8
$\begingroup$

After the recent announcement of the recovery of the flight recorders of AirAsia flight were recovered, I was wondering if black boxes deteriorate after a set amount of time.

As of now, nothing of the plane MH370 has been recovered, including either of the flight recorders. In another downed flight in the past, it took over two years for the for the black boxes to be recovered from the ocean, and even then the information in the black boxes were intact.

So do these black boxes ever expire? Or do they always keep the information intact throughout the years?

$\endgroup$
  • $\begingroup$ NAND flash can't last forever and will eventually deteriorate, but I don't know if that's a matter of months or millennia. Certainly being at the bottom of an ocean will shield it from most radiation. $\endgroup$ – raptortech97 Jan 14 '15 at 12:55
  • $\begingroup$ @raptortech97 iirc, in 2015 there was a study that showed that unpowered flash memory reliably stored data for one to two years, depending on ambient temperature. $\endgroup$ – Danila Smirnov Feb 8 '18 at 3:46
  • $\begingroup$ @DanilaSmirnov: I've got a few flash drives that sat around inert for considerably longer than that and later were powered up without any problems, and that's just consumer-grade flash; I'd expect that the top-of-the-line flash used for things like flight recorders would be yet more resilient still. $\endgroup$ – Sean Apr 17 at 21:40
8
$\begingroup$

Everything will expire one day, including our Sun. Flight recorders are no exception.

Older flight recorders used magnetic tapes. They used to work like any other tape recorder. At present, solid-state memory boards are used. These are considered much more reliable than magnetic tapes, because no moving parts are involved like magnetic tapes.

Data from both recorders is stored on stacked memory boards inside the crash-survivable memory unit (CSMU). A CSMU is:

... is collectively the solid-state memory chips and a hardened metal container filled with specially designed heat insulating material. It is this container that provides the survivability, for it is able to withstand massive crushing loads, intense heat, and exceptionally high G forces, all of which is proven by crash survivability testing.

Flight Recorder
Image Source

You can see that the memory boards are inside stainless steel shell, which is designed to withstand the crash. Although there is a limit of writes on solid state memory, after a crash there are no more writes.

When the FDRs/CVRs are recovered from a crash scene, there are various methods to retrieve data, depending on the condition of flight recorders. This process can take weeks or months to complete.


Further reading: How Black Boxes Work

$\endgroup$
5
$\begingroup$

Every aviation accident is different. The aircraft flight data recorder is designed to survive likely scenarios, but successful recovery of the data stored on it is not guaranteed. Wikipedia has a List of unrecovered flight recorders which is related.

There is no predetermined amount of time that a flight data recorder might "keep" its information intact. The data is stored on solid state devices these days, so presumably the information would be recoverable as long as the enclosure remains watertight and the internal temperature does not exceed the physical limits of the components. Neither of those conditions are assured and the information may be lost at any time.

$\endgroup$
  • 1
    $\begingroup$ The one thing that does certainly deteriorate is the battery powering the locator stuff, meaning after a month or so it becomes much harder to find. $\endgroup$ – cpast Jan 13 '15 at 19:27
  • $\begingroup$ Modern solid state storage isn't going to be bothered by water either. You may need to rebuild the interface, though. Even consumer grade SSD's will probably survive submersion, if powered off in time and cleaned before restarting. And you can realistically expect 20+ years of data retention. $\endgroup$ – MSalters Jan 13 '15 at 21:09
  • $\begingroup$ @MSalters: Even seawater? $\endgroup$ – Greg Hewgill Jan 13 '15 at 22:09
  • 1
    $\begingroup$ @GregHewgill: Seawater may or may not be kind to exposed metallic contact pads on the chip, but they can be recreated if you're determined, and the actual silicon that contains the data is pretty resilient. There are metal traces inside the chip that are necessary for its function, but they wouldn't be exposed such that the water can get to them in the first place. $\endgroup$ – Henning Makholm Jan 14 '15 at 0:28
  • $\begingroup$ I expect the chips themselves to be encased in epoxy. This helps them survive crashes; it would be unfortunate if the chips came loose. Even without that, the actual silicon is almost always embedded in some kind of shell, often ceramic. $\endgroup$ – MSalters Jan 14 '15 at 8:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.