Similarly: I worked on some avionics networking software a few years back, written in C, and a surprisingly old version of GCC (I think from the late 1990's, in

Similarly: I worked on some avionics networking software a few years back, written in C, and a surprisingly old version of GCC (I think from the late 1990's, in 2006-2007, so approximately a decade old then) was being used. That particular version had already been qualified for avionics development at the company, and to upgrade to a newer version would have meant assuming the cost of requalification. Just so long as the old compiler worked well enough, they had no reason to upgrade. (I did uncover a bug in the compiler which I had to work around, but wasn't enough to warrant an upgrade.)