While working at NASA on code related to the Space Shuttle I once found a piece of Fortran that jumped into assembler. The assembler bit used a parameter to decide where to re-enter the Fortran code. Over time every exit but one was commented out. I asked "Can we just patch the software to jump from here to there instead?" and the answer was "Your six month project is to replace Fortran with 'C' and that's about how long it'll take to get a code change through the committee." People take flight safety very seriously.