I want to fly at 3000ft IFR from Royan to Toussus le Noble.
Autorouter won’t find any route.
The issue is that Eurocontrol refuses small legs (depending on where the leg is, small can mean 10NM or 50NM or maybe something else).
Out of controlled airspace, flying IFR is legal (at least in France), provided that you file a flight plan, and Eurocontrol’s refusal does not seem to have any legal basis.
The workaround is to create intermediary waypoints., but Autorouter does not seem to be able to create any.
My Skydemon and handmade solution:
-(FPL-FTEST-ZG -C172/L -S/S -LFCY1200 -N0100A030 DCT 4602N00041W IFR DCT ABSIE DCT 4715N00007W DCT 4721N00004E DCT 4725N00014E DCT NIMER DCT 4736N00026E DCT 4741N00029E DCT 4750N00033E DCT 4757N00036E DCT 4806N00040E DCT BENAR DCT ROMGO DCT 4826N00104E DCT 4830N00118E DCT BANOX DCT EPR/N0100A015 VFR RBT DCT 4843N00207E -LFPN0300 -)
is accepted, though a computer would certainly be able to find a better routing.
Entering that sort of flight plan in the G1000 is another story…
I commence VFR because of La Rochelle TMA at 2000ft, and I continue VFR after Epernon EPR VOR to avoid Paris TMA.
Why do you want to do that? Non-deiced and 0deg just above 3000ft?
We don’t know where controlled airspace lies (i.e. we don’t have reliable airspace data), and AFAIK neither does Eurocontrol.
We currently don’t do coordinate waypoints, as this would probably massively hurt computation time.
France has roughly 1300 intersections. If we were to add a coordinate grid with 5 minutes grid distance (to be below 10NM), this would add another 30000 intersections, i.e. roughly multiply the number of intersections by 25.
I would expect the slowdown to be between linear and quadratic, so between 25 and 625. Far too expensive IMO.
I would want to do that
1 flying eastbound: if icing is forecast at FL60 for instance, I shall file at FL50 only if I have a way to descend if needed.
If the MSA for a FL50 routing does not permit me to descent (or if the routing is over a city that is forbidden to overfly below 3300ft, many of them in France) , I have to find a routing which is allowed at 3000AMSL. I will probably not be able to find a routing flyable both at 3000ft AMSL and FL50. So filing at 3000ft is the only way.
2 In case of complicated airspace (around Paris for instance), where the workaround might be to fly below the TMA out of controlled airspace. Try Toussus Le Noble to Charleroi, Autorouter route is via Dieppe.
I don’t think that the calculation would be so complicated.
You would use the same algorithm, and ignore the “SEGMENT TOO SHORT” errors at each step until you find your optimized routing.
Then you just add several waypoints to shorten the segments. The resulting route should be accepted in most cases (I think a great circle issue may cause the resulting route to be rejected in some cases). That’s what I did, using Skydemon and Eurocontrol website, to find my routing from Royan to Toussus.
The added way points would not stay in your database.
Of course the routing must be checked against regulated airspace, MSA etc. That can be done manually
Another feature would be to permit the user to avoid zones. It is now possible to add a mandatory zone to overfly in the vicinity of a specific waypoint, it would be helpful to be permitted to reject a specific zone around a waypoint.
The basic problem with IFR autorouting is that it is meaningful only in the “Eurocontrol IFR” context, which means the flight is mostly or entirely in controlled airspace – as per “classical” IFR everywhere in the world.
Autorouting outside CAS (OCAS) is a completely different idea and it has no real meaning because (please don’t take this the wrong way 
) anybody who has a PPL should know how to spread the map on the floor and draw a line on it which avoids CAS. If not, go back to your PPL school and ask for a refund on the 10k you paid them 
There are many possible routes depending on many factors e.g. normally you fly below cloud for comfort and strategic reasons to do with not getting trapped between lowering cloud and rising terrain (especially if cloud = icing conditions), and more experienced pilots plan routes on IFR waypoints because these are already in all the GPS databases.
Technically, it is possible to autoroute such routes (notwithstanding the huge computational overhead as Tom describes) and there have been tools which do that. For example the old Jeppesen Flitestar/Flitemap products do VFR autorouting (which is the same as IFR OCAS autorouting – for countries which allow IFR OCAS which is most of Europe) and you can tick checkboxes for what to avoid (CAS, military areas, all sorts of stuff which has one meaning in the USA and a completely different one in Europe e.g. danger areas) and it goes away and in a very impressive way it draws thousands of possible tracks and gradually converges (or not, if you put in too many constraints) on a route which contains hundreds of waypoints which are unusable unless the route is loaded directly into a GPS (which has to be a handheld) and flown totally following the magenta line on it…… If I could do a video of a screen section easily I would do one and post it. It’s an impressive but useless function. Flitestar VFR Europe is about €100 but almost nobody uses it AFAIK.
If you want to fly IFR OCAS, the best way is to file a VFR flight plan and just fly it, in IMC or not. To be legal you need an IR (or the IMCR in the UK). Being VFR, Eurocontrol can’t reject it because they don’t see it.
The only issue is if you want to fly an instrument approach (IAP) at the destination. In the UK, you can just ask for an ILS or whatever, at the end of a VFR flight plan. In the rest of Europe, this depends and I have not really tested it. I have done it in a few places (I mean without declaring a Mayday; then they have to let you ) and it always worked.
The problem is that filing an IFR FP at say 3000ft doesn’t entitle you to an IAP. In fact, the national ATC may just throw it away because it isn’t “seriously enough IFR”. In the UK, almost anything below about FL060 (can go lower if wholly in CAS, especially if it’s a training flight) gets thrown out by NATS – even if accepted by Eurocontrol – and the rules for this are confidential.
So there are no good practical solutions to this.
If you want to fly IFR OCAS, the best way is to file a VFR flight plan and just fly it, in IMC or not…
What you suggest may be reasonable in the UK considering the special ATS situation there, but I would advise against it in other countries.
What you suggest may be reasonable in the UK considering the special ATS situation there, but I would advise against it in other countries.
What would you suggest, and why would you advise against it? Can you offer country-specific detail?
An “I” flight plan (actually a “Z” or “Y” too) gets sent to Eurocontrol for validation, and if they don’t pass it (e.g. because it is mostly OCAS, because it is too low) you can’t fly it.
This is how Europe is set up.
In the USA you can file IFR anywhere above 1200ft, I think (the base of Class E, generally) because they don’t have a route validation computer system run by a bunch of unix hackers whose solution to everything is to write another 100,000 lines of code, probably in Fortran (oops I meant C++). You won’t get a radar service, due to terrain, but that isn’t a question anybody asked
De-Gaulle and Orly APP will not accept you below the minimum altitudes for the STARs anyway. And IIRC they are generally FL070. So what you propose does not only pose a technical problem for the autorouter tool, but also practical problems during the flight.
He doesn’t seem to want to fly STARs. He wants to stay OCAS and do his own thing.
An “I” flight plan (actually a “Z” or “Y” too) gets sent to Eurocontrol for validation, and if they don’t pass it (e.g. because it is mostly OCAS, because it is too low) you can’t fly it.
Yes, but they do not care about the VFR part, i.e. you can write anything into the VFR part. They only due some very basic checks, like whether the total enroute time is within a factor of two or so of what they think it should be from the cruising speed and route distance.
But also, you (or the frontend tool, such as autorouter) has to do the flight plan addressing for the VFR part, they only care about the IFR part. But as long as the VFR part of the route is parseable (such as the example from the OP, unlike descriptive stuff like “FARMER JOES HAYSTACK”), that shouldn’t be a problem.
@boscomantico: you are welcome to try, but Orly approach will reject you below the minimum altitude for STARs and I cannot see how you could do an IFR approach into Toussus without talking to Orly APP, and possibly Velizy APP.
I tried to make it into Pontoise like that once due to icing, and that made a helluva balluba.
In the rest of France I think such practices are doable, although not sure about Marseilles/Nice area.
If anyone has experience with flying IFR into the Paris group airports OCAS I sure am very interested in their tales.
