS2020 in one forum becomes a bit messy. So therefore we would like to ask you all to use the following guidelines when posting your questions:

    • Tag FS2020 specific questions with the MSFS2020 tag.
    • Questions about making 3D assets can be posted in the 3D asset design forum. Either post them in the subforum of the modelling tool you use or in the general forum if they are general.
    • Questions about aircraft design can be posted in the Aircraft design forum
    • Questions about airport design can be posted in the FS2020 airport design forum. Once airport development tools have been updated for FS2020 you can post tool speciifc questions in the subforums of those tools as well of course.
    • Questions about terrain design can be posted in the FS2020 terrain design forum.
    • Questions about SimConnect can be posted in the SimConnect forum.

    Any other question that is not specific to an aspect of development or tool can be posted in the General chat forum.

    By following these guidelines we make sure that the forums remain easy to read for everybody and also that the right people can find your post to answer it.

FSX Creating a DME Arc Approach

R

Ramjett53

Messages
223
Country
us-idaho
I have tried and tried to create a DME Arc Approach similar to the VOR/DME-D Approach in Unalakleet (PAUN) Alaska. I imported the default VOR Approach, but it uses FSX created waypoints, not the actual named waypoints. Here is the current AIRAC chart from AirNav...

http://airnav.com/depart?http://155.178.201.160/d-tpp/1510/01253VDD.PDF

I created the SHMUK, HERLA, ZEPOK, COPAM, and MEBSY Terminal waypoints (EARMI already exists as an Enroute Waypoint). Using the default approach as a guide I used the exact same Transition Legs, but my approach looks absolutely nothing like the default one.

The ADE Manual casually mentions approaches, but Jon specifically says that creating more than simple approaches is beyond the scope of the manual. The link to JVILES' tutorial is excellent, but again, mostly simple approaches and I could not find a DME ARC example anywhere in the tutorial. How do I become better at creating anything beyond a simple straight in approach off a fix.

Another type of approach I have trouble with are the ones where the Missed Approach Procedure involves turning to intercept a VOR Radial and then proceeding direct to the VOR. I've tried using a VI leg, a CI leg, a CR leg, just about any leg I could think of. What sources I could find don't really explain what all the required data in those types of legs mean. Data like Theta, Rho, etc.

For instance, again using the VOR/DME-D PAUN Approach for my example, the first leg of the MAP is a climbing turn to the right to 2,000' to intercept the UNK VOR 214 Radial. The second leg is to follow the radial to the HERLA waypoint. If I use a CR leg it wants to know both the Course and the Theta Degree. Not sure what to put in these blocks. Not even sure which leg types to use.

A definitive step by step would be nice. One last thing...in the default DME Arc Transition, the words "DME Arc" appear as the first "leg". I see no way to add/create that leg entry.

Randy
 
Ramjett53 said:
snip-------------------------

The ADE Manual casually mentions approaches, but Jon specifically says that creating more than simple approaches is beyond the scope of the manual. The link to JVILES' tutorial is excellent, but again, mostly simple approaches and I could not find a DME ARC example anywhere in the tutorial. How do I become better at creating anything beyond a simple straight in approach off a fix.

Randy
Click to expand...

The approaches in FSX are based on the ARINC 424-16 Document. The SDK tells us we can purchase the complete specification which includes all definitions and illustrations of each leg type from the ARINC web site.

The SDK includes some information on what is required for different Leg types and their associated Required (R) and Optional (O) attributes.

If you do not purchase the ARINC 424 document then open an airport such as KHUT and look at all the DME Arc approaches. Using ADE you can make changes in the AF leg attributes pertaining to theta and rho to help understand drawing DME Arcs from a known NAVAID (VOR)
 
Thanks Jim,

Thanks for your reply. I will have to wait and see about the ARINC 424 doc. I tried using the default FSX VOR dme arc for PAUN as a "guide" to create the current VORDME-D Approach.

First, I simply renamed the default terminal waypoints to the real world named waypoint and then plugged those names into the legs descriptions. Looked terrible with one leg going 40 some miles into the distance (no, there wasn't another waypoint named the same way out there). It didn't even go to a fix, just a point in space and then a 45 mile leg back.

Second, I tried simply creating the real world waypoints and placing them directly over the existing FSX default waypoints. Then created identical legs using real waypoints. The arc was there, but if you look at the chart, the arc from SHMUK to HERLA extended past HERLA without even transiting the waypoint...but it was an arc of 16 DME. The second leg from HERLA to ZEPOK "started just before HERLA and again extended past ZEPOK, but at least this time it did transit the waypoints. It simply refused to "transition" to COPAM. That's where the 40 some odd mile leg appeared. I suspect the UNK VOR is not placed properly and my added waypoints are correct as far as long/lat. Maybe that's the problem.

Don't know where to go from here, so I created the RNAVs and other Approaches and left the default DME ARC in so at least there was an approach to fly if someone wanted the DME ARC.

Thanks again for your reply.

Randy
 
Randy

I took a look at PAUN.

FS fudged a little when they made the transitions by including 2 in 1. Look at the following pictures

Add a new Terminal waypoint SHMUK and click on the Transition and change the name to SHMUK. Refer to the picture and delete the 2nd AF leg, and set the DME ARC to 163. Note, The Transition will change to SHMUK once the work is completed.

fsscr001.jpg


In this picture change the IF to SHMUK

fsscr002.jpg


In this picture the Fix Ident will now be CF089, theta will be 269 (degree from the VOR). RHO means the arc is drawn in a circle 16NM from the VOR

ADE will change the name of the transition to SHMUK

fsscr000.jpg



You now have a single transition for SHMUK.

Do the same thing for D195P which will give you a new transition for HERLA.

Add a new T_Waypoint HERLA
Add a new IF leg (use the U key to move it up to its proper place after adding)
fix the DME ARC
delete the 1st AF leg and rework the second one with correct numbers
 
Last edited:
Jim,

I have no idea how to thank you for this. I used your instructions and created the DME Arc approach just the way it is on the charts...and I came to understand the entries that go in the various data spots on a leg.

In your example, 163 degrees is the degree to the starting point of the arc 16 miles from UNK. I see that now written on the chart. What I didn't realize before is those are the "course" and "distance" entries in the AF Leg to the arc starting point from the reference NAVAID, in this case UNK, not the course the aircraft flies. The Theta degree value of 269 is the ending point of the arc taken from UNK at a Rho distance of 16 miles.

Taking this "2 in 1" principle further, if I understand it. FSX actually (in the default installation) would show two transitions, one default DME Arc from the first default waypoint ending at CF089 and a second DME Arc approach starting at D195P and also ending at CF089. In the default GPS you could pick either transition and end up at the same point, CF089. Also, in a DME Arc in FSX, can I assume your aircraft is really flying from a point in space starting point (not a waypoint) to a point in space ending point (not a waypoint) relative to a fixed VOR or NDB. If so, why did the designers put the second DME Arc in? Perhaps there were two DME Arc Transitions in place at the time FSX was released?

Once I had the Transition and Approach set up the way you outlined I saved my airport and then decided to use the principles I learned from your post and actually create the DME Arc Transition from SHMUK to HERLA to ZEPOK in one Transition and use the second default D195P DME Arc Transition to create the left hand DME Arc Transition from waypoint EARMI. I added a second AF leg back in to the SHMUK DME Arc, ending the first AF leg where the second one begins (instead all the way round to ZEPOK (the old CF089). It worked perfectly once I understood the aircraft actually flies point in space to point in space relative to the UNK VOR and could care less what the actual waypoints are. So I now have two DME Arc Transitions, SHMUK and EARMI just like the current PAUN chart shows.

Again, I cannot thank you enough, Jim.

Regards

Randy
 
Randy

I am glad you understand the AF from my post. I used the single AF as the instruction but as you see multiple AF's under the DME ARC will work (with a duplicate) when the data is reference from the correct NAVAID

So I now have two DME Arc Transitions, SHMUK and EARMI just like the current PAUN chart shows.
Click to expand...

If you look at the approach chart there are 2 IAF's Initial Approach Fix not counting EARMI. One is SHMUK and the other is HERLA. You can but both in a Transition and then add both AF's like the default approaches but you still have to have 2 Transitions in the list (one named SHMUK and one named HERLA) so you can select each one in the ATC window. Anytime you see a IAF that is a Transition and ATC must see the name in its own Transition heading.

There is a 4th transition called COPAM. It goes outbound with a PI leg to the left and then back to whatever you made CF089. the default is UNK and FSX started it at the VOR and not the COPAM T_Waypoint which you would add a ghost waypoint.

You are correct, the arc starts and stops in space without knowing anything about the waypoint. You the Pilot is the one that needs the Waypoints for navigating the transition on the GPS.
 
Last edited:
Okay Jim, I see the HERLA DME Arc transition now. Completely glossed over that in my struggle to get SHMUK arc right. I have already created the COPAM and MEBSY waypoints and the EARMI and SHMUK transitions make a nice turn toward COPAM from ZEPOK (the previously default CF089). I'll work on adding the HERLA Transition and my PAUN should be good to go. I'll post here my results at getting the default Cessna to follow it.

Thanks again. I sincerely appreciate your help and guidance.

Randy

Edit: Success! I just finished a series of approaches based on the ones I created in ADE and all of them work as expected using the default Cessna and navigating with the AP in GPS mode, even these DME Arcs.

And I double checked the Procedures List in the GPS for each approach to make sure the Transitions appear in the list of choices by the correct name. For this one being discussed here I have the EARMI, HERLA, and SHMUK DME Arc options, as well as the Procedure Turn from COPAM (I started the Transition at UNK...but named it COPAM...to make sure the aircraft was established on the correct outbound course when it overflew COPAM).

Thanks again Jim, for your help with this, but more importantly helping me understand the various data fields of a Leg and what they mean.

Randy
 
Last edited:
You must log in or register to reply here.
Back
Top