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.

[1] https://www.youtube.com/watch?v=hVSvU06_NGE

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mrexroad 10 hours ago | parent | next [-]

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.

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Animats 8 hours ago | parent | next [-]

These overrun areas aren't that long. This trick is used where there's not enough room for a long overrun area. The high drag has to start fast. With the styrofoam/pumice material, the wheels quickly drop all the way to the hard bottom of the arresting material, and then plow forward, dissipating energy by crushing pumice. With something more solid, the wheels may skim the surface for a while before digging in.

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marcosdumay 9 hours ago | parent | prev [-]

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.)

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andkenneth 8 hours ago | parent [-]

the distinction here is mainly jets vs props.

	▲	stackghost 6 hours ago \| parent [-]
		Gravel will happily fuck up a prop just as much as a turbine; it's more about ground clearance. The engines on modern airliners are quite low to the ground, which is why they tend to ingest gravel kicked up by the nose gear.

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hobofan 12 hours ago | parent | prev | next [-]

That's only a small portion of what the video is about.

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kmarc 4 hours ago | parent | prev [-]

Hah, I guess this is the same then as in formula 1 (and possibly other motorsports). After the end of a straight (speeding) section, just before the curve they have 150/100/50 (m?) distance indicators. Sans the concrete block at the top. That would obviously shave the driver's head off.

When a driver hits these, they evaporate as dust.