Re: God, the stress involved in writing this stuff...
There is more certifiable code written in C than Ada, with C++ on the way up. The challenge is in proving that the executable is correctly implementing the safety requirements, not what language is used for the source code. Software to help with the traceability of requirements to source code to executable code tends to be (there are relatively few examples) written for C first, then C++ and rarely for Ada (I'm told there is some, but I've not seen it).