For a route to be PSO eligible, it generally needs both airports to be on the territory of the same country. There are a few exceptions but these often involve political anomalies. Example are Stockholm-Mariehamn requested by Finland (Finland + Sweden came close to war in the 1920s over the Aaland Islands), or from Strasbourg to cities all over Europe, presumably because of all the European institutions in Strasbourg.
Loganair are flying Stansted-Dundee because both airports are in the same country (for now at least !), the route is possibly PSO eligible and Govt is prepared to chuck a load of money at the airline.
Donegal-Dublin also meets those criteria
Alas London-Waterford doesn't meet those criteria.
Last edited by davidjohnson6; 23rd Jan 2014 at 22:02.