I was wondering, what a black box actually does ? Does it store the in flight data, in case an accident should occur or it's sending it to an offsite backup while in flight ? And if it stores the data, how huge is it's size, cause I've heard airplanes are known to generate several terabytes of data during a flight.

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    $\begingroup$ Possible duplicate: aviation.stackexchange.com/q/1147/8730 $\endgroup$
    – TomMcW
    Apr 8 '18 at 23:38
  • $\begingroup$ TERRAbytes of data in a flight??? Not unless you had a huge number of high-def video cameras all running continuously. FDR’s capture a lot of data, but it isn’t near a terrabyte. They can capture & store all the flights over a week or two, which is downloaded at regular intervals by maintenance. And we aren’t talking server racks of hard drives here! $\endgroup$
    – Ralph J
    Apr 8 '18 at 23:56
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    $\begingroup$ @RalphJ Well, some planes are generating 1/2 a terabyte on each flight, so at least he's in the right ballpark. Take a look at the linked question/answer if you are curious. $\endgroup$
    – Lnafziger
    Apr 9 '18 at 0:05
  • $\begingroup$ @DanielKiracofe That is 10K per second, so well under 1 megabyte per minute. The trans-Pac flight of 12 hours is 720 minutes. So well below half a GIGAbyte per flight, i.e. 200 orders of magnitude less than a TERAbyte. $\endgroup$
    – Ralph J
    Apr 9 '18 at 5:05
  • $\begingroup$ @Lnafziger Looked at the linked article. While the IOT on a 787 might be generating that much data (the article was way short on specifics), nothing suggests that it is all going into the FDR. For example, data on who used which IFE channels & for how long is interesting, and exactly the sort of stuff the IOT can generate in great volume, but that wouldn’t be going into the FDR. I wouldn’t put too much stock in that 1 value mentioned without explanation in the 1 article. $\endgroup$
    – Ralph J
    Apr 9 '18 at 5:13