Vec - I would argue that a commanding officer should have a well informed (via personal experience wherever possible) mindset as to just how "nails" the jobs those under his command do when they put themselves into harm's way. Thus, albeit an engineer might be able to understand that flying and fighting a Typhoon/F3/GR4/9 is quite hard work, he would never actually have that first hand experience to understand what he was asking of his men, whereas an infantry officer will have that understanding, having done (at some point in his career) the platoon cdr's cse and such like.