Black boxes from Jeju Air 2216 stopped recording four minutes before crash
97 comments
·January 11, 2025SteveVeilStream
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!?
themaninthedark
Did some airplanes have battery backup before that?
It's my recollection of several crashes, where the plane is not immediately recoverable that there is always a concern that the black boxes will overwrite themselves.
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.
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.
throwaway5292
[dead]
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.
kylehotchkiss
I for one would like a few hundred US pesos
brian-armstrong
If a battery is infeasible, perhaps a hand crank could be added for power? In such cases where power was lost, one of the crew could be instructed to provide continuous crank power to the black box.
kylehotchkiss
Yeah; just spin this thing so your surviving family members can know the exact sequence of your demise. That seems maybe a little contrary to survival instinct. Isn’t the first rule of aviation to fly the plane first; last; and always? If you have the ram air generator lowered and the airspeed; you have controls to glide (see gimly glider)
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.
DoctorOetker
aren't most passenger planes in near continuous use, unless scheduled for repair or sold?
magic_smoke_ee
Define "continuous use". The ones used daily sit around about half the time in major airports' temporary parking areas away from the ramp.
Over2Chars
a nuclear battery would last a few years.
baby_souffle
And finding the black boxes at a horrific crash would be easier. Just go in the direction that your Geiger counter makes the most clicks.
f1shy
Hopefully the radiation does not clear the memory…
skirge
battery can explode and you have two problems
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
kermatt
Google Translate suggests: "A Jeju Air passenger plane made an emergency landing at a nearby airport after a patient was found to be in critical condition during the flight."
throwaway290
Bleed air contamination one day made one passenger unconscious and a couple days later made crew brain foggy and mistake prone? Seems unlikely
DoctorOetker
If there was a loss of power, would'nt the passenger cabin have gone dark?
If that is really the case, I would have expected the passengers to have collectively sent text messages informing friends or relatives that "omg, loud noise, lights went off!".
4 minutes would be plenty of time to send messages.
We would have read this information much sooner after the crash, ergo I don't believe there was a power loss.
I fear the data was deleted by some party.
brokenodo
It’s a fair question and I find your comment to be an interesting example of resorting to a conspiracy theory because you don’t understand something that’s easily explainable.
The Boeing 737-800 has batteries that power certain things in the event of a dual engine failure, including cabin lighting.
Those same batteries, on 737s manufactured more than about 15 years ago, do not provide backup power to the flight data recorder or cockpit voice recorder.
DoctorOetker
That seems totally backwards.
In the event of power loss, the data and voice recorded have lower priority than cabin lighting?!
And the cherry on top is that this was the case on 737's until ~ 2010?!
Defusing my bullsh!t alarm with a second layer of bullsh.t?
I would swallow it all ad fundum if you can provide HN with reliable links to manuals, procedures, ... describing how electrical energy for the passenger cabin is prioritized over the data and voice flight recorders!
wlonkly
I don't know if that's correct or not, but if I were to prioritize, I'd put safe passenger evacuation ahead of the recorders.
ekimekim
I'm no expert, but I wouldn't be surprised if it's much, MUCH easier to get "non-critical" systems hooked up to new, better equipment as it would undergo far less checks and approvals.
null
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.
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.
fsh
In the case of MH370, this was most likely intentional, not due to a system failure. Hard to defend against a pilot with a death wish.
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
pfannkuchen
Can we believe the SK government here? If the popular theories about what happened turn out to be correct (e.g. panic, wrong engine turned off), the black box contents would produce an incredible loss of face for SK. Convenient for it to have failed as well.
sushid
Did you read the article? The South Koreans couldn't decipher the content due to the extent of the damage and sent the black box over to the US. Do you think they colluded? Please take off your tinfoil hat on the way out.
pfannkuchen
The contents of the article are irrelevant beyond the fact that SK says the recorder was damaged.
I’m not asserting collusion, but they easily could have sabotaged it before sending it to the US. If the US finds sabotage on the recorder, it becomes a political decision whether to release this information against an ally.
This is well within the realm of realpolitik international political brinksmanship, no tin foil hat required.
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.