I think I may have finally found the common denominator of all forms of aviation.

Recently I was at a gliding airfield which was having an evening 'fly-in' from the local microlight club. Most of the microlight pilots were having sailplane flights and most of the sailplane pilots were having microlight flights. There were, however, a few sailplane pilots looking at the microlights and muttering things like 'You won't get me up in one of those b----y things.' There were also a few microlight pilots standing around looking at the sailplanes saying things like 'You won't get me up in one of those b----y things.'

Now doesn't that sound familiar?