Your touring bike won't fit in a hard shell case, and if it did, it leaves you with the difficulty of where to store the case when you get there.

Phone the airline and see what their requirements are.
Some want the bike boxed (you can get these from your LBS as they are the boxes the bikes come in) some don't. if they don't I have in the past made sleeves of bubble wrap to go over the vulnerable areas, but pipe insulation would also work.

Take the derailleur off and tie it up so that it doesn't get pushed through the wheel if handled badly.

Slightly deflate tyres (though I think all holds are pressurised now)

I have carriedbikes on planes many times and have had a couple of problems, but luckily always on the return journey.