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.
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?
Battery backup was not required until 2010. This aircraft was manufactured in 2009. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...
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!?
Because adding a battery backup means one (or two!) more batteries that have to be tested and certified to fly; more batteries that have to be checked before flight; more points of failure that could ground an aircraft or cause incidents themselves; more weight on board (especially relevant for smaller craft); etc. etc.
The battery issue isn’t idle speculation; a recent flight I was scheduled for was cancelled when the airline accidentally allowed a battery to deep discharge, necessitating a new battery to be flown in from another city (delaying the flight so badly it was cancelled instead and passengers delayed to the next day).
Fascinating. How did you find out?
They announced the details at the gate. They even told us they were trying to get a new battery in from Cleveland (we were in Pittsburgh). I didn’t find out which battery was discharged though.
I hope that’s a trend. My experience has always been that they give zero information about such circumstances.
> Battery backup being introduced in 2010 as a requirement is absolutely insane
I welcome the formation of your company selling already-certified batteries that will not damage anything around them (like the precious recorded data) if they go from 500 to 0 in no seconds flat, are subjected to pressures of a few kilometers of water, or to a post-crash fire.
The batteries do not have to be located close to the recorded data
Then wires break or get burned. Causing cuts like now.
I find it just as crazy that many or most personal cars come equipped with cameras and sensors all over, but are not required to record any of it for analysis of a collision and attribution of fault.
The most unqualified person can be driving a 10,000 pound (4,500kg) electric Hummer and have no measures in place to use the built in cameras and sensors to determine what went wrong in the event of a collision.
Hell, there are cameras inside the vehicle that can tell us whether or not a driver was using their phone when a crash happens, but it does not seem politically popular to enforce reviewing this footage, even though being in a personal car is far more dangerous than being a passenger on a plane.
The car situation is at the unholy nexus of bad behavior, money, and privacy. My insurance company would dearly love to have access to the existing telemetry in my vehicle. As an alternative, they continually beg me to install a telemetry device in the OBD port in exchange for lower premiums. But their incentive is so obviously to use the data against me in the event of a claim ("ohho! 31 in a 30 zone! Denied!") that I see no reason to do so.
Dashcams, by contrast, provide the operator with reasonable evidence of other drivers' behavior, and consequently are popular - people pay out of pocket to install them.
I suspect that if laws were passed requiring use of telemetry and dashcams all over, all that would really happen is that rates would rise to reflect new data on how badly most of us drive, and claim denials would skyrocket.
It may be relevant that the dash cam is owned by the driver and not the insurance company, and can be selectively used to prove others' fault, but ahem forgotten about if it shows otherwise.
be certain it does at the moment of claim denial. parallel construction for the win
> As an alternative, they continually beg me to install a telemetry device in the OBD port in exchange for lower premiums. But their incentive is so obviously to use the data against me in the event of a claim ("ohho! 31 in a 30 zone! Denied!") that I see no reason to do so.
So your incentive is to pay less money, and their incentive is to pay less money. They figured out a way to do that and still be in business. Obviously, some people might value driving over the speed limit more than the lower premium.
> I suspect that if laws were passed requiring use of telemetry and dashcams all over, all that would really happen is that rates would rise to reflect new data on how badly most of us drive, and claim denials would skyrocket.
You don’t think people would change their behavior if their actions were likelier to result in consequences to their bank account and/or prison time?
Almost everyone is distracted driving to the point that personal motor vehicles are, by far, the leading morbidity and mortality risk for people, especially children.
We go scorched earth when kids are kidnapped or otherwise at risk, but for personal cars, we explicitly look the other way when we have a way to make kids safer.
Quite the double standard people have when they want to break the rules themselves.
This is not strictly true and most cars have black box modules which record control inputs and IMU data.
I have never heard of this used to determine who is at fault in a collision. Does that happen? Also, video would be a tremendous help for ascribing proper blame, so why wouldn’t that be required?
When airbags came out, video recording was expensive, but that has long not been the case.
It does happen! These devices are generally only installed post-2005ish cars and the data is used more for safety investigations (did this car have a hardware fault) than insurance, simply because it takes a decent amount of skill to construct a narrative off those devices.
Video isn't required because even these black boxes, AFAIK, are STILL not required in the US. They also introduce unacceptable privacy compromises for Americans, seeing as how most people subconsciously treat their car as an extension of their living room.
>Video isn't required because even these black boxes, AFAIK, are STILL not required in the US. They also introduce unacceptable privacy compromises for Americans, seeing as how most people subconsciously treat their car as an extension of their living room.
…that is my point. For the most dangerous activity people in the country do, we avoid laws that would help ascribe blame because everyone wants to be able to break the rules. A pilot gets recorded, regardless of their privacy, because they are responsible for other people’s lives.
Why not drivers? They certainly cause damage to other people. And at a rate far higher than a person doing ANY other activity. It’s not about privacy, it is about wanting to avoid accountability.
The airbag module does record acceleration, seat belt status and the general scenario used to deploy the airbags/tighten the seat belts.
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.
There's a slew of models and different methods for recording.
The time period they record tends to be very short, but that does raise an interesting question, when do they stop recording?
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.
Even if the FDR is powered, if the flight computers/systems are without power there is nothing to record.
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?
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.
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.
You would think that such a complicated machine would have some better method to notify pilot which engine failed, instead of "does it smell like right or left engine".
There are a series of gauges associated with each engine, but in a high workload situation it might take some effort to make sense of them.
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It could also be a flock of birds damaging all the engines.
Does the APU automatically start or is it a manual process?
Manual process.
Batteries are there for at least 30 minutes
Not required for planes manufactured before 2010. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...
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.
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.
I for one would like a few hundred US pesos
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.
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)
remember they turn them off when they're not being used, a 1 hour battery would go flat every day
Keep recharging the battery on the plane,, switch to battery when there is a loss of power.
aren't most passenger planes in near continuous use, unless scheduled for repair or sold?
Define "continuous use". The ones used daily sit around about half the time in major airports' temporary parking areas away from the ramp.
a nuclear battery would last a few years.
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.
Hopefully the radiation does not clear the memory…
We have software for that. /s
battery can explode and you have two problems
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
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."
Bleed air contamination one day made one passenger unconscious and a couple days later made crew brain foggy and mistake prone? Seems unlikely
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.
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.
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!
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.
if the parent poster was talking about merely emergency lights being battery powered, and hence main passenger cabin lighting turning off a full 4 minutes before the crash, we go back in a circle and have to explain the apparent absence of passengers texting friends and family about a scary power loss during descent (people would quickly try to figure out if power sockets for their consumer electronics were no longer providing power either and learn from each other that it is the case).
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.
"This is your Captain speaking, we may only have a few minutes to restore power, I am hereby commandeering all your USB cables, we daisy chain them from the passenger cabin to the cockpit" ... ?
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.
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.
> 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.
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.
The struck engine was still spinning — you can see the visual distortion from its thrust reverser being deployed while on the runway.
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.
It's just a button press. US Airways 1549 had the captain starting the APU within seconds after their birdstrike. Your biggest concern after starting is likely exhaust temperature.
Exactly! And he was called out because he did that without following the stablished procedures!
Also is not instant, will take a minute or two. The APU is a turbine that takes time to start. Maybe they did turn in on, but 2 minutes too late. We don’t know.
He was a super pilot, who had extreme good understanding of all systems in the plane, and many ours on that plane. You cannot expect that (and do both want that!) from an average pilot. It seems right now that this very accident may have been caused by not following the procedures.
If by "called out" you imply criticised, then that is not correct. Instead, the NTSB final accident report (https://www.ntsb.gov/investigations/accidentreports/reports/..., p. section 2.3.1) praises the specific quick action:
"Although the flight crew was only able to complete about one-third of the Engine Dual Failure checklist, immediately after the bird strike, the captain did accomplish one critical item that the flight crew did not reach in the checklist: starting the APU. Starting the APU early in the accident sequence proved to be critical because it improved the outcome of the ditching by ensuring that electrical power was available to the airplane. Further, if the captain had not started the APU, the airplane would not have remained in normal law mode. This critical step would not have been completed if the flight crew had simply followed the order of the items in the checklist.
The NTSB concludes that, despite being unable to complete the Engine Dual Failure checklist, the captain started the APU, which improved the outcome of the ditching by ensuring that a primary source of electrical power was available to the airplane and that the airplane remained in normal law and maintained the flight envelope protections, one of which protects against a stall."
The final report also gave a new safety recommendation (A-10-66, p. 124) to develop more appropriate (shorter) checklist for dual-engine failure specifically for low-altitude incidents.
Sorry I wanted to mean “it was pointed out”. I’m not sure of the connotation of “call out”
Thanks for citing the report, which I was too lazy to do. That is my point, as I was replying to “it is just one button” comment. If you do the procedures in the right order, it could be they didn’t have the time to start the APU
Or they started the APU, but never got around to connecting its generator to the main bus. That's a second button press, after confirming it has successfully started.
Wasn't the main issue here that the airport authority had put an obstacle in an area that was supposed to be an obstacle-free zone?
> 4 minutes is an eternity.
private pilot here: 4 minutes is nothing while flying and coping with an emergency! NOTHING!
Yes. My comment was to the amount of data loss. I'm not a pilot and I respect pilots. What a terrible situation to be in.
Sorry. I misunderstood the context.
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.
> 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.
> 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.
> 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.
> is a nice thing to know but [not] relevant for flight safety [edited to what I think you meant]
If the pilots made mistakes you want to know what mistakes they made so you can make changes to prevent future pilots from making the same mistakes. The voice recorder is extremely important to understand what mistakes (if any) were made. Even if they did everything correctly, reducing uncertainty is also important.
> The point of the investigation is to determine what went wrong before the crash became a certainty.
Data about recovery efforts after system failures is also valuable. It can help improve procedures for similar future events.
> The point of the investigation is to determine what went wrong before the crash became a certainty.
That's the reason for starting the investigation. It is not the exclusive goal for it. Increasing safety for all future flights is a big part of why and how this is done. Bird strikes are inevitable.
> Which for Jeju was the moment they lost both engines.
It seems like you do not require any investigation at all.
> should your commercial air liner lose both engines at 1000' in a descent the outcome will be crash
The outcome will be a descent. You do see that the concern here is related to the fact that this failure happened very close to approach and even given this the pilots managed to successfully navigate it to the runway. With the gear up.
I mean, if you touch down with the gear up, technically, I'll give you, that's a crash. If the gear was down it would look very much like a regular _landing_. What precisely went wrong considering the gear _had_ been down previously? So.. it's not hard to imagine how a working CVR and FDR here would help us answer that very question.
Although, your investigation may have been this thorough, do you have the answer?
The biggest question for me, is what happened between the bird strikes and both engines shutting down? Why was the decision made to go around instead of continuing the approach? How quickly did both engines fail?
> managed to successfully navigate it to the runway. With the gear up.
Sadly they did not, well technically yes, they did physically locate the runway, however they were also traveling too high, too fast, and crashed.
> If the gear was down it would look very much like a regular _landing_
It would have still been a very unstable landing half way down the runway with limited braking, no reversers, no spoilers, no flaps. It's very likely they would have still ended up off the end of the runway.
> What precisely went wrong considering the gear _had_ been down previously?
They chose to do a go-around, selected gear up, then with both engines failed the only way to lower the gear is manually, the handles are on the floor aft of the first officers seat. Their would not have been time to access them between when they had lost both engines and were on the ground while also flying the aircraft.
I'm not saying I know what happened, I'm saying that the key to preventing future accidents like this will be in the moments before they lost both engines. After they lost both engines it's clear they aircrew tried to very quickly turn the plane around and land the runway, I have pretty serious doubts that there was any actions that could've made that a successful landing, and if there was, they'll be found in a simulator not on the FDR of the aircraft that DIDN'T make the successful landing.
Some sources would be beneficial here.
Certainly, for a more authoritative discussion on "manual reversion" on a 737 see here (https://aviation.stackexchange.com/questions/77693/are-737-p...), your favorite search engine can also provide a decent body of technical and anecdotal data.
As far as survivability of suddenly losing all engines at low altitude, I relied on my own knowledge and experience, however I can refer you to Wikipedia (https://en.wikipedia.org/wiki/List_of_airline_flights_that_r...). Specifically https://en.wikipedia.org/wiki/American_Airlines_Flight_1572 and https://en.wikipedia.org/wiki/US_Airways_Flight_1549. Those 2 are just about (IMO) the complete body of cases where there was something to learn from the aircrews actions following the loss of power. That being said, there actions were very specific to their circumstances, would be very difficult to train for, and the pilots survived to provide first hand accounts instead of relying on the CVR.
My guy, it's on you to provide your sources, not on me to look for them with my favourite search engine. Thank you for the concrete links apart from that advice.
My bro, It's not on me to provide anything, it's a message board it's everything here is implicitly freely offered opinion.
However, I did provide a link, I also noted that in addition to that link, should you or anybody else want to know more, searching 737-800 manual reversion does in fact return a variety of useful information.
>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.
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.
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.
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
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.
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.
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.