Range of VORs

[Reece Hunter]

All,

 

The other day, I was on my way to KRDD and I was told to proceed direct. However, it was not only until I was about 20 miles out at 9000 feet when the needle came alive. I was able to pickup other VORs from at least 50 miles in the same area at the same altitude so I was wondering if RDD is a different cl[Mod - Happy Thoughts]ification that is modeled in our beloved sim.

 

Have you guys ran into anything similar?

 

RH

[Keith Smith]

Yep, the reception range of VORs was severely limited a little while ago. Evidently, someone reported to Austin that they were able to receive a VOR from too far away, so he dialed it down....way too much.

[Reece Hunter]

Keith,

 

Fair enough. I thought it would be consistent throughout the sim but my recollection dictates otherwise. It originally seemed like another gem being modeled in the sim. It still holds true that VOR is line-of-sight correct?

 

Austin must fly GPS all the time nowadays.

[Wade Williams 877539]

I talked to Ben about this today. We were discussing the PEBLE3.SLI transition.

 

http://www.laartcc.org/charts/SAN-DP-PEBLE3.PDF

 

The last time I flew this route at 10,000, I did not receive the SLI VOR before PEBLE, and i had to blindly turn to the course. About 5 miles after PEBLE, I finally picked up the VOR.

 

Now the SLI VOR is a low-power VOR, giving it an effective range of somewhere around 40 miles, which is how it's defined in earth_nav.dat. in Ben's test, he picked up SLI about 5 miles before the turn, which is consistent with this data.

 

Now, he realizes that a low power VOR doesn't magically quit at exactly 40 miles. What he's interested in is some feedback from REAL WORLD. So, if someone has X-plane experiences where VOR reception is significantly different from what you've seen in the real world, please post in this thread. With some data, Ben is willing to tweak the "fudge factor" some.

 

I want to re-iterate - we need actual data, not "I'm certain this would be farther in the real world."

[Shawn Goldsworthy 925085]

This VOR thing is something that has annoyed me to the point of re-installing FSX. Well that and a few other things that Austin seems to have no intention of fixing. I'll go back when those bugs are sorted for me.

[Brian Ratledge 962606]

Same here Shawn.

 

Wade here are two examples that, IMO, do not need real world verification:

I can't receive PGY from TANNR on V186 at 5500ft.

I can't receive the localizer from the KINGS intersection on the LDA/DME-1 for runway 18 at KTVL.

 

I have not tried these on the very latest release. I can get you my version number if you need it.

[Wade Williams 877539]

Brian,

 

Thanks. Ben definitely sees the issue. In the case of SLI for example, even though it meets "the letter of the law" (i.e. received at 40 miles) he realizes that receiving the VOR 2 NM before you need it is a bit of a harrowing situation and likely not "real-world" behavior. It's unlikely the FAA would have a procedure that has the pilot receiving the VOR 2NM before a turn where it was needed.

 

So, the question now is...how do we decide on the "fudge factor"?

[Brian Ratledge 962606]

Wade,

I don't know what the fudge factor should be.

 

I would prefer to revert to the old setting until the problem is fixed. I would rather receive the navaids too early than too late.

 

Thanks for helping out.

[Keith Smith]

Wade,

 

Check out AIM 1-1-8.

 

Standard Service Volumes need only apply to aircraft on unpublished random routes. That is, a VOR with a 40nm service volume should work ANYWHERE within those 40nm, within the specified altitudes. However, and this is a BIG however, SSV's do NOT apply to airways or approach procedures. Therefore, to limit a VOR to its published service volume is a misrepresentation of how the navaid will operate in real life.

 

This doesn't answer the fudge-factor question, but a good start would be take into account the distances involved with airways and instrument procedures that utilize such aids.

 

Keith