What happens if you jump from a plane with an empty backpack?
Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial
15 years later someone actually ran the trial. Parachutes made no difference. (The plane was parked.)
Volunteers were randomly given either a parachute or an empty backpack, then jumped out of an aircraft. Nobody in either group died or got hurt.
The catch: the aircraft was on the ground, so the jump was about 60 cm. The paper is a brilliant warning about trials whose results don’t apply to real-world situations.
Always read the methods section.