The issue with respect to shoulder belts has been settled for awhile. The NTSB, FAA, TC, CAA, etc etc all have universally recognized the worth of shoulder belts. Without one even a relatively mild crashes will cause the person to bend around the lap belt slamming their face into the knobs and bolts sticking out of the instrument panel. Use of shoulder belts has greatly reduced head and facial injuries in crashes.
The good news is that you see many examples of very bad accidents with the wings and tail ripped off but the cabin area still basically intact. In addition the usual situation during a crash is that the engine mount will rip away from the firewall and fold under the aircraft or to one side. The ones where it goes into the cabin usually involve hitting the ground at a very steep nose down attitude and are almost invariably fatal.
The bottom line from my POV is any pilot that does not wear fitted shoulder belts is a fool and I will not personally fly an aircraft that is not fitted with shoulder belts .
Last edited by Big Pistons Forever; 11th August 2012 at 23:11.