STEM与日常科技·英语30篇（2）
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Why Airplane Black Boxes Survive Crashes
飞机黑匣子为什么耐摔
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Black boxes — actually bright orange for visibility — contain two separate recorders: one for cockpit voice and another for flight data.
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Each unit is wrapped in a 1-inch-thick aluminum shell, then layered with heat-resistant insulation and a stainless-steel outer casing.
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They must survive impacts up to 3,400 times Earth’s gravity, equivalent to hitting concrete at over 300 mph.
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Temperatures inside the recorder must stay below 270°C during a fire lasting one hour at 1,100°C.
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Underwater locator beacons automatically activate upon contact with water, pinging at 37.5 kHz for up to 30 days.
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Crash tests include dropping units onto steel plates, crushing them with hydraulic presses, and submerging them in saltwater tanks.
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Manufacturers embed memory chips in shock-absorbing gel to prevent vibration damage during turbulence or hard landings.
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Despite their name, black boxes are never black — their color and reflective tape help search teams find them in wreckage or ocean mud.
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Newer models record more parameters — up to 2,000 — including pilot inputs, engine vibrations, and cabin pressure changes.
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Even after decades underwater, engineers have recovered readable data from recorders using specialized cleaning and signal-recovery tools.