I wrote "This tends to happen in Germany and nearby." It happens in the lower airways too.
It doesn't usually matter, but if say going east and at FL180 and only just skimming the tops, and they offer you the option of FL170 or 190, and your absolute ceiling is FL200 on a nice cold day, it isn't a good choice, and I would refuse.
Anyway, Rob's question is a curious one!
I wrote "This tends to happen in Germany and nearby." It happens in the lower airways too.
If you said "it happens nearby Germany" it might be correct because it definitely does not happen in Germany. As long as the flight level ends with a zero, ATC will be happy. There are absolutely no semicircular levels for IFR in the lower airways in Germany. If they refuse a certain level, it will be because of traffic or airspaces, not because of semicircular levels.
BTW: In Germany, the semicircular levels are not even relevant for VFR, neither are the the 500ft levels. Officially you are supposed to obey them when VFR but in reality ATC/FIS wouldn't care. I would estimate more than 50% of all pilots I hear on FIS to not care (including myself) and I have never heard any ATC or FIS unit remind the pilot of VFR or semicircular levels.
It doesn't usually matter, but if say going east and at FL180 and only just skimming the tops, and they offer you the option of FL170 or 190, and your absolute ceiling is FL200 on a nice cold day, it isn't a good choice, and I would refuse.
Rob, just to clarify the above statement: Eurocontrol routes are notified as a whole for certain levels. So going in one direction you may have to fly at FL140, FL160, FL180 and so forth, while flying the other direction you may have to fly at FL150, FL170, FL190 and so forth. Obviously there are also minimum and maximum levels (sometimes for the whole route, sometimes per sector) depending on terrain and airspace layout. But the level/direction combination remains the same throughout the route.
So even if a route meanders around one of the cardinal or semi-circular compass points that would normally cause you to change levels when flying VFR or uncontrolled IFR, the level on a Eurocontrol IFR route stays the same.
It would be silly otherwise. For example, consider the following scenario. An IFR route A - B - C where A -> B is heading 005 and B -> C is heading 355. Aircraft northbound would fly, say FL100 from A -> B and FL110 from B -> C. While at the same time aircraft doing C -> B would be flying at FL100 and B -> A at FL110. What would happen at B? You'd better have somebody standing by on the ground with a broom to sweep up the pieces.
All IFR Eurocontrol routes are listed in the countries AIP (ENR 3 section). They include possible directions (some are one-way), minimum and maximum levels, and the levels that are available for each direction. You will also find that cross-border routes are coordinated internationally so the intersection at the FIR boundary will form a seamless connection between the legs - although to get the description of the whole route will require you to consult AIPs of different countries.
It is. That's why tools exist to help you. EuroFPL is one, but there are plenty others.
EuroFPL will take your proposed route, will run it through the Eurocontrol validation 'puter and will tell you if the route is acceptable or not. Even considering your take-off time, since routes are not always available 24/7. EuroFPL will also propose its own route, will forward a route proposed by Eurocontrol, and will consult its database of routes that were proposed (and validated) previously.
So in practice there is virtually no need to dig out the AIP, IFR en-route charts and such to come up with a sensible and validated route.
God this has got complicated, I will leave it. Rob
:-) Just file your flight plan and put in a flight level that matches your general direction from start to destination. Odd for eastbound and even for westbound. Then, under item 18, write: RMK/IFPS REROUTING AND LEVEL CHANGE ACCEPTED and you shall be fine. This is the way our dispatcher does it with every flightplan he files for us and so far there have been no complaints. In the lower airspace nobody seems to care much anyway, it is rather the upper airspace and especially the most sought after levels between 320 and 380 (the upper limit for most airliners) where the semicircular rules really matter.
I use EuroFPL for filing flight plans, but EuroFPL doesn't offer a "routing generator". They only have access to the Eurocontrol "route suggest" facility.
The only route generators currently out are FPP, then Rocketroute (which runs same code as FPP), and maybe some others I vaguely recall hearing about.
FPP is dead easy to use. Just download the (windows or Mac) app, install it, and off you go. I use it in a very simple way, without entering any aircraft performance details.
IFR flight planning is pretty simple nowadays.
... and maybe some others I vaguely recall hearing about.
We (like almost anybody who tries to make a living from flying) use PPS. Probably overkill (especially cost-wise) for a single user, but for a group of pilots or a flying club it may be a viable solution. Just knowing someone who knows someone who has access to PPS can help...
There is a lot of them about I am sure.
A German pilot I know, part time bizjet, uses a firm which knocks up a route and some other briefing pack type stuff, for ~€35.
Higher up the food chain you have Jepp which offers various levels, starting at (according to an employee I met at a party 
) some €100/month.
All these date way before tools like FPP came along. In those days, Eurocontrol routings were really a black art. I remember that; 2005-2008. I used an Italian site for sim pilots. Then Autoplan (now dead) came and ended it all.
Credit where credit is due - FPP was out a couple of weeks before Autoplan.
