There’s a scene in Ron Howard’s wonderful film, Apollo 13, when the crew is preparing to fire the LEM engine in space and Commander Lovell is Seen ensuring that his socked feet are firmly attached to the velco floor. That might well be authentic, but it leaves audiences with a mistaken notion of when flying the LEM was like during a landing.
Landings were dangerous because there was a big moon outside, just waiting to smash into you. The LEM had to maneuver, and the crew could be tossed around as it did so, just as they needed precision control. If something went wrong (as it did in Apollo 10) such an upset could elevate a minor problem into a crisis, but even under the best of circumstances, landings could be hard, and the last thing you wanted was for a suited astronaut to bang to into a bulkhead, breaking the suit or the LEM.
NASA needed a way to hold the astronauts down so they could focus on their jobs while giving them the mobility needed to move about the cabin as needed. It had to be light, it had to be reliable, and it had to be dead simple. Their solution? The Apollo LEM Crew Restraint System: