Hornet Course Accuracy?

[1Wolf]

Are there known issues with the Hornet's accuracy regarding course and waypoints?

I was playing around with with the Course selection knob, offset waypoints, and various instrument approaches on the NTTR map around the Tonopah Test Range airfield and I was really getting "weird" results.  I'm a little confused so I thought I'd ask.

If I reference the approach plates provided for the Tonopah Test Range field the ILS approach is course 321/141.  However, the ILS feathers on the DCS NTTR map are 157/337.  Ok...at this point I was assuming that either the included approach plates or the ILS feathers on the DCS NTTR map were wrong.

So then, in the mission editor I set a waypoint dead center of the runway and measured out exactly 18nm in a straight line and the course to the runway was indeed 157/337 on the map.  So I set another WP there at 18nm southeast on the 157/337 approach course.

I hopped in the hornet and I pulled up the waypoint for the field.  I set a course off the waypoint of 337/157 in the hornet and was surprised to find that the course line was off considerably.  I expected it to pass right through that waypoint I set on the 157/337 approach course.  I had set a waypoint 18nm in a straight line 157 from the airport and then, in the hornet, set a course of 157 off the airport waypoint and I expected the line to pass through the waypoint and it didn't.  I started moving the course knob until it lined up with the waypoint line and it was closer to 325 instead of 337.

So then I set an Offset waypoint 18nm on a bearing of 157 from the airport waypoint.  Once again, that was yet in a different spot.

So, in summary, I set a waypoint in the mission editor exactly 18nm course 157 from the airport, a course of 157 through the airport waypoint in the hornet, and an offset waypoint from the airport to bearing 157 and distance 18nm.  I expected them all to be at least close and they weren't.

Also, is it normal for the included approach plate ILS course to be that far from the DCS NTTR ILS course?

Maybe I'm just misunderstanding these things in the hornet or DCS or maybe there are a series of known accuracy bugs that I wasn't aware of.  Thanks

[Swift.]

Are you confusing true and magnetic bearing perhaps?

[Frederf]

Magnetic v. true heading. Tonapa runway isn't 157, it's 144. I mean it's both, but in a magnetic-scheme airplane with magnetic-scheme published approaches it's the other one. The editor is in ruler direction which means not so much magnetically. Expect a 12-14° offset between the two systems depending on the date and where you are on the terrain.

[1Wolf]

Thank you.  That cleared up some of my confusion.  The True vs. Magnetic was definitely confusing me.

However, I am still a little confused about a couple things.  I've included some screenshots to help illustrate my question.

I've setup a Hornet to be 18nm out from TNX on approach to RWY 32.  You can see the ILS feathers label the true course to the runway as 337.

Here you can see from the HUD of the Hornet.  Flying a magnetic course of 325 right down the runway.

The approach plate lists the approach course as 321.

 

Below is a screenshot of the HSI from the Hornet on approach as above.  Note that I have a course set to 325 and the hornet is right on the line.  I also have an offset waypoint set to 18nm on a MAGNETIC bearing of 145 (325 - 180 = 145) so the offset waypoint should be right on that line.  Its not.  Its way off to the right of the HSI.

So then I tried setting the offset waypoint to 18nm on a TRUE bearing of 145 (325 - 180 = 145) and that one was way off too.

So I guess I just have 2 questions.

1) For the runway course, is it the approach plate or the runway orientation in DCS that is off?

2) For the offset waypoints, is that a known bug?  One of those offset waypoints should have ended up on that course line.

[Tholozor]

The magnetic variation will be different depending on the year the mission is set to in the editor. The approach plate in the kneeboard is only truly effective for the year it was published.

[1Wolf]

Thanks.  That explains the approach plates.  I'm assuming DCS includes Nevada area approach plates that were published at various times, and therefore, some are more accurate than others.  I set up approaches at several airports with included approach plates and found that some were accurate, some were not.  So you're explanation makes sense.

The offset waypoint issue still seems wrong though.  In those screenshots I included I set up offset waypoints using both True bearing and magnetic and neither of them appeared where I think they should have (Unless my understanding of the way the offset waypoints works is wrong, which is entirely possible).

[Swift.]

Offset waypoints are super unreliable right now, I only still use them because I'm trying to catalogue the bugs that appear every flight with them.

Also remember the approach course isn't necessarily the same as the runway heading.

[1Wolf]

Thanks!  At least now that I know that they are unreliable I won't be constantly fiddling around with them trying to figure out what the heck I'm doing wrong.  Thanks!