wouldn't the real world command skill tell you not to go in an iced up twin with ****e instruments?
this "real world" attitude really annoys me. ask the families of any dead instructor if they think their relative was in the real world when they bought it.
Spot the PPL...
But to answer your question... the twin doesn't start out iced up, it gets that way during flight, and it is the management of that situation that is likely to be unknown territory for an instructor, but commonplace for the charter guy.
I can't think of many instructors that have died instructing, but if they have, they either suffered a structural failure or did something unwise. I can't think of any training manouever that is inherently dangerous, if you stick to the rules. There is absolutely no need to deviate from the rules, ever, when instructing.
Charter is a different situation, you can find yourself in a tight spot that is not of your own making, and it is how you deal with it that determines whether you survive the experience or not. You may well have to break a rule or two to get out of it, and it is that level of judgement that is rarely necessary for an instructor.
The world of an instructor is exceedingly simple. If the weather is crap, you stay on the ground. The "sensible" minima for instructing are way higher than those required for charter - in the charter world, if the weather is at or above legal minima at your destination and alternate, you would normally expect to depart (and your CP would certainly expect you to). What happens after departure is where the problems lie.
I did both charter and instructing before moving into the airlines, and I would have to say that charter is amongst the most dangerous and unforgiving paid flying that you can do, particularly if you are pressured - or pressure yourself - to break the rules. That pressure is virtually non-existent in instructing.
What is a "charter frame of mind"? Well, it has nothing to do with dicks. In instructing, your aim is to
impart knowledge and skill. In charter, you aim is to
exercise knowledge and skill. The two are quite different.
You probably only get HOW different they are, when you have done both. CPs know, hence their preference for guys with charter experience.
Quick story... back in the day, when I was doing charter, one of the other pilots got a job ferrying some trawler crews around. One of the crews had a (pretty rough) woman amongst them, so my colleague puts her up the front - I guess she smelled nicer than the others. She decided that he wasn't paying enough attention to her endless chatter, so she reached across, stuck her hand in his nether regions and started fondling his wedding tackle. This gave our guy a bit of a surprise - he ballooned about 500 feet before he got it all back together again (fortunately outside controlled airspace). He pleaded with her to stop, but she wasn't having any - she carried on with her "activities" for the entire flight. Of course, the aircraft had no autopilot so he had no choice but to let her continue, whilst completing an NDB/DME to minima.... "charter frame of mind", see? I wonder if any instructor ever had that happen to them...
True story, BTW.