On the difficulty of testing lifesaving treatments, there's a great paper on this topic:
"Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials" [0]
It has some great gems like:
- No randomised controlled trials of parachute use have been undertaken
- The basis for parachute use is purely observational, and its apparent efficacy could potentially be explained by a “healthy cohort” effect
- Individuals who insist that all interventions need to be validated by a randomised controlled trial need to come down to earth with a bump