Comment by Animats
4 hours ago
Here's the one-minute version from the FAA.[1]
Runway overrun areas marked with diagonal stripes have an Engineered Materials Arresting System. There are several different materials used. One is pumice embedded in styrofoam, with a thin concrete layer on top. Large aircraft weigh enough to break through, and the pumice is crushed to powder, absorbing energy. This yields a surprisingly short stopping distance. The aircraft landing gear will be damaged, but the rest of the aircraft is usually intact. The overrun material comes in prebuilt blocks, and after an overrun, only the ones damaged need to be replaced.
It gets a lot of use. The FAA has logged 25 overruns stopped by EMAS, out of 161 runway ends so equipped. That's surprisingly high.
It's a simple, clever system.
That’s pretty cool. I’d assumed there would be something similar to the run-away truck ramps you see on steep grades — basically a deep gravel pit. However, actually thinking about it, something along the lines of a gravel pit would likely cause significant damage to engines (not to mention risks created by engine damage) but also seriously impede emergency services.
Gravel flies. You can't have it anywhere near an airport runway.
(Some planes have no problem with it, though. You can make even the entire runway of gravel if you only fly those.)
That's only a small portion of what the video is about.