Not sure if this still applies but years ago, there were Airways and Upper Air ROUTES not airways. This was because below FL245 (now FL195), airways were established what is now called class G airspace, but above 245, all airspace was class A; nowadays all; airspace above 195 is class C with upper air routes running through it.
To put it in its simplest form, in the UK, airways are individual control areas, whereas upper air routes are defined routes through one huge control area.
Last edited by chevvron; 19th May 2011 at 14:01.