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Are airliners shielded from cosmic radiation, what materials can blocked this type of radiation?

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No.

Airliners aren't radiation-shielded. Even high-altitude spy planes like the U-2 and SR-71 weren't shielded.

The problem with shielding is that it's heavy. The goal is to put as much mass as possible between you and the source of whatever type of radiation you're worried about. But engineers go to great lengths to keep aircraft weight down. 1 cm of lead shielding around a 737 would weigh about 13,000 kg, about 20% of its maximum takeoff weight. This amount of lead would block about 50% of gamma radiation and cosmic ray doses.

Now, is this bad?

For passengers, definitely not. Even frequent flyers don't spend enough time at cruising altitude for the increased dose to matter.

Sea level cosmic ray doses are about 0.06 µSv/hr. At 35,000 it's about 6 µSv/hr. So a person who stays on the ground for a year gets a cumulative annual cosmic ray dose of 0.5 mSv. A frequent flyer who spends 100 hours in the air in a year gets a dose of 1 mSv. A twofold increase may sound like a lot, but a chest CT scan is about 7 mSv, and the normal background radiation dose (including cosmic rays as well as other forms of ionizing radiation) is 2-4 mSv.

For pilots, who spend a lot more time in the air, it matters more. A pilot who flies 1,000 hours in a year gets a cosmic ray dose of about 6.5 mSv, about a chest CT scan's worth. Over a few decades this does in fact add up to an observable, but not dramatic, increase in cancer rates.

Still, this increased risk for aircrew has not (yet) economically or politically outweighed the cost of shielding.

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  • $\begingroup$ @TypelA Comparing to CT chest is not high, but from your data, radiation is a hundred times bigger at flight than on sea level. $\endgroup$
    – user0422
    Commented Dec 13, 2022 at 17:03
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    $\begingroup$ @user0422 that's correct (I've seen estimates ranging from 35 to 100x higher "at altitude" depending on what is being measured, where and how). But don't forget that "100 times more than almost nothing is still almost nothing. The ratio isn't important. The total dose and the effects of that dose are. $\endgroup$
    – TypeIA
    Commented Dec 13, 2022 at 17:23
  • $\begingroup$ @TypeIA - Let's also not forget that most people spend almost all of their time at sea level and maybe a small handful of hours a year in a plane $\endgroup$ Commented Dec 14, 2022 at 10:43
  • $\begingroup$ I read that commercial aviation avoids the magnetic North pole, because of the radiation risk. This isn't cosmic rays, but what comes out of the sun during a solar storm. The magnetic poles are "holes" in the protection afforded elsewhere by the Earth's magnetic field. Of course, there's also the fact that magnetic compasses don't work there. $\endgroup$
    – nigel222
    Commented Dec 14, 2022 at 11:25
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No, they are not, and this is not a concern for regular passengers (extreme frequent flyers might want to estimate their exposure, though).

For pilots it is a concern, and at least some companies/jurisdictions will have regular checks and possibly compensation for the exposure that is accumulated during service.

Source: I am very close to a recently retired airline pilot and we went over this exact topic.

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  • $\begingroup$ "possibly compensation for the exposure " Compensate with money? Health must be on first place. $\endgroup$
    – user0422
    Commented Dec 13, 2022 at 14:01
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    $\begingroup$ @user0422 some of the compensation measure involve early retirement to prevent over-exceeding exposure limits (kind of equating it to hard labour), compensation is not necessarily monetary in nature in my understanding. $\endgroup$
    – Federico
    Commented Dec 13, 2022 at 14:18
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This is potentially a concern for airplane electronics, and even more so for spacecraft electronics. Cosmic rays can flip a bit in RAM or cause other problems, which can result in software crashing or doing something different from design. It really doesn't matter if one passenger a day has their in-flight entertainment system crash. But it does matter if the auto-pilot or the engine controls don't work as expected.

There are a number of things done to harden critical systems. One of the most important is redundant systems are used. This helps minimize (nothing can totally eliminate computer problems - that's why we have humans in the loop) computer problems, whether due to cosmic rays, faulty parts, software bugs, loose wires, electrical surges or any other causes from taking the systems offline. The odds of one flight computer having a problem on a particular flight due to a cosmic ray is very, very low. The odds of multiple flight computers on the same flight having similar problems due to cosmic rays is really, really, really low.

In theory the flight computers could be shielded really well to protect from cosmic rays - much as the flight records ("black boxes") are built to withstand a typical crash - but there are plenty of other reasons why computers can fail, so putting the extra weight into redundant computers instead makes a lot of sense.

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    $\begingroup$ In the aerospace world so called radiation hardened electronic components can be used if needed, so this is not really an issue. $\endgroup$
    – sophit
    Commented Dec 14, 2022 at 5:43

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