Pretty much unavoidable when it comes to real time embedded systems. Your options in that world are pretty limited, especially on space-rated processors which are generally many generations old, and can't necessarily handle huge performance overheads.
This is probably because Ada was mandated for government projects. The people buying compilers were most likely able to charge that expense to the government, possibly even with a mark-up.
The language had a weird temporary resurgence a few years back. It seems to have started by the free Ada compilers becoming decent and by people starting to get serious about security holes. It seems to have ended due to rust claiming that niche.
