I laughed out loud when I got to this part:

> Intervention: Jumping from an aircraft (airplane or helicopter) with a parachute versus an empty backpack (unblinded).

also: "the trial was only able to enroll participants on small stationary aircraft on the ground, suggesting cautious extrapolation to high altitude jumps." :)

In realty I think a proper trial is supposed to always use the best known treatment as control.