Now for the big question, why did the electricial power go out?

The two black boxes on the Jeju Air jet that crashed and killed 179 people, stopped recording about four minutes before the diaster, according to officials.

Now for the big question, why did the electricial power go out?

Just a guess: Bird strike in both engines, so generators stopped feeding the main bus. Ram Air turbine deploys but only supplied vital flight control; not CVR and FDR...

Incident: United B39M at Chicago on Jan 12th 2025, coyote strike on departure

A United Boeing 737-9 MAX, registration N37507 performing flight UA-1727 from Chicago O'Hare,IL to Phoenix,AZ (USA), was accelerating for takeoff from runway 28R when the aircraft struck a coyote. The aircraft stopped the climb at 6000 feet and returned to Chicago for a safe landing on runway 28R about 40 minutes after departure.

The FAA reported: "AIRCRAFT STRUCK A COYOTE ON DEPARTURE DAMAGING RIGHT NOSE GEAR, CHICAGO, IL.", the aircraft sustained minor damage.

user comment:

Meep meep: Unconfirmed witness reports claim the coyote was carrying a lighted stick of dynamite, and was chasing a roadrunner, who had already crossed the parallel taxiway

Another coyote issue in the Chicago news yesterday, but not transportation related.

Norwood Park Woman Killed By Metra Train

A 69-year-old woman was fatally struck by a Metra train while stopped at a Norwood Park crossing on Saturday.

She drove into the train crossing at Nagle and Avondale avenues near Northwest Highway, according to a Metra spokesperson and the Cook County Medical Examiner’s Office. She was hit by a Metra UP-NW train bound for Harvard around 3:50 p.m. on Saturday, according to Metra.

There were no other passengers in her car and the train crossing gates were down at the time of the incident, Metra said. The investigation is ongoing and Metra police are still collecting security footage and witness statements.

Now for the big question, why did the electricial power go out?

Just a guess: Bird strike in both engines, so generators stopped feeding the main bus. Ram Air turbine deploys but only supplied vital flight control; not CVR and FDR...

Except...

The Boeing 737-NG such as this one have no RAT to deploy!...

(They rely entirely on batteries that the pilots must manually switch into circuit... Assuming they're not too busy trying to fly with whatever is left still functioning...)

... And why oh why is there no battery power for the CVR and FDR?...

... And the Boeing paper checklists are far too long by far...

Fly safe?
Martin


RAT: Ram Air Turbine to provide emergency electrical supply
CVR: Cockpit Voice Recorder
FDR: Flight Data Recorder

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While the B737NG doesn't have a RAT it does have an APU - but that has to be manually started, and those instructions are a long way down the checklist forest so the crew probably didn't reach that point....

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

Did they even get beyond the memory items? Either they were so badly trained as to have panic set in or something said this plane won't fly long enough to run the checklists.

The memory items are normally only the first few steps of a much larger checklist.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

(They rely entirely on batteries that the pilots must manually switch into circuit... Assuming they're not too busy trying to fly with whatever is left still functioning...)

Really? Unbelievable.

Well....
It's all to do with some aspects of the newer generations of the B737 having to be "the same" as on the very first generation, and it would appear that these recording devices weren't considered to be safety critical thus didn't need to be running all the time - hence no emergency power. Why the APU and standby battery systems need to be manually selected if the primary power is lost in flight is all down to history, and in this case totally crazy.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

It's a great shame that the data recorders don't have the data to the end of the flight- but hopefully what was recorded will give some idea of what went on in the lead up to the crash.
But whatever happened with the aircraft, i suspect a look at the flight crews training and their evaluations will become a very significant part of the investigation.

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Grant
Darwin NT

Not to forget that without the crazy design of the runway, with this massive wall just behind the end of the runway and the opposite direction's approach lights on massive and tall concrete foundations, such a deadly catastrophe would never have developed.

Not to forget that without the crazy design of the runway, with this massive wall just behind the end of the runway and the opposite direction's approach lights on massive and tall concrete foundations, such a deadly catastrophe would never have developed.

The non-frangible nature of the setup at the end of the runway made the accident worse than it should have been. Yes- It was a contributing factor to the severity of the crash, however it had absolutely no bearing on the cause of the crash, which was the aircraft touching down almost halfway down the length of the runway.

Even with the undercarriage down, and full braking & reverse thrust available, the aircraft would have still over-run the runway. And that late touchdown- the casue of that is what needs to be determined to avoid a repeat of this crash in the future, as there are many, many runways around the world that do have frangible structures at the end of them, but have hills, cliffs, rivers or oceans/lakes right at the end of them- even closer than the berm was in this instance.

Had it touched down in the actual touch down zone, even with it's high landing speed with no reverse thrust & no landing gear down, it would have stopped well before the end of the runway.


US Airways flight 1549 (Miracle on the Hudson) occurred during take-off- this suspected bird strike incident occurred during landing. If your approach is un-stabilised but have sufficient power for a go around, then go around. When on a stabilised approach, if a bird strike occurs, continue landing. If the approach is un-stabilised, but you don't know the status of your engines, continue landing.
These are factors in the cause of the accident, the berm at the end of the runway isn't. It is only factor in the severity of the accident.

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Grant
Darwin NT

Thank you for summarizing the facts in such a comprehensible way. This is not immediately obvious to laypeople without a deeper knowledge of aviation.

What bothers me the most is the timing of the sequence. Go around I get. But why the rush to get back to the airport? If you had the power to climb for the go around you have the power to climb to a safe altitude to take ten or fifteen minutes to run all the checklists and reconfigure for landing. Did something happen (or was indicated) on that go around that convinced the pilots to land immediately? If so that could account for the unstabilized approach. It is going to take the lab guys at least a year to get all the pieces under a microscope.

And all of us are assuming the bird strike is the only event that happened,

What bothers me the most is the timing of the sequence. Go around I get. But why the rush to get back to the airport? If you had the power to climb for the go around you have the power to climb to a safe altitude to take ten or fifteen minutes to run all the checklists and reconfigure for landing. Did something happen (or was indicated) on that go around that convinced the pilots to land immediately?

This is why it's such a problem that there is no CVR or FDR data for that period, and why pilot training and their evaluations will be so critical IMHO.

Many of the posts i've seen by other commercial pilots are all asking the same questions- why didn't they continue the landing? Why did they do the go around? Did they attempt the go around thinking they had enough power to do so but they didn't actually take the time to check the output from both engines, and once they commenced the go around, they then realised they didn't have enough power to actually do so- hence the tear drop manoeuvre back to the airport as a panic rush job, and turning too early to actually be able touchdown near the start of the runway, and ending up half way down with no flaps, no slats & no under carriage & way too much speed.

And if they realised early on enough to do the tear drop manoeuvre that they didn't have enough power to do a go around properly, why did they do the tear drop manoeuvre instead of ditching in the water that was just 1100 metres from the end of the runway?

And all of us are assuming the bird strike is the only event that happened,

It was most likely the initial cause of the whole sequence of events that led to the crash, but my personal suspicion is that decisions & actions performed by the crew resulted all the other issues that occurred, which led to their following decisions that led to the eventual crash as it occurred (the number of times a crew has shut down the working engine and not the faulty one are way too many).

One rushed/panicked decision probably as a result of a startle response, results in further issues and their alerts and warnings which further cognitively overload the crew leading to further poor decisions and yet more alerts & warnings, and without plenty of altitude to give you time to stop & reset and go through the Quick Reaction Index then there's no hope of recovery...
I don't like to speak ill of the dead, but it's looking more & more like what would have been a landable flight simulator training scenario, becoming a tragedy due to crew shortcomings.

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Grant
Darwin NT

Just seen this, not read it yet, https://www.reuters.com/world/asia-pacific/bird-feathers-blood-found-two-engines-boeing-jet-that-crashed-south-korea-source-2025-01-17/

Just seen this, not read it yet, https://www.reuters.com/world/asia-pacific/bird-feathers-blood-found-two-engines-boeing-jet-that-crashed-south-korea-source-2025-01-17/

It will be very interesting to see what comes of the full engine examination.

The real head scratcher with this incident is the timing- 4 minutes before the crash, ADS-B and FDR and CVR all stop functioning- common factor in all devices- electrically powered.
Both engines provide AC & DC power, and there are battery backups for flight control systems.

The aircraft had enough power in order to climb (at least for a short period), turn around, fly back towards where they came from, turn around again and come in to attempt to land, all while maintaining altitude.
While the pilots decisions very well may have lead to the plane crashing instead of landing, it still begs the question- what happened to cause a system wide power failure, even though the engines were still producing thrust??? (one theory is surges causing both generators to trip out (tripping due to frequency excursion), overwhelmed with everything else going on, the flight crew didn't see or recognise that warning amongst all the others & didn't reset the electrical Bus breakers to restore that electrical power).


An interesting and very relevant thread over at PPRuNe (Professional Pilots Rumour Network)
Shutting down the wrong engine

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Grant
Darwin NT

Shutting down the wrong engine is a repeating story on the Boeing 737...

... So why has that not been fixed?...


Meanwhile, we have no idea yet for this deadly example.

Fly safe folks?
Martin

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See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT (GPLv3)