Chaps,
Surprised no one mentioned this so far, the basics of any survival are:
Protection
Location
Water
Food
So much of what you take depends on what you are doing, where, when, how much space in helicopter have you got, who's side you are on etc. Always pack for that unscheduled landing.
In another life I remember being distinctly happier with 20 heavily armed soldiers down the back, that covered the first two quite nicely. Nowadays don't think you can go too far wrong with a company credit card and a mobile phone.
