I remember reading somewhere that these guys get all the time they want to program these systems, and the environment is very relaxed - I suppose for this very reason.
I left the defence industry eight years ago now, but back then (and based on that job posting below it looks like it's possibly still going on), it was a weird combination of ADA, C++ (sometimes C instead) and Java.
In the late 90s, there was a big push in both the US and the UK defence industries to start using off-the-shelf software more, which meant moving to C++ from ADA.
But you'd sometimes have weird systems of ADA being used for the "safety-critical" stuff, which interfaced via CORBA with C++ code controlling it (as a bigger system), and would then sometimes be exposed to the user again via CORBA in Java UI code! (never saw this (Java) on aircraft thankfully, only ships)
A certain UK system also had code for controlling the HUD in ADA, but the main flight control system in C++, again via CORBA interfaces..
This wasn't always the case - some Solaris stuff on submarines was all C++ (with Sun's compiler), but it was frightening the complexity of it.
No, that's a contract I do not want.