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.

I don't necessarily agree with this statement. Yes, I know where I am in relation to a particular VOR, if I'm using that VOR myself for navigation. But if, during my pre-flight planning, I chose to navigate using landscape features (roads, railways, rivers) or maybe the magenta line on the GPS, and then I get a position report with reference to something else (a VOR, or maybe an obscure town), then I'm going to have a hard time figuring out whether something is a threat or not. And this is of course made worse if you're flying in unfamiliar airspace, or even in a foreign country, and the local pilot pronounces the local town name with a local accent. A lot of languages are far from phonetic.

So if I'm flying in class G and I hear a position report from another pilot and I can place it immediately, I might register it and do something with that information. But if I can't place that report immediately, I'm just going to disregard it. Like I said before, it takes me too much time, and too much heads-down time, to figure out what that report means in the first place and whether he constitutes a threat to me. And by the time I have figured it out, he has moved on anyway. Looking outside and assuming everybody flies around without making position reports is a far better strategy IMHO.

Edited to add - I'm only doing position reports in class G when I'm staying in a particular area for a longer time, and especially if I know my lookout is going to be less than optimal. For instance when doing a photoshoot, or when flying aerobatics. And even though this is class G and there are no guarantees, I'm always hoping that the FIS will inform other aircraft of my intentions if they happen to come near my location.

I am curious how you deal with the threat of aircraft who do not ‘announce their position’ ? There are many aircraft out there, some do not even have a radio ( shock , horror!) and the only realistic way to avoid getting close to them is to maintain a very good lookout utilising the mark 1 eyeball!

Agree with look out. To locate a position given relative to VOR will often take time looking at a map, paper or electronic.
Disagree with knowing every possible reporting point in preplanning for a long VFR flight into a densely inhabited area, especially with changing plan to avoid weather.
Pessimistic on lookout though. I was given an aircraft 3 miles and 500' distant by radar, and altered my course and height, saying what I was doing. We were both on radio, same frequency. But with low sun and haze visibility into the sun was poor, though good in every other direction. I never saw it.
I was lucky to get a warning from ATC in the US as I descended a C172 in ignorant formation below a Pa28, excellent visibility, and no other traffic near.

So I should ignore the information I get from those who do announce their position?

I must say I find this conversation a bit strange. I hear that it's important that I have my 'eyes out', but that is the whole point of my suggestion. I want a super simple way of judging where I am relative to aircraft I hear on the radio, without fiddling around with charts or ipads. Glancing at 2 numbers every few minutes does not seem too demanding, should I also not occasionally glance at the T's and P's for fear of hitting something?

As I have said, I am sure that I am by far the least experienced, and I am here to learn, but I wonder if I am hearing a bit of puritanism from those who don't like it to be too easy? In my other activities, there used to be similar discussions, eg insistence that AIS or VHF is dangerous for collision avoidance, or shock horror at navigating by GPS. All these concerns are real, and misuse or blind over-reliance can be dangerous, but that does not mean you should not make appropriate use of all the tools at your disposal.

It may also be worth adding that I think the environment I fly in may be a little unusual. When I am flying cross-country at 9,500', those around me are mostly professional pilots who are IFR capable, but who choose to fly VFR 90% of the time. They are typically also flying unpressurised and slowish a/c such as Caravans (because they are mostly delivering tourists to small airstrips) and we are all looking for the best groundspeed, VMC, O2 and healthy terrain clearance, so we all end-up between 9,500 and 11,500. They have shiny G1000 cockpits and rarely bother with local reference points, and when they do it's often not a name that means anything to me. So when they finish-up with 'and showing 130 degrees and 55 miles from the NAVEX', that's a super useful piece of data for me that I would like to use appropriately.

Do not think "black vs. white", please. ALL information you get - not only when piloting - is to be taken for what it is worth. For what YOU judge it worth, that is.

I treat position information on radio seriously, but keep my eyes out, relying on a rough idea of where they are. Will often respond stating my position, if we're not both getting radar info.
Safetycom is now much used where I fly, but I don't go head-in to plot positions on a map.
Height and intention are often more useful. I just hope the guy on a conflicting track 2000' above me doesn't have an engine failure and radio failure. :{

Let me turn the argument the other way around. Suppose, for a minute, that all VFR aircraft do position reports, that all these reports are dead accurate, that there is a common set of reference points (VORs, for arguments sake) that everybody knows and uses, and that they do this position reporting often enough so that the information stays relevant and accurate until they do the next position report.

You mention that you fly in the neighbourhood of 10.000 feet. At that altitude, the horizon is a little over 100 miles away, and you can hear transmissions of aircraft at 10.000 feet at double that distance - almost 250 miles away. In other words, you are going to hear all the position reports of all aircraft in an area that's about 200.000 nautical miles squared or well over 600.000 km^2 - approximately an area equal to the whole of France. Any idea how many VFR aircraft are out and about in France on a good day?

(For fairness sake, I'm assuming that this area is served by a single FIS/Unicom/whatever frequency, which is probably not the case. But that's hardly relevant. I'm just trying to get the point across that there's a vast area within line of sight, and thus within VHF range, at 10.000 feet.)

How many aircraft would be flying around such an area? Your post suggests that there's a fair bit of traffic about, and in that statement I'm assuming you're talking about the relatively close area. For arguments sake, let's be pessimistic and assume that there's 100 aircraft operating inside this 600.000 km^2 area. For position reports to be useful for other traffic, my gut feeling is that they should not be more than 5 minutes apart - your average GA spamcan covers at least 10 NM in that timeframe. So you now have to process 100 position reports every 5 minutes, or one every THREE seconds.

Can you do a position report yourself in less than three seconds? Is the frequency you're operating on really this busy with position reports? Can you interpret a position report within three seconds?

Heck, even if there's only ten aircraft on your particular frequency, then that still means a position report every 30 seconds. And each and every one of those needs to be interpreted, in addition to all the other mental tasks that you've got to perform as a pilot.

So for all practical purposes, position reports simply don't work, especially not for aircraft going from A to B at 100+ knots. So the vast majority of pilots don't make them in the first place, or at least not often enough to be practically useful. So you've got to assume that 99% of the traffic that you might encounter, has not made a position report at all. For the other 1%, is it worth spending an immense amount of mental energy interpreting their position reports? Or should your time be spent doing other things, like looking outside?

Position reports don't keep you safe. What keeps you safe is looking outside, TCAS/PCAS/Flarm or something similar, some form of radar/traffic information service, and the fact that the sky is really, really big and aircraft are comparatively very, very small.