Korean airline emergency landing goes wrong and many killed

ThomasP said:

IIRC The black boxes have their own independent power supply (ie onboard batteries whose sole purpose are to power the recording devices and the location transponders), but if the devices that send the information to the black boxes stopped sending at 4 minutes before the crash then saying that the black boxes stopped recording might be an imprecise way of saying what happened - ie the sending devices stopped sending so there was no incoming data for the black boxes to record. Maybe?

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Thomas, I agree that it is possible that the Boxes stopped receiving data, so they had nothing to record, that is probably what happened now that I think more about it.

But in my experience (and granted the last time I worked on a Boeing Product was in 2006, so almost 20 years ago now) the batteries on the black boxes did not power the boxes themselves, they only powered the underwater locating beacons. But as already stated we will have to wait for the authorities to eventually find out what happened, and then inform us.

Actually, I just had a thought (yeah, yeah, I know ) - when was the Jeju 737 built? IIRC the requirement for independent and/or onboard power supply did not take effect until around 2011(?). I do not know if retrofit was/is a requirement, so If it was built before then it may not have the independent and/or onboard power supply set-up.

I do not mean to harp on the subject, or cause undue speculation, but the first thought I had when I read about the recorders stopping 4 min before the crash was that the only way that is supposed to be able to happen (with the independent and/or onboard power supply system) is via kinetic energy effect - either from blast, mechanical penetration from foreign objects, being crushed, or extreme high-G impacts, with failure due to the last two causes extremely unlikely due to the design.