Black Box: Secrets Revealed | 1999
Documentary about the black box, sometimes the only thing to survive an airplane crash intact. A black box must pass long series of tests to make sure it can preserve the information it records under any circumstances. Black boxes are fired from a cannon at 34 Gs, stabbed by 1/4" hardened steel rods, crushed in a vice at 5000lbs pressure, barbecued with blowtorches for one hour at 1100 degrees Centigrade, and finally, submerged for one month under 20,000 feet of seawater. Plane crashes are so rare, each one has its own unique factors and it is the black box that brings those flaws to light.