In the wake of GermanWings' terrible incident of flight 9525, I have noticed that the crash location is quite far from the shortest route connecting the two airports.
I then went on FlightRadar24's website and checked that this is the normal route for this flight (and that there is an alternate one that reaches equally far on the other side):
Other companies that fly the same route (Vueling 1894, Airberlin 8947) follow the same flight paths.
Why is this? What limitations are in place that prevent these aircraft from flying over Lyon (and "nearby" region)?