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.
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.
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.
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.
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.
"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.
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
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.
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.
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.
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.
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.
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?
> 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.
Data about recovery efforts after system failures is also valuable. It can help improve procedures for similar future events.
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.
Even that is valuable information for discerning what went wrong and how.
private pilot here: 4 minutes is nothing while flying and coping with an emergency! NOTHING!
The antiquated technology in jets is mind boggling.
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.
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?
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!?
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.
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.
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).
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.
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.
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?
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
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.
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.
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.
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!