Those devices are designed to withstand a great deal of abuse.

I am most likely crazy by now but something does not pass the smell test right off. To me, it sounds like some person or agency (Powerful person or agency) might have done a boo boo worth hiding.

Yeah, I am crazy.

...because they couldn't access data from one of the two recorders and sent it off to the NTSB to have its electronics repaired. The NTSB repaired it and found the four minutes missing, while the Korean investigators tried to get data off the other recorder and found the same.

Since these losses happened just after the reported bird strike, it seems to point to the hypothesis that the right-side engine was lost because of the bird strike, and the crew accidentally shut down the left-side engine instead, basically killing the power. That same scenario happened once before, with a British MIdlands flight back in 1989, an incident now known as the Kegworth air disaster.

Last edited Sun Jan 12, 2025, 10:23 AM - Edit history (1)

Also happened in a Taiwanese flight in Taipei and also in a flight off of Hawaii

see:
https://en.wikipedia.org/wiki/TransAsia_Airways_Flight_235
&
https://en.wikipedia.org/wiki/Transair_Flight_810

and find the data missing? Just wondering.

It will most likely come down to pilot error, black boxes or not.

The go around after a bird strike was a bad idea.

Accident in 2008:
The final report of the bird strike accident of Ryanair 4102 on short final has some interesting suggestions, what do do, when you encounter bird strike on short final:

Quote Boeing's recommendations (page 90):

In case of bird strikes during approach or landing, the following suggestion is given: "If the landing is assured continuing the approach to landing is the preferred option..."

Quote from Airbus' recommendations (page 91):

The prevention strategies indicated in this regard suggest, in case of birds presence in short final, not to go around, but to penetrate/fly through the flock and continue for landing, trying to maintain a low engine setting."

Quote from the UK CAA recommendations (page 91):

At approach thrust settings ingested birds may bypass the engine core via the fan reducing the likelihood of serious damage. If birds are encountered at approach thrust settings and landing can be made with that thrust setting, continue through the flock and complete the landing.

So it looks like hitting birds at TOGA settings is the worst case

Could be of two things, resulting in total electrical failure and- since someone was being cheap when they initially bought the plane in 2009 (ahem RyanAir) - they opted to not have a battery backup. Either a bird strike on BOTH engines, one of which ran for a little longer than the other and allowed the go around (rare but possible) or pilot error in shutting down the wrong engine (#1) after the bird strike on engine #2 (also rare, but there are documented cases of this happening too). For what it is worth, my money is on crew error/ pilot panic. There is video of the bird strike on engine #2. The engines were running long enough to retract the flaps all the way on approach. We know the reverser on #2 was deployed at landing. Video doesn't show any heat or exhaust from #1 on landing. Video DOES show heat / exhaust from #2 at landing so there was some power to it. It adds up to engine #1 being shut down. Time will tell if it was due to a "normal" albeit incorrect shut down or bird strike via the data on the recorder up to the point of loss.

Thanks for posting it!

Red-eye with a green Co-pilot not the best time for issues, plus Korean airlines have had CRM issues in the past. (Crew Resource Mang)

Also a go-around may have been the wrong move:

The final report of the bird strike accident of Ryanair 4102 on short final has some interesting suggestions, what do do, when you encounter bird strike on short final:

Quote Boeing's recommendations (page 90):

In case of bird strikes during approach or landing, the following suggestion is given: "If the landing is assured continuing the approcah to landing is the preferred option..."

Quote fron Airbus' recommendations (page 91):

The prevention strategies indicated in this regard suggest, in case of birds presence in short final, not to go around, but to penetrate/fly through the flock and continue for landing, trying to maintain a low engine setting."

Quote from the UK CAA recommendations (page 91):

At approach thrust settings ingested birds may baypass the engine core via the fan reducing the likelihood of serious damage. If birds are encountered at approach thrust settings and landing can be made with that thrust setting, continue through the flock and complete the landing.

So it looks like hitting birds at TOGA settings is the worst case.

Hard to argue they needed the hull clean to extend the glide when they miss half the runway going way too fast & get caught in ground effects.
If they had put her down at the threshold even at that speed I doubt it would have made it to the embankment with any energy/speed if at all.

To lose power 4 Minutes out, whatever the problem was too big to land safely must have lost all Power

These black boxes are designed to withstand water, pressure, fire, etc.

How convenient for the airlines and airport to have missing data.

The problem isn't damage to the recorders, but an electrical system failure while the plane was still in the air. When you lose power, the recording stops.

Interesting. Any analysis?

or preventing huge liability or jail time, it is only prudent to ask some questions and be skeptical.

This is human nature. Yes my analysis is based upon being a keep observer of human nature my entire life.
And being a therapist for over 40 years.

Airport and airlines screwed up big time. Killed a plane load of people due to their mistakes.
And the evidence goes missing.
Sure.

Chain of custody would have went from the Korean Air accident investigation service straight to the NTSB

All the while without power.
Are we seriously suggesting all the telemetry can be lost mid-flight?
I’d guess this is very convenient for Boeing.

A bird strike followed by most likely pilot error. Boeing didn't make the aircraft engines and they offered the data recorders with batt backup in 2009, somebody checked "no" when Ryanair bought the plane new & Jeju Airlines did not retrofit them.

Batt backup mandatory on new planes since 2010.

Went to aviation sites.

From what I gather after a half-dozen sites intended for aviator and aviation fans, black boxes have three power sources.

Both black boxes are powered by one of two power generators that draw their power from the plane's engines. One generator is a 28-volt DC power source, and the other is a 115-volt, 400-hertz (Hz) AC power source.

https://science.howstuffworks.com/transport/flight/modern/black-box.htm

This is the same specs found on multiple sites, so probably good (or at least not challenged, that I can find). But notice, the generators draw power from the engines, they are *not* batteries nor do they have separate fuel supplies.

Some sites explicitly refer to a battery power supply. This was confusing because others refer to the two generators. Turns out both are likely correct:

The beacon sends out pulses at 37.5 kilohertz (kHz) and can transmit sound as deep as 14,000 feet (4,267 meters). Once the beacon begins pinging, it pings once per second for 30 days. This beacon is powered by a battery that has a shelf life of six years. In rare instances, the beacon may get snapped off during a high-impact collision.

So the recorders, that take more juice, are connected to an external powers supply. That fails, when the magnetic field in the generator collapses there's no more current to run the recorders. But the beacon's power supply will keep on powering the beacon.

So if the power from the engines stops for whatever reason, no more recorded telemetry. And, yes, since the black boxes aren't located anywhere near the cockpit, if something interrupts the source of the telemetry--like the transmission lines or wifi signal is stopped--telemetry is lost and if they have power they record nothing.

One for the plane. One for the black box.

They're powered solely by the main aircraft busses. There is an external battery inside the pinger but it isn't actually attached to anything else electrically.

the airplanes never thought that there might be a power failure so they didn't bother with redundancies. In commercial aircraft the redundancies have redundancies.

there is no data to record. It looks increasingly likely that’s what happened to this flight, although the 737 has an emergency battery that should have powered the electrical systems for 15-30 minutes. Why that didn’t happen will be a question investigators have to answer. Also, if the battery was offline there would be no way to start the APU.

The APU has an electric starter that will drain most of the battery. That 15-30 min that the battery will supply power to the essential bus (which BTW only powers "essential" systems, the recorders aren't essential) drops to about 0-5 minutes if the APU doesn't actually start.

They had a lot to do in a short time & crew resource management may have been poor, it was a redeye flight & the Co-pilot only had 1,600hrs, not optimal for emergencies and Korean airlines have had CRM issues in the past.

Last edited Sat Jan 11, 2025, 07:11 PM - Edit history (1)

This plane was a 2009 ordered without it by Ryanair.

Lots of discussion @ Airliners.net about how they could have lost both generators but still had enough thrust for a go around, best theory IMO so far involves tripping breakers:


The recorders will still cover the period from the initial (likely) birdstrike to whatever caused the second generator to go offline. That will tell us what went wrong at first, and likely indicate what caused the loss of each generator (excessive N2 variation, flameout, shutdown).

At the point when ADS-B cut out, they were ~500ft and didn't have nearly enough energy to overfly the runway and do a teardrop without further thrust, so at least one engine was producing at least partial thrust for a good chunk of that 4-minute period. You can't glide for four minutes from that, let alone accelerate to ~200kt. 1549 glided for about 10nm; this flight would have been about three-quarters that length it appears, scaling off some peoples' indicative tracks, plus with much more turn (which eats up energy).

The generators on the 737 do not automatically come on bus. Flight crew action is needed to reset them if they trip. I am wondering if the stalls caused changes in N2 RPM that were too fast for the constant speed drive to handle, so frequency excursion tripped the generator off bus.

I think this somewhat fits the 'shut down wrong engine' hypothesis. GEN 2 (probably) dropped offline during the initial birdstrike. GEN 1 dropped offline when the crew shut down engine 1, or possibly during a separate second birdstrike, but I feel this is unlikely.

Like in Transair 810, the failed engine continued providing not quite enough thrust to maintain level flight, forcing this flight to attempt a teardrop to land.

If the interconnects are severed in the tail, there is no data.

This aircraft did not crash. They successfully landed on their belly. If not for the concrete ILS berm, they would have slid to a stop.

I was an avionics tech both Marines and Douglas.

You're thinking of the Azerbaidjan-Russia-Kazakhstan crash. This was in South Korea, other side of the continent.

I'm distracted by our fires.
I can see it from my house.

they didn’t land for another 45 minutes or so. If they somehow lost normal power, the recorders would have died when the batteries did. Questions they need to answer include:

-Why did they remain airborne for so long after the initial event?

-Was there a total loss of generator power? Was there an attempt to start the APU? If not, why not?

-Was there an attempt to lower the gear? Using normal or emergency procedures? Same question for the flaps? Was hydraulic power available at all? Were the flight controls in manual reversion mode?

These are all questions the FDR and the CVR will be able to answer despite losing power at the end. It’s a head scratcher. I’ll wait for the data before I try to solve this one.

8:54L: Muan airport air traffic control clears the aircraft to land on runway 01
8:57L: Air traffic control broadcasts “caution - bird activity” advisory.
8:57:55 plane flies past massive flock of birds [farm CCTV]
8:58L: communications began to shows signs of interference and confusion. aircraft suddenly gained altitude, and witnesses reported hearing explosions accompanied by flames near the wing area [MBC News]
8:58:25L: altitude 450 ft, positive vspeed [FR24]
8:58:34L: altitude 625 ft, negative vspeed [FR24]
8:58:50L: The last ADS-B message received from the aircraft occurred at 23:58:50 UTC with the aircraft located at 34.95966, 126.38426 at an altitude of 500 feet approaching Runway 1 at Muan. [FR24]
8:59L: pilot reports bird strike, declares emergency “Mayday Mayday Mayday” and “Bird strike, bird strike, go-around.”
9:00L: initiates a go-around and requests authorisation to land on runway 19, which is by approach from the opposite end of the airport’s single runway.
9:01L: Air traffic control clears the aircraft to land on runway 19.
9:02L: touches down on the runway about 1,200m (3940 feet) down on the 2,800m (9184 feet) long runway.
9:02:34L: Air traffic control alerts “crash bell” at airport fire rescue unit.
9:02:55L: Airport fire rescue unit completes deploying fire rescue equipment.
9:03L: crashes into embankment after over-shooting the runway.

By something incoming?