As someone who is currently consulting on an airline industry project, you are absolutely correct in identifying how terrible the internal legacy systems are. Everything is built on SABRE, which was first created in 1960 and absolutely shows its age. If SABRE was a person, it could retire.

What's worse though is that inside the industry there's little awareness of the possibility of doing things differently. Everything is just layers of wrapping around the old system without any abstraction of the processes.