Similar point has been raised in the following paper:
http://www.bmj.com/content/327/7429/1459"Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials"
Results: "We were unable to identify any randomised controlled trials of parachute intervention."
We think that everyone might benefit if the most radical protagonists of evidence based medicine organised and participated in a double blind, randomised, placebo controlled, crossover trial of the parachute.
http://www.bmj.com/content/327/7429/1459 "Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials"
Results: "We were unable to identify any randomised controlled trials of parachute intervention."