Hi all - been lurking on and off PPrune for a couple of years, finally taking my first PPL steps (3 hours in the book!). Nice to see a subject that I can comment on without feeling like a complete idiot!
EuroNCAP is a bit of a con actually - cars are made to get the best result at exactly the specified parameters (I've even heard of one that is stronger on the LHS only because the EuroNCAP only crashes LHD cars).
The thing to bear in mind is that cars are designed to give good results at 30 mph and the injuries go up exponentially (with the energy profile). Basically don't expect to have a good outcome at any speed over 60mph that involves a sudden stop. In aviation terms that would be the ground I guess...
Having said that, there is no reason that the interiors of aircraft shouldn't be designed to meet the car requirements - that is a peak decelaration of 80g over no more than 3 m/s (for a 6.8 kg mass travelling at 25 kph) in the head impact zone. The directives are there and all cars currently on sale in Europe meet this. Add in a four point harness (at least) and helmet, survivability goes up considerably for lower speed impacts. Higher speed decelerations will still cause brain injury though.
Best advice is not to crash really - if you really have to, try to scrub off as much velocity as possible before hitting hard things, and when you do, hit head on as the brain doesn't like sideways loads (tears it apart along the middle).
Not a pleasant subject, but very interesting all the same!
JC