There is no such thing as an "indestructible" case. Flying with an instrument is ALWAYS a risk of damage or theft! I've seen it all in 20 years of international music travel. Every style case can fail & all are subject to airline personnel working at minimum wage.
The SKB i-series are really great, but i have seen them break & leak afterwards.
Anvil style cases are wonderful, too, but so heavy (can you say oversize & overweight fees?) and also are prone to damage. I've seen a forklift go right through one!
It comes down to what your acceptable risk to cost ratio is. A private insured courier being the safest and most expensive option (Rockit Cargo, for instance) down to wishing the best with a flimsy gig bag. Oddly enough, the gig bag will make it safely 9 times out of 10 (but who wants to be the 1 out of 10?).
I've traveled extensively across the globe for 2 decades: everywhere from Turkey to Argentina to Scotland to north NORTH Canada. I have had very few instruments damaged. Only twice that I recall.
I have had good experience with the SKB Bass Safe boot & their standard plastic hard shells. Reasonable protection, mimimal (if any) oversize fees and what has been an admirable track record in my experience.
That said, I do not fly with my '75 Ric. It's just too precious to me (the tone is exceptional for some reason ?) & not worth the risk. With any case or carrier.