One way of thinking about it is like crossing a road. Airmanship is like knowing your green cross code. It's what you teach yourself to do every time. You stop, look, and listen and check it's clear. TEM is about thinking about, and adapting to, situations. 'Threat' is thinking that, as you're about to cross a busy dual carriageway, maybe it'd be better managed by walking down the road a bit and using a bridge. 'Error' would be akin to saying, I'm in France and they drive on the other side of the road. By habit I tend to look the wrong way so I'll manage it by always pausing to remind myself to check more carefully.