So, a few possible causes for the say agains:
- See above, multilingual environment
- See above, terrain features
- See above, six digit frequencies
A few suggetions of my own:
- Early morning, you'll get a lot of flights returning north from Africa. The crew will be tired and less alert.
- It is my firm conviction that since the introduction of 6.33 kHz sets, the sound quality of the airborne equipment has deteriorated.
- Many flights transiting through the Geneva FIR are assigned slot times before departure. Not beneficial for alertness.
EuroATC, I think your suggestion to speak more slowly can only help. If only other controllers did the same thing, especially in North America. For they don't realise that English, for many of us, is still a foreign language.