Sriwijaya Air flight SJ182 crash investigation

Flanders

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I've often wondered why they don't just change altitude and go above the storm. I know some storms can be very high but those plane's max ceiling is like 44 000 ft, at that height they should ride above most storms? And 44 000 is probably a very conservative safety number, they can prob hit 46-48k without issue - certain less issue than having the plane's components shoved and bounced around all of the place.

But in my discussions with Pilots it seems they have to obey their given flight altitude - and getting tossed about like a cheap kite is not a reason not to :(

44 000 ft is above most commercial airliners' service ceilings. Push the boundary and you risk entering into what's known as coffin corner.

From what I've learned, it seems to all be about profit - too expensive to fly higher. Typical...

Flying higher is actually more economical - less fuel burn. There is a fine balance though between optimal altitude and fuel load. An aircraft (especially long haul) must burn fuel in order to efficiently attain optimal fuel efficient altitude - known as a step climb.
 

Blu82

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Good question about the design of black boxes. Not delved into this aspect myself so I don't know.

Incidentally, a follow up on the Lear Jet crash due to oxygen system failure showed that a key cause was that the checklists at the time made the crew do all sorts of things before they got to the step calling for "donning of oxygen masks" and descending to a safe altitude. The ACI episode stated that after that incident, the checklist were changed for all aircraft flying at altitude to ensure the crew would don their masks first, then descend to a safe altitude and then only start fault finding of pressurisation systems.
There might be have been a pilot incapacitation related crash in the US over the last week. The final manouver by the aircraft is similar to what you would do on a depressurization event.
 

neoprema

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44 000 ft is above most commercial airliners' service ceilings. Push the boundary and you risk entering into what's known as coffin corner.



Flying higher is actually more economical - less fuel burn. There is a fine balance though between optimal altitude and fuel load. An aircraft (especially long haul) must burn fuel in order to efficiently attain optimal fuel efficient altitude - known as a step climb.
Interesting, i didn't know the two could meet at some point...
 

Brian_G

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  • Flight Data Recorder has been recovered from the seabed by diving team
  • Part of the cockpit voice recorder is still missing and could provide vital clues
  • Funeral for one of the victims - Okky Bisma, a flight attendant - held on Thursday
  • A reported 36 body bags have been recovered from the wreckage of flight SJ182
  • It plunged 10,000ft into the Java Sea within four minutes of takeoff from Jakarta
Naval officers said they had recovered the body and homing beacon portions of the voice recorder, and are now searching for the memory unit that could contain vital clues about what caused the plane to crash last Saturday, killing 62.


 

Gordon_R

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No meaningful data released yet. The fact that the engines were running is not particularly relevant. (Contrary to Hollywood myths, planes don't just fall out of the sky when the engines stop).

Keep track of futher updates here (but try to avoid reading the toxic comments section). http://avherald.com/h?article=4e18553c
 

Brian_G

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No meaningful data released yet. The fact that the engines were running is not particularly relevant. (Contrary to Hollywood myths, planes don't just fall out of the sky when the engines stop).
Though it does mean a likelihood that they still had power, and there's a stronger possibility now that this is either tail control related or that the crew were overcome.

Not that there aren't many other possibilities as well.
 

Brian_G

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Keep track of futher updates here (but try to avoid reading the toxic comments section). http://avherald.com/h?article=4e18553c
Some detailed photos there.

And this further info of interest;
On Jan 15th 2021 the KNKT reported that the data of the FDR have been successfully downloaded, all 330 parameters recorded are in good condition and are currently being analyzed.
A passenger booked onto the crashed flight reported, that he had to miss the flight due to his Covid-19 PCR Test results not yet having arrived. Only after the aircraft had already departed the (negative) test results arrived which would have permitted him to board the flight.
 

Brian_G

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Not sure how this causes a plane to fall out of the sky:
There was an episode of ACI which focused on a similar problem, caused utter chaos and confusion resulting in their crash but I can't recall more. May have been a visibility issue that added to such uncertainty.
 

Brian_G

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I read somewhere that the search is drawing to a close, anybody have any idea when? Maybe there won't be time to find the CVR :(
 

Gordon_R

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The preliminary report (based on the FDR only) blames asymmetric engine thrust, followed by pilot mishandling and loss of control:
When the 26-year-old Boeing Co 737-500 plane reached 8,150 feet (2,484 m) after take-off, the left engine throttle lever moved back while the right lever stayed in its original position, Indonesia’s National Transportation Safety Committee (KNKT) said in its report.
At about 10,900 feet, the autopilot disengaged and the plane rolled to the left more than 45 degrees and started its dive, according to the report.
There had been two prior problems reported with the autothrottle system that automatically controls engine power based on maintenance logs, but the issue was rectified on Jan. 5, four days before the crash, KNKT said.

A working autothrottle is not required for a plane to be dispatched as pilots can control the thrust levers manually with their hands.
The report highlighted the importance of upset recovery training for pilots and the recognition of repetitive plane defects, just over six years after an AirAsia Indonesia crash where those were among the issues raised.

KNKT said that following the crash Sriwijaya had taken safety actions including adding upset recovery training in its next pilot proficiency check and reminding engineers that repetitive defects must be handled in accordance with safety manuals.
 
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