Synthetic VOR/DME
 

I have just sent this as a future feature request to Garmin Pilot. I thought I might post it here to see if it makes sense to you lot and if anyone is aware of an exiting solution:


Where I typically fly, aircraft flying VFR in uncontrolled airspace report their position on the traffic advisory frequency, typically as range and bearing from a particular VOR/DME.

My aircraft does not have DME so I have no easy way judge the position of an aircraft relative to me and thus decide if there is a potential conflict. A simple solution would be for me to enter the VOR/DME location as a waypoint, and have an option to display range and bearing to that 'special' waypoint. In effect this would be using GPS to emulate a VOR/DME receiver. I don’t believe that I can currently do this unless I have the VOR/DME as a waypoint on an active flightplan which of course is not practical.

Any comments?

As a progamming job it is not hard. It isn't even impossible to design/conceive a dedicated device to do this, an Arduino could be sufficient, a Raspberry PI would be ample. The human interface to select/define the waypoint would take the most effort. But would it be legal to use such a non-certified device?

And didn't I hear (in some obscure corner of the www) that VORs are on the way out, though DMEs might remain as a backup against total GNSS failure?

As a pilot, I should think Skydaemon or any similar software package should give that info anyway, if the waypoint/VOR/DME is in the active flight plan?

Alternatively, just a rough best guess? For VFR outside Controlled Airspace it really makes no difference whether you're 10nm west of point X or 10.5nm west of it.

Exactly. But I also want a real flight-plan that tells me useful things like ETA at next waypoint. I could run 2 copies of Garmin Pilot - eg one on a phone that has the VOR/DME as the only active waypoint. But that seems daft when I am sure it could easily be done within the program on one device.

It does if I guess I am around 10 miles West of point X, and someone tells me that they are 11 miles and 290 degrees from point X.

The Garmin 430 has a cursor facility that gives bearing and distance of wherever the cursor is placed. “Target” doesn’t need to be in a flight plan but obviously needs to be set to “display...”

i don’t know Garmin Pilot, but as the 430 has been around for 30years and this is fairly common functionality I would be surprised if similar wasn’t already in the Garmin Pilot....

Yes, that is relatively easy to do in Garmin Pilot. Just touch the screen over a point and get the distance and bearing TO the point. Or use two fingers and place a line between aircraft and point. This is a certainly possible, but a bit fiddly usually involving a change of zoom level. It would be way easier if there was a window with distance and bearing from a designated point permanently shown.

Garmin 430 and family: "Direct To" the waypoint (VOR), then press the OBS button. Using the physical round dial (if fitted & connected) or the pop-up menu of the 430 (if not), to set the OBS value. The magenta line now shows the to/from bearings. Extrapolate the "scale" line/bar (lower left corner of the GPS map display) mentally on that bearing line and you know where you are vs. that other aircraft.

Having said that, I would not do this at all. If the aircraft is far away there's no conflict and by the time you are at his position he'll be gone anyway. And if there is a potential conflict, a simple bearing like this is way too inaccurate to take proper avoiding action. It's much better to be looking outside than to have your eyes in the cockpit trying to program the box.

Why not find the point on the chart (paper or nav display) and just estimate the approximate distance from that? There's absolutely no point in plotting distance to decimal places from a radio navaid in a VFR cruise outside CAS; in any case, if you're becoming concerned about the near proximity of another reported aircraft go eyes out, not IN.

Exactly. That's why I thought it would be nice to glance at 2 numbers that tell me all I need to know, then I know where the hazard is and can immediately get my eyes out. I don't want to be fiddling with a chart or ipad.

I think you would be better served improving your situational awareness without relying on electronics. You should always have an accurate idea of where you are relative to landmarks, navaids etc. If you hear someone make a position report based on a VOR/DME position you should be able to immediately visualise where they are and what, if any, conflict they may be. People tend to over read charts and try to overcomplicate the basics of good airmanship.

Sorry, no - you know where they've reported they were. If it's a matter of a few miles when potential closing speeds could be 240+kts, then we're talking rather less than 30 seconds between identifying a potential conflict and having to avoid it - time best used in a visual scan, rather than trying to identify a precise position in a dynamically changing environment. Note this advice has come from at least 2 people on this thread with a good few thousand hours each operating in Class G airspace at a variety of levels and speeds...

I don‘t know GarminPilot, but use ForeFlight and Skydemon. Both will show you bearing and distance when the VOR/DME is tapped on the map. I would be surprised if GP does not have the function already. RTFM maybe?

I only have 43 years of flying for a living in Class G and instructor ratings on both fixed wing and helicopters; and another four or five years of private flying before that, so I obviously still have a lot to learn.....

OK, OK, I don't want a quick and simple way to know my location relative to the standard reference that everyone else around me is using. I'll just keep gazing out of the window.

Where I fly it's easier just to get a Traffic Service.

But from a situational awareness point of view, I really shouldn't be out if I can't judge whether or not there is a risk from somebody who says he's 18 nm south of Biggin.

You were very much one of the 2 :) personally my FI students and test candidates manage to teach me something new on pretty much every flight!

It really isn't personal, just a communication confusion. If you know where you are, then using principles of Threat and Error Management means that you've always got a reasonable idea of where you are relative to the standard reference that everyone else is using - we both agree on that being important. It just really is simpler to have a good quick rough reference, trusting someone else's report of X.X miles from anywhere involves appreciating that their precise position changed as soon as their transmission finished. Bear in mind piston aircraft may cruise anywhere between 50-55 and 210 knots, before any wind effect!

Please don't think I am ignoring your messages, I am almost certainly the least experienced PPL here and I know that I have an almost infinite amount to learn. But I like to think I am pretty good at visualizing where I am relative to the 'landscape'. That comes from many years in charge of large boats. Nevertheless, I don't have an accurate running fix in my head and if someone gives me a position and direction of flight I felt it would be useful to know if they were ahead or behind or were likely to cross from left or right. But it seems that I am overthinking this, thanks for your inputs.

have you thought maybe some people maybe under thinking it? I’ve never heard anyone give there location in that way. But if they do then knowing where you are in similar terms is very sensible. The quickest way will be a readout as you asked. Very easy if you have a second GPS

Knowing where you are in relation to a VOR should come from the mental picture formed during thorough pre-flight planning and map study. Just as one should know about airspace around and above the route. It does become easier with more experience, releasing mental capacity once airborne.

However, the last thing we need is pilots in Class G becoming more reliant on hand held/ operated electronic devices that require them to be heads in/eyes down to lap level. As it is, it never ceases to amaze me how many pilots don't take avoiding action, or even show any acknowledgement of the presence of another aircraft, when they are bound to do so by the rules of the air. I can only assume it's because their lookout is totally ineffective. Either that or they don't know the right of way rules, which is less likely, seeing as we all have to pass the same air law exam.