Great topic, just for clarity, the Alpha's flight case is a wonderful case, built by Hiscox and it protects the instrument very well when handled normally. Neil has taken dozens of flights with it when checking it in, and never had a problem. However, the case itself isn't reinforced to prevent damage happening to the case itself due to abuse from airport baggage handlers. So while the case strikes a great balance between portability and protection, it's not as sturdy as the super-heavy flight cases that resist against anything. There's of course also the very remote possibility that the case doesn't protect the instrument due to extremely excessive force. The only real way to be sure about the protection is to buy an additional seat on the plane or to have an impossible to carry, custom metal flight case made.
I only flew twice with my Alpha and I totally try to avoid it now, too much stress having to check it in. On the way over to the US, the case was clearly handled extremely roughly and was damaged at several places, the Alpha was fine though. Several SFO airport people made remarks, thinking it contained an air gun. So, on the way back I literally covered the case with self-made stickers saying "!!! fragile !!!' and 'Unique and rare musical instrument'. The case was clearly handled much more carefully on my way back. So I think that alerting baggage handlers like this could be a solution. Sadly thought that doesn't seem to be helpful, as Dave Carroll's "United Breaks Guitars" testifies: http://www.youtube.com/watch?v=5YGc4zOqozo
Hope this helps,
Geert