Black boxes from Jeju Air 2216 stopped recording four minutes before crash
44 comments
·January 11, 2025SteveVeilStream
f1shy
Note that just shutting down normally the engine would not cause a power loss. Only in the case of a turn off with extinguisher. Of course after bird strike you shut it down with extinguisher.
Now there is clear procedure, with checks that has to be memorized, where you first identify the engine. Pilots are regularly tested for that procesures. Why it went wrong?
asmor
I remember that Boeing changed which pack provides air conditioning to the cockpit between the 737-200 and the 737-300, which lead to a few similar situations in which pilot were confidently wrong which engine was bad based on smell alone.
gorm
It was changed in 737-400. Before it only took air from the right engine, but 737-400 took from both. In the Kegworth air disaster, which was caused by a failed blade and the system causing a fire trying to compensate by injection of more fuel, the pilot assumed the fire was in right engine and turned it off as crew never notified them which engine was burning. When they discovered the error the speed was too low to kickstart the engine.
Over2Chars
I was under the impression that these CDR/FDRs were independently powered. But a quick Quack on DuckDuckGo didn't answer anything.
That two different recorders both went titsup at the same time I find mind boggling and very sus.
edit: apparently they have both AC and a battery backup, if the internet is to be believed.
Which makes a simultaneous loss of two devices with battery backups... curious.
Did they get hit with an EMP?
SteveVeilStream
Battery backup was not required until 2010. This aircraft was manufactured in 2009. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...
jiggawatts
The general populace seems convinced that black box recorders are made of adamantium and can return data even if the plane falls into a black hole.
Meanwhile every time I read about a crash, I'm horrified by how primitive the requirements (and implementation) appear to be.
This reminds me of my favourite method for reviewing software I had never heard of: I check the release notes. If version v17 has "now uses transactions" then that means that the developers were happy to release the first sixteen major versions with data corruption as a feature. (Conversely, if the notes only mention fantastically obscure scenarios being fixed, then the basic issues have been fixed long ago.)
Battery backup being introduced in 2010 as a requirement is absolutely insane. It's not like batteries or battery backup are new technologies! This stuff has been around forever. Why on earth was this not a requirement decades ago!?
f1shy
If the motor was just shutdown, it should still make power off windmilling. If they discharged the extinguishers, then there is no more power. In any case, that should be recorded.
dist-epoch
Even if the FDR is powered, if the flight computers/systems are without power there is nothing to record.
m463
It could also be a flock of birds damaging all the engines.
dzhiurgis
Batteries are there for at least 30 minutes
SteveVeilStream
Not required for planes manufactured before 2010. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...
marze
How much would it cost to create a data recorder with a built-in battery? Like a mini UPS that would power the recorder for one hour, if external power failed.
The antiquated technology in jets is mind boggling.
f1shy
The problem is old, new planes don’t have that problem. The the technology is antiquated because the planes are antiquated, because they are (or were) built with good quality and lasted long.
Appart from that, how much could it cost? Well, the battery maybe a couple hundred US pesos, but the whole test, verification and validation until approval, plus changing all planes? You have to ask Catl Sagan.
Last but not least: I think the key to understanding the accident will still be there (they shut down the wrong engine, for example) if that is the case, even with this little problem, the boxes dis their work… so, no need for new things.
skirge
battery can explode and you have two problems
Taniwha
remember they turn them off when they're not being used, a 1 hour battery would go flat every day
anshumankmr
Keep recharging the battery on the plane,, switch to battery when there is a loss of power.
Over2Chars
a nuclear battery would last a few years.
f1shy
Hopefully the radiation does not clear the memory…
ggm
I didn't know that was possible. Well sure, almost anything is possible but, this begs questions: how often does this happen, and is there a formal check at some granularity outside of crash events, to check if a black box recorder is working? What's the failure rate?
I'm not pushing conspiracy theory, I'm just a bit aghast the mechanism designed to log things for disaster analysis itself can have .. catastrophic failure before an event.
4 minutes is an eternity. This can't be down to buffer behaviour and the event itself surely?
https://www.pprune.org/accidents-close-calls/663324-jeju-737... has discussion. Yes, catastrophic loss of power takes them off-line. Some kind of UPS like capacity seems necessary.
phire
Because "the event" was the bird strike, and 4 minutes before the crash is the right timeframe for that. At least one of the engines was hit, and they appear to have lost AC power.
The crash on the second landing attempt is just a the conscience of the bird strike, not the actual event.
Apparently this aircraft was just old enough that the black boxes weren't required to be hooked up to any of the redundant power buses.
timewizard
> be hooked up to any of the redundant power buses.
There are multiple busses, but you almost always have an option to tie the two busses together, so one generator can drive both sets of loads. You can also add a battery through an inverter to carry loads. You can also turn on the APU and use it's output to drive loads.
They may have had a more severe failure.
phire
Tying buses together is a manual operation. All indications are that the pilots didn't have enough time to get that far in the checklist.
It's also not that important to restore AC power. The standby bus automatically brings the standby instruments online in the event of a failure, and not that hard to restore the majority of instruments by connecting the main DC bus to batteries. The battery has enough power for 30min of flying, or a full hour if you have the dual-battery option.
> They may have had a more severe failure.
While we only have evidence of bird strikes on one engine, the actions of the pilots seem to suggest that they lost both engines. They were rushing to get back to a runway.
f1shy
You do not have time to start the APU. Moving any switch is a procedure with a checklist, at that hight, once you lost both engines… they had no chance.
f1shy
> 4 minutes is an eternity.
private pilot here: 4 minutes is nothing while flying and coping with an emergency! NOTHING!
MadnessASAP
With a complete loss of electrical power there isn't much for the FDR to record other then airspeed, altitude, and attitude from the standby instruments. However that's already available from radar, ADS-B, and in this case, video.
CVR might have some value, but again in most cases you're just getting a bunch of yelling and swearing before the crash.
As far as understanding what went wrong with Jeju 2216, the interesting bits are going to be right up until they lost both engines, after that it's fairly straightforward to put together the chain of events.
phire
> However that's already available from radar, ADS-B
Not in this case. ADS-B was lost at the same time as the flight recorders.
If there was a primary radar in range, they might be able to recover groundspeed and a 2d flight path. But those have been falling out of fashion, and were never that good for things near the ground.
timewizard
> there isn't much for the FDR to record other then airspeed, altitude, and attitude from the standby instruments.
You forgot the _most_ important data. The position of the flight controls set by the crew.
> but again in most cases you're just getting a bunch of yelling and swearing before the crash.
That has not been my experience. You can hear the pilots trying to work the problem until the last minute and hearing how they made decisions is important. You can also hear the engines, the wind noise, cockpit warning horns, and possible sources of pilot interference.
MadnessASAP
> That has not been my experience. You can hear the pilots trying to work the problem until the last minute and hearing how they made decisions is important. You can also hear the engines, the wind noise, cockpit warning horns, and possible sources of pilot interference.
Knowing the pilots were trying to prevent the inevitable crash right up until the end is a nice thing to know but now relevant for flight safety. The point of the investigation is to determine what went wrong before the crash became a certainty. Which for Jeju was the moment they lost both engines.
> You forgot the _most_ important data. The position of the flight controls set by the crew.
While manual flight controls are a thing, without hydraulic assistance they are really only useful if you're trying to maintain straight and level flight while you start backup power. W1ith compounding problems it gives you a little more control of which direction you will be crashing in.
I won't deny that more data in an investigation is always useful, but the cost of ensuring that data is available has to be weighed against the potential value of that data. With this crash the data after the loss of both engines won't have much bearing on preventing the similar incidents in the future.
To put it another way, should your commercial air liner lose both engines at 1000' in a descent the outcome will be crash, the objective is to prevent that scenario.
Dalewyn
>you're just getting a bunch of yelling and swearing before the crash.
Even that is valuable information for discerning what went wrong and how.
throwaway290
Same physical airplane was in the news a couple of days before the crash for declaring an emergency. Probably coincidence? https://www.ekn.kr/web/view.php?key=20241228028449548
aaron695
It was a 2009 plane so didn't have to have battery backup which was 2010 - https://www.pprune.org/11803679-post1676.html
Age - https://www.planespotters.net/airframe/boeing-737-800-hl8088...
Source it stopped recording - https://www.molit.go.kr/USR/NEWS/m_72/dtl.jsp?id=95090593
et-al
It seems like we're in a period of realizing that airplane systems aren't as robust as we've assumed. E.g. MH370's satellite uplink also lost power.
One possible scenario is that they had a bird strike on one engine but then accidently turned the working engine off instead. Full loss of power from both engines could have taken the data recorder offline in an older aircraft like this one. With both engines off, they may have panicked to try to complete a tight turn to return to the airport and to maintain altitude to make it to the runway. It's possible the landing gear was forgotten but also possible that it was intentional (to extend glide.) It's too early to know anything with certainty but I suspect that the investigation will show that a different set of choices would have allowed them to put the plane down safely (for example by continuing with the initial approach.) Even in that case, they may not have been to blame - for example they may have been following a standard procedure that should be revisited.