4 ms·

Jeju Air jet black boxes stopped recording before crash: transport ministry

24 points by gslin 2y ago

miohtama 2y ago
It is quite a coincidence. Is it possible that "some buffer just did not flush" as in software development may happen.
- jdright 2y ago
  4 minutes is too long for a "missed flush". This looks like bad software simply. One may wonder if it is also developed by Boeing.
  - dmix 2y ago
    Boeing only integrates the black box to the planes they don’t develop them. They are made by companies like Honeywell Aerospace
- SlightlyLeftPad 2y ago
  I’ve studied this in older aircraft, and no that was possible because it was recorded directly to tape that records over itself in a loop. I’m not sure if that’s still true on newer planes.
  - dmix 2y ago
    There was a case where a black box tape recorder missed the last 6 minutes https://en.wikipedia.org/wiki/Swissair_Flight_111?wprov=sfti1 https://en.wikipedia.org/wiki/Swissair_Flight_111?wprov=sfti...
flocciput 2y ago
not the same article, but same subject with more discussion: https://news.ycombinator.com/item?id=42664097 https://news.ycombinator.com/item?id=42664097
chuckwfinley 2y ago
"The analysis revealed that both the CVR and FDR data were not recording during the four minutes leading up to the aircraft's collision" How does this even happen where two systems would stop recording data. This story seems to get weirder and weirder. I'd always been under the impression that black boxes were really highly secure and extremely rigorously developed to specifically prevent data loss in situations like this. Bad enough for the accident to occur, but to not have accurate telemetry and recorded data from the onboard systems is definitely going to make an already hard investigation very much harder
- denysvitali 2y ago
  It might still give us some hints. In the other thread they say that the black box might have stopped recording because of a power failure - and planes manufactured before 2010 (this plane was from 2009) didn't need an UPS. The hint that we get from this news is that the plane (or better, the blackbox) was missing electricity for 4 minutes prior to the crash.
  - henearkr 2y ago
    I think you have a typo either on 2019 or on 2010.
    - class700 2y ago
      Plane was built in 2009.
    - denysvitali 2y ago
      2009, sorry. Fixed! Thanks!
- cameronh90 2y ago
  According to 737NG technical diagrams I found online, the CVR is powered by the XFER BUS 2, and the FDR by the DC BUS 1. Neither of these busses can operate from the battery, but both should be operating if either engine or the APU is running, provided all switches are in the correct position. On the surface it seems odd to not run the CVR/FDR from battery, but on the other hand it’s not a critical flight system. This suggests either dual engine failure, or single engine failure followed by shutting down the wrong engine with the fire handle (which cuts off electrical power), or (unlikely) a catastrophic electrical system failure. This isn’t a new interpretation, since the ADSB transponder also shut down at about the same time which led many to assume the electrics had gone out for some reason. My guess remains that they shut down the wrong engine given that the reported bird strike occurred (reportedly) a few minutes before the plane seems to have lost power, but the timeline is still not certain. However, it did seem like the engine that had the mobile footage with the compressor stalls was still running at landing which should usually be enough to generate electricity since even windmilling is enough, which adds another wrinkle. Perhaps the bird strike destroyed the generator?
yread 2y ago
Easiest explanation is that they were not powered. They are on a bus that doesn't get power from the battery on 737, they need either APU (doors of which were found half closed on the wreck) or one of the engine generators. That would explain lack of gear, slats and flaps, too.
- fooqux 2y ago
  I'm learning today that black boxes don't have any sort of built-in emergency battery power, apparently. For a device that is meant to be a data gatherer up until the "last gasp" of the airplane, that seems like a pretty obvious design flaw to me. Does anyone know why?
  - Filligree 2y ago
    It’s a mystery, and according to a cousin post, black boxes from planes manufactured recently do have backup power.
  - tgsovlerkhgsel 2y ago
    Money. Adding a battery adds cost and weight (and complexity, but we know how to engineer and maintain things properly). The cost/weight would have been a lot more prohibitive decades ago when the rules were made, and regulators are slow to adapt.
    - dredmorbius 2y ago
      And for every additional kilogram or pound of weight, a typical 2000mi / 3200 km flight will consume an equivalent mass of fuel. Conventional (fuel-powered) aircraft, and to an even greater extent battery-powered aircraft, are absolute marvels of light-weighting engineering, driven by both materials and designs. As FDR/CVR are used only once, and that in a vanishingly small fraction of aircraft, the cost considerations of carrying additional mass are high. It's not just the aircraft that crash, but all aircraft across the entire global commercial fleet. That's on the order of 32,000 aircraft presently, each with multiple flight cycles per day on average.[1] That's on the order of 50--100 tonnes of fuel consumption per day if the total added weight is limited to 1 kg. Black boxes must also survive crash conditions. A battery itself might be a fire risk, and would require additional material to protect both itself and the data storage of a black box in the event of an accident. That said ... one would think that current lightweight battery packs might make short-term battery operation reasonably viable. -------------------------------- Notes: 1. "Information supplied by aviation data specialists ch-aviation shows that at as of July 7, there were 31,734 civil aircraft in the global fleet being used by more than 750 different airlines. " <https://www.key.aero/article/how-many-commercial-aircraft-are-there-world https://www.key.aero/article/how-many-commercial-aircraft-ar...> Story appears to be from 2020 per Internet Archive: <https://web.archive.org/web/20200929012536/https://www.key.aero/article/how-many-commercial-aircraft-are-there-world https://web.archive.org/web/20200929012536/https://www.key.a...>.
pupppet 2y ago
> Investigators have pointed to a bird strike, faulty landing gear and the runway barrier as possible issues. That runway barrier, “possible issue”.
- tgsovlerkhgsel 2y ago
  The runway barrier didn't make the plane fail to extend its landing gear and overrun the runway. It certainly contributed to the severity but it doesn't explain the incident.
  - pupppet 2y ago
    It should most definitely be included among the “possible issues”
poopsmithe 2y ago
Federal Express Flight 705 comes to mind, in which a crew member disabled the CVR by pulling it's circuit breaker before attempting to hijack the plane.
deleted 2y ago
[deleted]
oysterville 2y ago
Dupe:https://news.ycombinator.com/item?id=42664097 https://news.ycombinator.com/item?id=42664097
ChrisArchitect 2y ago
[dupe] https://news.ycombinator.com/item?id=42664097 https://news.ycombinator.com/item?id=42664097

24 points by gslin 2y ago

miohtama 2y ago

It is quite a coincidence. Is it possible that "some buffer just did not flush" as in software development may happen.

jdright 2y ago
4 minutes is too long for a "missed flush". This looks like bad software simply. One may wonder if it is also developed by Boeing.
- dmix 2y ago
  Boeing only integrates the black box to the planes they don’t develop them. They are made by companies like Honeywell Aerospace
SlightlyLeftPad 2y ago
I’ve studied this in older aircraft, and no that was possible because it was recorded directly to tape that records over itself in a loop. I’m not sure if that’s still true on newer planes.
- dmix 2y ago
  There was a case where a black box tape recorder missed the last 6 minutes https://en.wikipedia.org/wiki/Swissair_Flight_111?wprov=sfti1 https://en.wikipedia.org/wiki/Swissair_Flight_111?wprov=sfti...

flocciput 2y ago

not the same article, but same subject with more discussion: https://news.ycombinator.com/item?id=42664097 https://news.ycombinator.com/item?id=42664097

chuckwfinley 2y ago

"The analysis revealed that both the CVR and FDR data were not recording during the four minutes leading up to the aircraft's collision" How does this even happen where two systems would stop recording data. This story seems to get weirder and weirder. I'd always been under the impression that black boxes were really highly secure and extremely rigorously developed to specifically prevent data loss in situations like this. Bad enough for the accident to occur, but to not have accurate telemetry and recorded data from the onboard systems is definitely going to make an already hard investigation very much harder

denysvitali 2y ago
It might still give us some hints. In the other thread they say that the black box might have stopped recording because of a power failure - and planes manufactured before 2010 (this plane was from 2009) didn't need an UPS. The hint that we get from this news is that the plane (or better, the blackbox) was missing electricity for 4 minutes prior to the crash.
- henearkr 2y ago
  I think you have a typo either on 2019 or on 2010.
  - class700 2y ago
    Plane was built in 2009.
  - denysvitali 2y ago
    2009, sorry. Fixed! Thanks!
cameronh90 2y ago
According to 737NG technical diagrams I found online, the CVR is powered by the XFER BUS 2, and the FDR by the DC BUS 1. Neither of these busses can operate from the battery, but both should be operating if either engine or the APU is running, provided all switches are in the correct position. On the surface it seems odd to not run the CVR/FDR from battery, but on the other hand it’s not a critical flight system. This suggests either dual engine failure, or single engine failure followed by shutting down the wrong engine with the fire handle (which cuts off electrical power), or (unlikely) a catastrophic electrical system failure. This isn’t a new interpretation, since the ADSB transponder also shut down at about the same time which led many to assume the electrics had gone out for some reason. My guess remains that they shut down the wrong engine given that the reported bird strike occurred (reportedly) a few minutes before the plane seems to have lost power, but the timeline is still not certain. However, it did seem like the engine that had the mobile footage with the compressor stalls was still running at landing which should usually be enough to generate electricity since even windmilling is enough, which adds another wrinkle. Perhaps the bird strike destroyed the generator?

yread 2y ago

Easiest explanation is that they were not powered. They are on a bus that doesn't get power from the battery on 737, they need either APU (doors of which were found half closed on the wreck) or one of the engine generators. That would explain lack of gear, slats and flaps, too.

fooqux 2y ago
I'm learning today that black boxes don't have any sort of built-in emergency battery power, apparently. For a device that is meant to be a data gatherer up until the "last gasp" of the airplane, that seems like a pretty obvious design flaw to me. Does anyone know why?
- Filligree 2y ago
  It’s a mystery, and according to a cousin post, black boxes from planes manufactured recently do have backup power.
- tgsovlerkhgsel 2y ago
  Money. Adding a battery adds cost and weight (and complexity, but we know how to engineer and maintain things properly). The cost/weight would have been a lot more prohibitive decades ago when the rules were made, and regulators are slow to adapt.
  - dredmorbius 2y ago
    And for every additional kilogram or pound of weight, a typical 2000mi / 3200 km flight will consume an equivalent mass of fuel. Conventional (fuel-powered) aircraft, and to an even greater extent battery-powered aircraft, are absolute marvels of light-weighting engineering, driven by both materials and designs. As FDR/CVR are used only once, and that in a vanishingly small fraction of aircraft, the cost considerations of carrying additional mass are high. It's not just the aircraft that crash, but all aircraft across the entire global commercial fleet. That's on the order of 32,000 aircraft presently, each with multiple flight cycles per day on average.[1] That's on the order of 50--100 tonnes of fuel consumption per day if the total added weight is limited to 1 kg. Black boxes must also survive crash conditions. A battery itself might be a fire risk, and would require additional material to protect both itself and the data storage of a black box in the event of an accident. That said ... one would think that current lightweight battery packs might make short-term battery operation reasonably viable. -------------------------------- Notes: 1. "Information supplied by aviation data specialists ch-aviation shows that at as of July 7, there were 31,734 civil aircraft in the global fleet being used by more than 750 different airlines. " <https://www.key.aero/article/how-many-commercial-aircraft-are-there-world https://www.key.aero/article/how-many-commercial-aircraft-ar...> Story appears to be from 2020 per Internet Archive: <https://web.archive.org/web/20200929012536/https://www.key.aero/article/how-many-commercial-aircraft-are-there-world https://web.archive.org/web/20200929012536/https://www.key.a...>.

pupppet 2y ago

> Investigators have pointed to a bird strike, faulty landing gear and the runway barrier as possible issues. That runway barrier, “possible issue”.

tgsovlerkhgsel 2y ago
The runway barrier didn't make the plane fail to extend its landing gear and overrun the runway. It certainly contributed to the severity but it doesn't explain the incident.
- pupppet 2y ago
  It should most definitely be included among the “possible issues”

poopsmithe 2y ago

Federal Express Flight 705 comes to mind, in which a crew member disabled the CVR by pulling it's circuit breaker before attempting to hijack the plane.

deleted 2y ago

[deleted]

oysterville 2y ago

Dupe:https://news.ycombinator.com/item?id=42664097 https://news.ycombinator.com/item?id=42664097

ChrisArchitect 2y ago

[dupe] https://news.ycombinator.com/item?id=42664097 https://news.ycombinator.com/item?id=42664097