Detection distances for DME, VORDME, and TACAN

User Support Hub ATC, Traffic & NAVAIDs
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I’m flying Canada from coast to coast finding the detection distance/altitudes for each and every station. Here’s what I have as an example:

YUL VORDME Montreal 116.300 121nm@2500’ 183nm@3500’ 256nm@4500’ 309nm@5500’ 333nm@6500’

Altitudes are ASL. I fly only VFR hence the altitudes in thousands plus five hundred feet. I’ve flown over 81 hours in my Carenado YMF-5 using the onboard nav equipment and only have 29, of possibly hundreds across Canada, completed such as seen above.

My question:

Is/are there published distances in the sim that I could find? I ask for in the sim as opposed to published charts or 3rd party addons such Little Navmap.

Having fun doing this (kinda) but it can get a tad boring after awhile!

If there isn’t anything such as this then my goal will be to hit as many stations, only be Canada, as I can and perhaps publish my findings here for the aid of others.

Thanks for any help.

Bob

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I don’t belive so.

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Those distances seem pretty unrealistic to me. VOR distances are slant range, line-of-site, and generally speaking the service volume distance (the maximum distance that you should expect to receive a signal) for a high-altitude VOR is 130 NM.

Also, and I’m not joking here, cross-country flying is boring. Seriously, it can be. My first instructor used to say going up and coming down is the fun part of flying.

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If you open the MSFS Flight Planner and click on a navaid (VOR or DME) it will give you the range of the facility.

https://planner.flightsimulator.com

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Yeah, I’ve seen that distance mentioned in other publications but it is what it is in the sim.

This will be my fourth cross Canada trip but this time with a mission in mind as mentioned in the original post. Flying cross country using nothing but landmarks (I try not to use the in-sim map) I use Google maps to track where I am in regards to my flight path. Sometimes this can get a tad hairy when blown off course in places where there is a dearth of lakes, rivers, roads, or other easily recognized landmarks; Saskatchewan comes to mind. This is the time when I’ll slavishly follow the Trans Canada Highway no matter how much farther I have to fly!

What I’m saying is: cross country can keep you on your toes if you allow it.

And that shows what Island said above - the distances mentioned are 130nm but, again, it is what it is in the sim.

Thanks for the responses. I’ll just keep trucking on.

Bob

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This is also a real-world technique, and a very smart one, too! We call it IFR: I Follow Roads!

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Rails & rivers too!

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Maybe someone is interested in a few details I learned while implementing custom navaids (including VOR and DME) for my Twotter mod. The main motivation was that the unrealistic and “binary” ranges in the sim have bothered me for ages (binary, as in: 40.1 nm out = no signal, 40.0 nm out = perfect signal).

VORs are VHF signals, DME are UHF signals. Both have very high ranges as long as you have line of sight. It helps to be at altitude, because that expands your horizon. If there’s terrain between the station and your aircraft, you can still pick up the part of the signal that is diffracted or scattered towards you, but the range is greatly diminished. The effect of this terrain diffraction varies with frequency, so it affects VOR and DME signals differently.

The ranges of the VOR and DME parts of a VORDME can be drastically different. That’s not only owed to the frequency, but also to the nature of the signal. While VOR works as most people imagine (the station sends a continuous signal, an antenna in the aircraft receives and decodes it), DME is a two-way “connection” with a “handshake” of short signal bursts. Like a submarine, a sender in the aircraft (called interrogator) sends a “ping”, the DME station responds, and the aircraft calculates the distance based on the time between the ping and the response.

Wait, you say, a VORDME only has one frequency, how can it be VHF and UHF at the same time? The DME frequency is a lie. Somehow (don’t ask me how, I haven’t looked into every detail), the interrogator knows what frequency is tuned on your NAV radios. It looks up this VHF frequency in a table and gets a corresponding, totally different UHF frequency. This way, the pilot doesn’t have to operate yet another radio, eliminating a whole class of possibly dangerous mistakes. So if you see a DME-only station with a VOR frequency, that frequency is not in use at all. :smiley:

NDBs are way more interesting, but the question was only about VHF/UHF ranges.

Shameless plug: I’m not aware of any other aircraft that bothers to model the navaid ranges. If you picked up the 2020 Twin Otter from Aerosoft back in the day, you can see my attempt at a more faithful implementation in action.