But you need to check terrain clearance even for flight plans only using airways, IFPS doesn't do that either! For example, you can file the following flight plan: -(FPL-ABCDE-ZG -1P28R/L -SDFGLOR/S -LSPV1500 -N0137VFR BARIG/N0137F080 IFR J50 WIL W110 LEPLA/N0135F020 W102 BALIR W102 DELMO W102 LPS -LSGC0044 -RMK/IFPSRA PBN/B2) It's a good flight plan - for a tunnel drill :)
I am too lazy to plot that route but isn't this a case of IFPS always allowing FPs with very low levels in them e.g. FL020?
No airway MEA should be below the terrain. IFPS used to enforce airway MEAs years ago (so the only way to file an airway route at say 2000ft was by fooling it by using waypoints like MID000000) but nowadays it doesn't seem to do that.
I don't know any country where you can drop out of controlled airspace when flying at least 2000ft above ground level
Most of the UK will do nicely 
No, but filing on the airway gives a very high probability you will trigger the RAD that forbids it if they don't want you there
I think one will always be vulnerable in that respect. Either the airspace owner forgets to tell IFPS, or the mil activity was unplanned until after you got airborne. The latter in particular can never be guarded against, which is why we have the ambiguity of the "implicit whole route IFR clearance" which the whole IFR world assumes (it has to) but which is really valid only in the lost comms scenario.
IFPS does enforce airway MEA (at least unless there's a bug, and apparently a few weeks ago there was one), the W102 case is exploiting a deficiency in the implementation. W102 MEA is defined as 2000' AGL, yet the IFPS router does not have an elevation model, so it substitutes 2000' AMSL. It also does not handle the austrian peculiarity of having 2 MEAs (one AMSL and one AGL), AFAIK formats like AIXM don't allow more than one airway base level.
Ok, UK is special, of course, it always is 8-) You have some peculiar ideas, especially for IFR 8-) But I can't complain, LARS and USAF service was pretty good.
Tom - reading your PDF, what does the schematic "Figure 26: MS5534 Interface" do?
This is the interface I use to convert the RS232 of my stone age panel mount GPS to USB for connection to my tablet PC. It also contains an MS5534 pressure sensor I can use as backup altimeter should all 4 static port altimetry sources fail. It works surprisingly well, at FL100 it reads about 60ft too high.
And I can switch display to metric :) Although last time in the Ukraine, they gave me clearances in ft and no PAR approach, what happened to ex Soviet aviation?
