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Indonesian B737-500 goes missing, 5 mins after takeoff from Jakarta.


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Reports are in that a Boeing 737-500, belonging to Sriwijaya Air, has disappeared off the radar, around 5 mins after taking off from Jakarta, bound for Pontianak in West Kalimantan. There were 56 pax on board, plus 6 crew.

 

FlightRadar24 is reporting the aircraft lost 10,000 ft in altitude in less than a minute, over the Java Sea. There are unconfirmed reports that fisherman in the area have found wreckage, but it is not clear at this point if the wreckage belongs to this aircraft.

 

Aircraft registration is PK-CLC (MSN 27323), and it was built in May 1994, making it well over 26 yrs old. The exceptionally rapid descent seems to indicate major catastrophic failure, an explosive device going off, or even possible pilot suicide.

 

Local fisherman and witnesses on the nearby Lancang Island reported hearing two loud explosions. The surface weather was stormy and raining intermittently at the time.

 

Water depth in the area where the wreckage was located, is reported as being around 15-16M deep.

 

https://www.abc.net.au/news/2021-01-09/indonesia-plane-loses-contact-sriwijaya-air-flight-sj182-jakarta/13045220

 

https://twitter.com/flightradar24/status/1347850078644563969

 

https://aviation-safety.net/database/record.php?id=20210109-0

 

http://avherald.com/h?article=4e18553c&opt=0

 

Edited by onetrack
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Reports are in that a Boeing 737-500, belonging to Sriwijaya Air, has disappeared off the radar, around 5 mins after taking off from Jakarta, bound for Pontianak in West Kalimantan. There were 56 pax

Well, the preliminary report is out, and it doesn't tell us all we'd like to know. But the FDR reveals an auto-throttle rollback problem - which should've been handled with ease by competent pilots -

Having been a passenger on Indonesian internal airline flights I would consider anything possible.

No radio calls, I wonder if there is any reporting equipment back to base with flight performance and engine info. Could this be a re run of a previous crash, that was never found?

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Juan Browne (blancolirio) has a nearly 10 min YouTube video on this incident - but he only goes over the details already known, and doesn't contribute anything major to the discussion - apart from the three following facts;

 

1. Explosive decompression as an initiator of the crash was unlikely to be a factor, due to the relatively low altitude of 10,000 ft.

2. He opines that the turbulent thunderstormy weather in the region of the crash, does not appear to be severe enough, to be a major factor in the crash.

3. The speed trim would be inoperative at the altitude the aircraft reached.

 

I'm surprised that he failed to mention turbulent air penetration maximum speed (Vb - 280kts KIAS), or manoeuvering speed (Va - 230 KIAS) for the B737-500.

The aircraft reached 284 Kts TAS and 287 Kts Ground Speed just before the initiation of the rapid track changes and altitude change.

While these are only indicative, they do give a clue that it's possible that either Va or Vb were exceeded, as the aircraft entered a patch of severe turbulence - or if it had banked to avoid a storm cell.

 

It is entirely possible that an excessive control input reaction by the PIC, in reaction to say, sudden, severe turbulence, or a lightning strike, right as Va or Vb were reached, may have caused excessive airframe stresses and catastrophic airframe failure.

However, as Juan Browne correctly points out, information from the CVR and the FDR will be the critical information required as to exactly what happened.

 

The Sriwijaya Air B737-500 has seating for 136 in economy, plus 3 in 1st Class. With a total of 62 POB, it would appear this aircraft wouldn't be anywhere near MTOW - unless some heavy freight was being carried.

 

Interestingly, of the 1988 Classic B737's built (with 389 B737-500's built), the crash rate for the Classic series, was a hull loss rate of 0.71 per million departures, versus 0.17 for the NG series. A total of 63 Classic B737's have now been lost.

 

The pickle fork cracking problems are not relevant to the Classic B737, the problem only appeared on the later B737 NG.

 

http://www.b737.org.uk/737classic.htm

Edited by onetrack
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Some of the earlier losses were due to the rudder power malfunctioning. That's been resolved but I wonder if it's reflected in those statistics  Nev

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49 minutes ago, jackc said:

I would be having a real close look at the maintenance records......

Doesn't mean much in Indo, maintenance records are as fictional as their pilots experience.

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Didn’t they just release the cleric bombing maniac? Surely a link is possible, his mates letting us know they are still in business.

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It's drawing a bit of a long bow to try and link the mad muzzie cleric, to this aircraft falling out of the sky.

 

It's not like it was full of God-bothering Westerners on a pilgrimage to convert 220 million Indonesians to Christianity.

 

The likelihood is high, that pilot error, or a maintenance stuff-up, will be behind the crash.

 

The main section of the wreckage has been located in 23M of water, the water is clear and visibility is good, and they have reportedly picked up pings from the aircrafts ELT.

 

The Indonesians have recovered quite a bit of wreckage - shattered panels, a shattered but reasonably complete wheel, luggage, wiring, an emergency slide, clothing, and 5 bags of body parts.

 

Everyone is hanging out to see and hear what's on the FDR and CVR.

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The passenger and crew list have been released. They all appear to be Indonesians.

 

The Captain, who goes by only one name, as in the common Indonesian custom, is Captain Afwan. He is a former IAF pilot. There appears to be no public record available of his career.

 

Captain Afwan appears in photos regularly as a very devout Muslim. He does not appear to have any LinkedIn account - but there's a news media report, with photos of him.

 

https://jabar.tribunnews.com/2021/01/10/status-whatsapp-atau-wa-terakhir-captain-afwan-disebut-jadi-pengingat-untuk-orang-ini-fotonya

 

His co-pilot was named as Senior F.O. Diego Mamahit. His LinkedIn account lists his total flying hours as 4800.

 

https://id.linkedin.com/in/diego-mamahit-75a39748?challengeId=AQEU6ZT9mCMwhwAAAXbr2TV-rk-Cgufpqby4m7H1dEnztgXFjbFLzTRdvczjQuzBkEU0WTQ7wQlJ2YTjTWoKIWreTgda8s_zTA&submissionId=5469b90d-43d8-5816-17fa-a8b4369ebb1d  (click the spiral galaxy photo to get past the verification)

 

https://manadopost.jawapos.com/berita-utama/09/01/2021/ada-fam-mamahit-ini-daftar-nama-diduga-kru-dan-penumpang-sriwijaya-air-yang-hilang-kontak/

 

 

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I think there has been an uncontained engine failure. That's pretty unusual but not impossible. They were  held up for departure due weather. You could get hail at relatively low altitudes. I'm sure hail can bring a plane down but it's just a guess.  Maybe the engines had sat for a long while  and not  been motored. Nev

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I'm going out on a limb here, and hazarding a mildly educated guess. The pilot is an ex-IAF fighter pilot. Not a real good choice to convert to an ATPL holder.

 

He's been taught to respond fast, and with maximum control deflections, to throw his fighter out of harms way from incoming missiles and ground fire. These blokes are noted for their heavy-handed inputs on aircraft controls.

 

I see a similarity to the American Airlines 587 crash here, where heavy-footed rudder inputs by the co-pilot, tore the vertical stabiliser off the Airbus. The pilots claimed they weren't taught to go easy on the rudder inputs.

 

This B737-500 is nearly 27 yrs old. It's been through several owners. It's done a huge amount of short trips in Indonesia, from island to island, resulting in high cycle times. The airframe total hrs would be pretty high.

 

I see a situation where a fighter-trained pilot at the controls, got pretty heavy-handed with the control inputs, in a high-hour, high-cycle-time B737, trying to avoid a storm cell, or lightning - at a speed that was possibly over maximum Va or Vb.

 

The result was catastrophic airframe failure, or major control component failure, that led to an immediate, uncontrollable dive into the Java Sea. This is pure conjecture, I await the examination of the CVR and FDR with interest.

 

The uncontained engine failure is also a potential event causing the crash. But these turbines are exceptionally reliable, and unless the last engine repair was done by the Indonesians, I'd have to opine it's a low possibility.

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Maybe a catastrophic engine failure causing loss of a wing?  An ordinary engine failure would not cause such rapid descent?

 

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An Asian aviation analyst has brought up a good point. With COVID-19 dramatically affecting airlines, the likes of Sriwijaya Air, in line with all airlines, have downsized dramatically - cut the number of staff in every dept - from pilots to technicians to ground staff - and tried to save money in every possible manner. 

 

The investigation will need to examine whether these desperate cost-saving measures might have impacted on the airworthiness of this particular aircraft.

It's entirely possible it flew with some inoperative instruments, maybe secondhand parts were used, perhaps even manufacturers operational time limits were being ignored, in the drive to not spend money.

 

I can recall one aviation analyst saying there will be an increase in aviation accidents as stored aircraft are returned to service, after months or even years of storage.

However, he failed to mention the impact of current desperate money-saving measures, that might impact on air safety and airworthiness, as airlines desperately try to stay afloat in these troubling times.

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1 hour ago, onetrack said:

he failed to mention the impact of current desperate money-saving measures, that might impact on air safety and airworthiness

Thank (insert your favorite deity here) that these cost-saving measures haven't impacted our beloved Alan Joyce. 

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None of these planes are helped by being  idle. It's certainly not just a matter of kicking it in the guts and revving it a few times.   This is a disaster for these Airlines and who they might have been leased from, in some cases.  Nev

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There's talk on the wrinkled fruit forum about an LAE claiming there's been an engine shutdown problem with corrosion in the engine bleed air, 5th stage check valve - that is exacerbated with aircraft storage.

 

The FAA knows about it, and has released a directive to check the check valve after 7 consecutive days or more of storage. There are also reports of check valve corrosion with anti-microbial additives and water in the fuel.

 

However, not even a double engine shutdown has the ability to cause such a rapid deviation from controlled flight, as this aircraft has done. And this aircraft has been operating steadily and regularly.

 

The CFM56 series is touted as one of the most reliable engines available, with GE-Snecma claiming, way back in 2003, that they had engines still operating with original components at 40,000 hrs.

 

https://www.aerotime.aero/25507-faa-ead-737-bleed-air-valve-corrosion

 

https://www.smartcockpit.com/docs/CFM_Flight_Ops_Support_B737.pdf

 

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The ocean depth is reported as 23M at the general area of impact - and the underwater vision I have seen from the divers appears to show a fairly sandy bottom.

 

But the bottom line is, the aircraft will be in ten thousand pieces with a vertical dive into the ocean at what appears to be well over 400Kts.

 

To add to that, the major parts of the aircraft will also be buried in the ocean floor, because they still would have been carrying major velocity, even after travelling through 23M of seawater.

 

One of the fisherman nearby reported a large wave of over 2M in height nearly swamping his fishing boat - and I'm guessing he would've possibly been up to a kilometre from the impact zone.

 

That's energy dissipation equivalent to the underwater detonation of multiple tens of tonnes of high explosive. I doubt whether the recovery teams will find many large major components.

 

You only have to see the engine core that they recovered, it's probably going to be one of the largest parts recovered.

 

There's an interesting crash report involving a Sriwijaya Air B737-200 in 2008. They landed at excessive speed with a failing/failed hydraulic system, and overran the runway, and wrote the aircraft off.

 

The only fatalities were 2 farmers they hit on the ground. Handling of post-crash procedures was exceptionally poor, and there was a serious lack of leadership from the flight crew.

 

The deficient actions of the Captain and F.O. showed extremely poor handling of the hydraulic failure, failure to consult the QRH, failure to carry out a go-around, and a failure to understand the aircraft operating systems.

 

I would not be in the least surprised, to learn that a similar series of events happened in this crash.

 

http://avherald.com/h?article=40bce6aa/0002

 

 

 

Edited by onetrack
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Reports from earlier today said the Indonesians were having "technical problems" with their ping-locating equipment, and were expecting a replacement locator to arrive from Singapore.

 

https://www.rnz.co.nz/news/world/434415/sriwijaya-air-crash-indonesia-s-black-box-locator-damaged

 

Regardless, the search went on, with a reported 3600 personnel on the scene, with 13 helicopters, 54 large ships, and 20 small craft.

Later this afternoon, it was reported that one of the recorders had been found and raised, and sent to Jakarta.

A press conference has just been held, and Indonesia's military chief Hadi Tjahjanto has stated the FDR has been recovered, and he is confident the CVR will also be recovered soon.

 

https://www.reuters.com/article/indonesia-crash/update-1-indonesia-says-crashed-sriwijaya-air-jet-had-passed-airworthiness-check-idUSL1N2JN08I

 

https://www.channelnewsasia.com/news/asia/sriwijaya-air-crash-divers-recover-black-box-indonesia-search-13943970

 

 

 

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There is a remote possibility that this accident was caused by a runaway trim event. No mcas in a 737-500 but trim cut out switch(s) are fitted because electrical gremlins can occur in any aircraft with electric trim. Here is an example   https://www.atsb.gov.au/publications/investigation_reports/2019/aair/ao-2019-019/

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There was extensive discussion and tests done during the Max issues surrounding runaway trim. There is a procedure for dealing with it but pilots found that once it had occurred turning the manual trim wheels required herculean effort & even with both pilots trying to turn them it took too long and the aircraft would likely have crashed. There were videos produced of this at the time. I'll have a hunt for them.

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