8 ms·

Black boxes from Jeju Air 2216 stopped recording four minutes before crash

93 points by BostonFern 2y ago

ggm 2y ago
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-737-800-crash-muan-airport-south-korea-90.html#post11805112 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 2y ago
  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 2y ago
    > 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 2y ago
      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.
      - zmgsabst 2y ago
        The struck engine was still spinning — you can see the visual distortion from its thrust reverser being deployed while on the runway.
    - f1shy 2y ago
      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.
      - timewizard 2y ago
        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.
        f1shy 2y ago
        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.
- MadnessASAP 2y ago
  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.
  - timewizard 2y ago
    > 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 2y ago
      > 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.
- f1shy 2y ago
  > 4 minutes is an eternity. private pilot here: 4 minutes is nothing while flying and coping with an emergency! NOTHING!
  - ggm 2y ago
    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.
    - f1shy 2y ago
      Sorry. I misunderstood the context.
marze 2y ago
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.
- Taniwha 2y ago
  remember they turn them off when they're not being used, a 1 hour battery would go flat every day
  - Over2Chars 2y ago
    a nuclear battery would last a few years.
    - f1shy 2y ago
      Hopefully the radiation does not clear the memory…
      - hulitu 2y ago
        We have software for that. /s
    - baby_souffle 2y ago
      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.
  - anshumankmr 2y ago
    Keep recharging the battery on the plane,, switch to battery when there is a loss of power.
  - DoctorOetker 2y ago
    aren't most passenger planes in near continuous use, unless scheduled for repair or sold?
SteveVeilStream 2y ago
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.
- Over2Chars 2y ago
  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?
  - f1shy 2y ago
    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.
  - SteveVeilStream 2y ago
    Battery backup was not required until 2010. This aircraft was manufactured in 2009. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G/part-121/subpart-K/section-121.359 https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...
    - jiggawatts 2y ago
aaron695 2y ago
It was a 2009 plane so didn't have to have battery backup which was 2010 - https://www.pprune.org/11803679-post1676.html https://www.pprune.org/11803679-post1676.html Age - https://www.planespotters.net/airframe/boeing-737-800-hl8088-jeju-air/e54n1v 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 https://www.molit.go.kr/USR/NEWS/m_72/dtl.jsp?id=95090593
et-al 2y ago
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 2y ago
  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.
throwaway290 2y ago
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 https://www.ekn.kr/web/view.php?key=20241228028449548
- kermatt 2y ago
  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 2y ago
    Bleed air contamination one day made one passenger unconscious and a couple days later made crew brain foggy and mistake prone? Seems unlikely
pfannkuchen 2y ago
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 2y ago
  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 2y ago
    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.
DoctorOetker 2y ago
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 2y ago
  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 2y ago
    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 2y ago
      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.
      - DoctorOetker 2y ago
        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).

93 points by BostonFern 2y ago

ggm 2y ago

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-737-800-crash-muan-airport-south-korea-90.html#post11805112 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 2y ago
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 2y ago
  > 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 2y ago
    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.
    - zmgsabst 2y ago
      The struck engine was still spinning — you can see the visual distortion from its thrust reverser being deployed while on the runway.
  - f1shy 2y ago
    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.
    - timewizard 2y ago
      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.
      - f1shy 2y ago
        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.
MadnessASAP 2y ago
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.
- timewizard 2y ago
  > 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 2y ago
    > 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.
f1shy 2y ago
> 4 minutes is an eternity. private pilot here: 4 minutes is nothing while flying and coping with an emergency! NOTHING!
- ggm 2y ago
  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.
  - f1shy 2y ago
    Sorry. I misunderstood the context.

marze 2y ago

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.

Taniwha 2y ago
remember they turn them off when they're not being used, a 1 hour battery would go flat every day
- Over2Chars 2y ago
  a nuclear battery would last a few years.
  - f1shy 2y ago
    Hopefully the radiation does not clear the memory…
    - hulitu 2y ago
      We have software for that. /s
  - baby_souffle 2y ago
    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.
- anshumankmr 2y ago
  Keep recharging the battery on the plane,, switch to battery when there is a loss of power.
- DoctorOetker 2y ago
  aren't most passenger planes in near continuous use, unless scheduled for repair or sold?

SteveVeilStream 2y ago

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.

Over2Chars 2y ago
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?
- f1shy 2y ago
  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.
- SteveVeilStream 2y ago
  Battery backup was not required until 2010. This aircraft was manufactured in 2009. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G/part-121/subpart-K/section-121.359 https://www.ecfr.gov/current/title-14/chapter-I/subchapter-G...
  - jiggawatts 2y ago

aaron695 2y ago

It was a 2009 plane so didn't have to have battery backup which was 2010 - https://www.pprune.org/11803679-post1676.html https://www.pprune.org/11803679-post1676.html Age - https://www.planespotters.net/airframe/boeing-737-800-hl8088-jeju-air/e54n1v 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 https://www.molit.go.kr/USR/NEWS/m_72/dtl.jsp?id=95090593

et-al 2y ago

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 2y ago
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.

throwaway290 2y ago

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 https://www.ekn.kr/web/view.php?key=20241228028449548

kermatt 2y ago
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 2y ago
  Bleed air contamination one day made one passenger unconscious and a couple days later made crew brain foggy and mistake prone? Seems unlikely

pfannkuchen 2y ago

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 2y ago
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 2y ago
  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.

DoctorOetker 2y ago

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 2y ago
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 2y ago
  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 2y ago
    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.
    - DoctorOetker 2y ago
      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).