I bet this is an issue with an old mainframe used somewhere in the booking system, something that has worked well but is difficult to fix when things go wrong.
I think there is / will be a lot of money to be made trying to solve the problem of software security and reliability. This is obviously an extremely difficult problem, however the number of ancient systems that we currently have interconnected I think more large scale outages like this are inevitable.
edit: As mentioned in [1], I assume that at least someone is aware of the cost-benefit of potential projects; in turn, I assume that someone would've pulled the trigger if the $'s make sense.
I think there is / will be a lot of money to be made trying to solve the problem of software security and reliability. This is obviously an extremely difficult problem, however the number of ancient systems that we currently have interconnected I think more large scale outages like this are inevitable.