In reply to The New NickB: We tend to use CTC transparent bag approach. This allows long term parking eg at Stansted, cycle to departures, remove pedals, turn bars and add a bit of padding here and there. Bung in bag and wrap loads of duck tape. At destination, reverse procedure and bin the bag etc. Once opened out, it is hard to squeeze all the air out so it can be a bit too bulky to carry. We usually carry another bag for the return as it is less stressful than trawling shops for materials the day before flying home.
So far ( after about 8 flights each), bikes have arrived in one piece though it was disconcerting to see our bikes underneath about 80 cases on the baggage trolley on the tarmac once.
This year we are flying out to Bratislava and returning from Budapest. It is worth checking where airports are in relation to the city centres and how easy it is to ride out of the door ( super in Copenhagen, Berlin Schonfeld and Tallinn), or use train. Streetview is great for planning ride to or from airports.