737-500 lost contact after takeoff

[threexgreen 3,156]

1 hour ago, Ray Proudfoot said:

@threegreen, so the transponder was working all the way down. That would appear to rule out a mid-air breakup.

Even if both engines flamed out an aircraft can still be controlled which is why that descent profile is so mystifying.

It's hard to say if it could have been a stall because it's only ground speed which is displayed on the graph. Perhaps someone else here has a Flightradar24 subscription and could post the indicated airspeed.

The profile could show the loss of airspeed in response to a high angle of attack until loss of lift and the subsequent rapid increase resulting from going down and recovering somewhat. It's what I thought at first, but a second look makes it seem like a strange profile for a stall because of how sudden and steep the loss of airspeed is, occurring in just a few seconds, rather than a longer process with a curve that's slowly starting to go downwards and only then rapidly decreasing. Although it could of course be down to an inaccuracy of the data transmission or the data itself. What's also speaking against a stall is how there seems to be no sign of recovery at all even though the supposed stall would have started at above 10000 feet.

[HighBypass 2,339]

2 hours ago, Ray Proudfoot said:

Mark, what sort of bad weather could cause an aircraft to fall out of the sky like that?

Not much. However, I wasn't implying that the weather caused the crash, I was just wondering about the dogleg turn before the FR24 data stopped.

[Ray Proudfoot 9,041]

11 minutes ago, HighBypass said:

Not much. However, I wasn't implying that the weather caused the crash, I was just wondering about the dogleg turn before the FR24 data stopped.

I know you weren’t. I’m struggling to understand how an aircraft can just fall out of the sky like that. You imagine Tower or Departure would have issued weather advisories if there were storms on the departure track. The black box voice recorder may give some clues.

Maybe the turn was initiated because of a problem handling the aircraft. The pilot’s experience will be an interesting factor.

[Chock 17,769]

Sad to hear about this and I'm as curious as anyone to know what occurred, but in this case I think any suggestions we make as to what we think might be the cause can only be wild guesses. The very high rate of decent is reminiscent of a few precedents, and of these, partial mid-air break up possibly due to weather or fatigue/maintenance issues, deliberate crashing (sadly a not unknown phenomenon), or rudder hardover and subsequent dive, seem the most likely candidates, but beyond these avenues, it's all just speculation.

Hopefully the FDR and CVR will be able to help determine what occurred and at least give the relatives of those on board some kind of help toward closure in what I can only imagine must be an awful thing to experience.

Although not a MAX variant, this is also the last thing Boeing needed at this point, as most people just see '737' on the news, and off they go.

Edited January 9, 2021 by Chock

[CYXR 257]

19 minutes ago, Chock said:

Hopefully the FDR and CVR will be able to help determine what occurred and at least give the relatives of those on board some kind of help toward closure in what I can only imagine must be an awful thing to experience.

Apparently the have the four corners of the aircraft; the sea of Java is shallow. They should find the recorders. Let`s hope their data can be analysed to help understand and prevent what happenned.

[ahsmatt7 1,201]

7 hours ago, Ray Proudfoot said:

Thanks Peter. Correction made. I saw the recreation of it on Nat Geo Air Crash Investigation programme. They flew into the wake of a Japan 747 and the first officer followed the procedure he had been taught to correct the problem. Those were modified after the investigation.

Well, the FO was using too much rudder for the required corrections. The NTSB noticed the trend based off his training records and interviews from other captains he flew with. 
 

crazy stuff for sure!

[Antipodeslonghaul 80]

PK-CLC had been flying since around 5 am that morning and was apparently on its 5th leg for the day. Highly unlikely to have been any sort of insect's nest in a pitot tube. And although it can get very dark while inside t-storm cells, it was the early afternoon, the horizon may have been visible outside if they were in partial VMC at least. So two major differences to my earlier reference to Birgenair 301, that plane, a 757, had been sitting unused for 20 days, and without the pitot tube covers in place for the preceding 2 days before the crash. Also Birgenair had departed around midnight local time. Had they departed in daylight and been able to see the horizon, they might not have pitched up as dramatically as they did, since it seems unlikely they had been properly scanning their instruments anyway. 

Just a few thoughts that my earlier hunch that there might have been any similarity to the Birgenair crash now seem way more distant.

[mazelda 124]

If the outcome is a tail separation then i'm sure the investigators will be looking closely at the rudder pcu. The 737 has had at least 2 accidents in the past that have been caused by pcu problems, and if there was a failure of the rudder limiter then very possibly with a rudder input at speed would be enough to rip the back end off.

To drop that quick suggests some sort of catastrophic failure unfortunately

[Ray Proudfoot 9,041]

BBC reporting the two black boxes have been located. The sea is shallow in the region so recovery should not take long.

[psolk 3,057]

Wow, holy speculation in this thread.... 

17 hours ago, Ray Proudfoot said:

I know you weren’t. I’m struggling to understand how an aircraft can just fall out of the sky like that. You imagine Tower or Departure would have issued weather advisories if there were storms on the departure track. The black box voice recorder may give some clues.

Maybe the turn was initiated because of a problem handling the aircraft. The pilot’s experience will be an interesting factor.

Just look at the AF447 pilots who put their plane into a stall after airspeed inconsistencies... 

[Ray Proudfoot 9,041]

6 minutes ago, psolk said:

Wow, holy speculation in this thread.... 

Just look at the AF447 pilots who put their plane into a stall after airspeed inconsistencies... 

Not speculation. Just people offering views on what the cause might be.

Very different circumstances. That aircraft was at cruise with two relatively inexperienced pilots as the captain was taking a break. Frozen pitot tubes caused confusion and for some inexplicable reason they tried to climb out of a stall. 🙄

[psolk 3,057]

19 minutes ago, Ray Proudfoot said:

Not speculation. Just people offering views on what the cause might be.

Very different circumstances. That aircraft was at cruise with two relatively inexperienced pilots as the captain was taking a break. Frozen pitot tubes caused confusion and for some inexplicable reason they tried to climb out of a stall. 🙄

Isn't that the definition of speculation?    According to Cambridge:  The act of guessing possible outcomes without enough information to be certain... 

Catastrophic failure

Tail/Rudder separation issues (not known to be a 737 issue that I'm aware of)

Putting Pilot action as "least likely"  (I strongly disagree here)

Dual engine flame out rendering a plane controllable because the transponder was working...

All speculation. It's just taking wild guesses at this point.  

You also asked how a plane can just fall from the sky.  AF447 (Pilot error) is an example of how regardless of cruise/ pilot rest etc etc...

Quote

“There has been a lot of noise made about the speed of its final descent,” said Geoff Dell, an air accident investigation expert based in Australia. “It is indicative of what happened but why it happened is still in many ways a guess really. There are multiple ways you can get an aeroplane to go down at that pace.”

He said investigators would look into factors including mechanical failure, pilot actions, maintenance records, weather conditions and whether there was any unlawful interference with the plane. Most air accidents are caused by a combination of factors that can take months to establish.

 

VARIOUS FACTORS UNDER SCRUTINY

Sriwijaya’s operating record will also be placed under scrutiny.

“Its safety record has been mixed,” said Greg Waldron, Asia managing editor at industry publication FlightGlobal. He said the airline had written off three 737s between 2008 and 2012 due to bad landings that resulted in runway overruns, with the 2008 accident resulting in one death and 14 injuries.

The airline in late 2019 ended a year-long partnership with national carrier Garuda Indonesia and had been operating independently.

Just before ending the pact, more than half of Sriwijaya’s fleet had been grounded by the Transportation Ministry due to airworthiness concerns, according to media reports at the time.

Sriwijaya did not respond immediately to a request for comment. The airline’s chief executive said on Saturday the plane that crashed was in good condition.

Like other Indonesian carriers, Sriwijaya had slashed its flight schedule during the COVID-19 pandemic, which experts said will be examined as part of the investigation.

“The challenges that the pandemic brings impacts aviation safety,” said Chappy Hakim, an Indonesian aviation analyst and former air force official. “For instance, pilots/technicians were downsized, salaries not paid in full, planes are grounded.”

 

 

Edited January 10, 2021 by psolk

[Ray Proudfoot 9,041]

@psolk, the AF did not fall at over 20,000fpm. It was in a flat stall from which it couldn't be recovered. It was also at a very high altitude, not 10,000ft as in the case of yeaterday's accident.

Wild speculation or reasonably educated thoughts as to what might have happened. I think the latter is the case here. Feel free to offer your own opinion but don't accuse others of 'wild speculation' simply becasue they choose to discuss what might have happened.

[psolk 3,057]

8 minutes ago, Ray Proudfoot said:

@psolk, the AF did not fall at over 20,000fpm. It was in a flat stall from which it couldn't be recovered. It was also at a very high altitude, not 10,000ft as in the case of yeaterday's accident.

Wild speculation or reasonably educated thoughts as to what might have happened. I think the latter is the case here. Feel free to offer your own opinion but don't accuse others of 'wild speculation' simply becasue they choose to discuss what might have happened.

ok we will agree to disagree, reasonably educated thoughts as to what might have happened without fact is speculation. Not sure why that is a point of contention.  

As for my own opinion I agree with Geoff Dell who I quoted above.  

Quote

“There has been a lot of noise made about the speed of its final descent,” said Geoff Dell, an air accident investigation expert based in Australia. “It is indicative of what happened but why it happened is still in many ways a guess really. There are multiple ways you can get an aeroplane to go down at that pace.”

He said investigators would look into factors including mechanical failure, pilot actions, maintenance records, weather conditions and whether there was any unlawful interference with the plane. Most air accidents are caused by a combination of factors that can take months to establish.

Also:

Quote

 

The airline in late 2019 ended a year-long partnership with national carrier Garuda Indonesia and had been operating independently.

Just before ending the pact, more than half of Sriwijaya’s fleet had been grounded by the Transportation Ministry due to airworthiness concerns, according to media reports at the time.

 

 

Other than that I'm not speculating on anything.  

 

Edited January 10, 2021 by psolk

[HighBypass 2,339]

35 minutes ago, psolk said:

Wow, holy speculation in this thread.... 

I wasn't aware Fr.Bill had made any input to this thread yet 

In any case, none of us are the NTSB investigators tasked with the crash. Wild speculation or reasoned arguments - IM NSHO  these things are what make such threads an interesting topic for debate; some members have detailed knowledge of real world systems, some of us are just enthusiasts. 🍻