Chris,
Have you approached Nats about getting their view point on this? There's been a big drive within the company geared around Human Factors and there are quite a few people employed who deal with this very subject.
Maybe they might be able to help or you may get a better understanding how we (nats) are approaching the job in light of HF?
The chap who is (or maybe was) in charge could talk all day about the subject! (Jason, I forget the surname!) I could try better if you haven't already!
Regards
SE