Not sure about all of Boeing. I worked for a subcontractor who got a small piece of the project from Honeywell who contracted with Boeing. But we worked on aircraft from Boeing, Gulfstream, Airbus, etc and other than the 787 Ada stuff (which we ported to C), I don't recall seeing anything that wasn't written in C, C w/ classes (heavily stripped C++), or Javascript. Of course it's possible that my boss just asked for those types of projects since we had the most expertise there.