https://www.ctvnews.ca/world/indonesia-jet-carrying-62-goes-missing-on-domestic-flight-1.5260216

Not good. Flightradar24.com said the aircraft had lost more than 3,000m (10,000ft) in altitude in less than a minute.

Route: Jakarta to Pontianak
Callsign: SJY182
Aircraft: Boeing 737-500, PK-CLC
Take off: 07:36 UTC
Highest altitude: 10,900 feet
Last altitude: 250 feet
Signal lost: 07:40 UTC

 

Edited January 9, 20215 yr by CYXR

I flew in and out of Jakarta in 2019. I departed from the oldest terminal, very beautiful gardens surrounding the building, and a very nice feeling of being in Indonesia. I loved CGK airport, and I will never forget the warmth and hospitality I experienced while I was in Indonesia. My deepest condolences to all those who lost loved ones there today.

There has to have been a catastrophic failure of the aircraft’s structure for it to have fallen so quickly. Given the age of the aircraft maybe a tail / rudder separation similar to the American Airlines A300 back in November 2001 south of JFK.

Edited January 9, 20215 yr by Ray Proudfoot
Aircraft type corrected

15 minutes ago, Ray Proudfoot said:

There has to have been a catastrophic failure of the aircraft’s structure for it to have fallen so quickly. Given the age of the aircraft maybe a tail / rudder separation similar to the American Airlines Boeing back in November 2001 south of JFK.

Hi,

 

I have to correct you on that one sir. That was an A300, the pilot used too much of an input on that rudder. It caused imminent structural failure to the rudder, making it seperate from the plane.

Not good indeed. The 737-500 stands for good reliability, even when they're aged. Perhaps cutting costs on maintenance could be a suspect in this matter.

 

Kind regards,

 

Peter

 

1 minute ago, Piotr007 said:

Hi,

I have to correct you on that one sir. That was an A300, the pilot used too much of an input on that rudder. It caused imminent structural failure to the rudder, making it seperate from the plane.

Not good indeed. The 737-500 stands for good reliability, even when they're aged. Perhaps cutting costs on maintenance could be a suspect in this matter.

Kind regards,

Peter

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.

It appears that condolences are to be made. If all survived with or without a serviceable aircraft then I suppose the world would have known by now. 

Interesting trace on FR 24 picture in the linked article  - if the projected course was the black line then why the bit of a dogleg turn just prior to the trace being lost? Weaving around some bad weather perhaps?

Mark, what sort of bad weather could cause an aircraft to fall out of the sky like that? I know of only three reasons and I mentioned one in my earlier post. A missile strike seems highly unlikely which leaves terrorism which again, seems unlikely.

No emergency radio transmission could very well mean an explosive device on-board (?) 

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

The aircraft went from 10600 feet to 1400 feet within just 21 seconds which would be an average descent rate of about 26300 feet/minute. What's more is that the airspeed dropped significantly from 284 knots at 10600 feet to as low as about 120 knots at about 6000 feet before rapidly increasing again to 358 knots at impact (all ground speed). This graph is zoomed in so the profile is easier to see (can't embed):

https://pbs.twimg.com/media/ErS_fiiXIAEwjTq?format=jpg&name=4096x4096

Residents in boats out on the sea allegedly heard two explosions before finding debris floating in the water.

Without speculating too much, I wonder if they encountered a stall for some reason given the speed and altitude profile during the dive and/or a microburst. Thunderstorms were reported and there was a large cell near the flight path. The right turn at the end could have possibly been an attempt to return back to the airport.

WIII 090800Z 28008KT 4000 -RA BKN016 OVC018 26/24 Q1006 NOSIG=
WIII 090730Z 30006KT 5000 -RA FEW017CB OVC018 25/24 Q1006 NOSIG=

Edited January 9, 20215 yr by threegreen

I was thinking of Birgenair 301. Faulty airspeed indications, pilot error, then stall as a remote possibility. Time will tell, but I think it's totally natural for aviation enthusiasts like us here to throw theories around and perhaps eliminate them one by one. Even though that's what NTSB equivalent people are doing anyway. I'm going to read a bit about the American A300 at JFK now. I somehow can't comprehend that bit about the rudder imputs being a problem, but indeed I remember it was the primary finding. I vaguely remember a United 747 out of SFO bound for Australia had encountered a near crash, something to do with improper rudder use as well.

Antipodes, the A300 accident was caused by the rudder being moved from extreme left to extreme right repeatedly. A bolt was severed by that action causing the tail assembly to detach.

Stalling at 10,000ft seems a remote possibility. That could only happen if the pitot tubes were blocked causing faulty air speed readings. At that latitude it seems unlikely ice could have formed.

I suppose pilot action cannot be ruled out but that seems the least likely.

@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.

I just skimmed over the info about American 587, yes, such drastic, rapid and repeated full left and full right rudder inputs, unfortunately catastrophic. United 863, the 747 out of SFO, apparently not using any rudder correction, which was inappropriate for their situation. That was maybe unrelated to this situation. Birgenair 301, most likely had a wasp nest in a pitot tube.

21 minutes ago, Antipodeslonghaul said:

I'm going to read a bit about the American A300 at JFK now. I somehow can't comprehend that bit about the rudder inputs being a problem, but indeed I remember it was the primary finding.

There are two things which can detach a tailplane caused by rudder inputs: One is if you give the rudder a big deflection whilst at high speed, which will put a large amount of sideways force on the tailplane and that can potentially lever it off. This is something to be aware of with all aeroplanes when they are at speed. The other (which was the case with that A300 over Queens), is if you repeatedly kick the rudder from side to side with a fair amount of speed on, this causes a what would normally be an acceptable sideways force to become considerably more damaging as the pressure on the retaining bolts is rapidly alternated one way to the other.

Effectively it is the same as when you bend something such as a twig backwards and forwards quickly, in order to snap it. You could probably bend it one way much further without breaking it, but rapidly bending it back and forth will usually break it. That's what caused the bolts, which were holding that A300's tail on, to snap despite each individual amount of sideways pressure theoretically being within their limit. After the tail broke off, it was essentially uncontrollable.

The pilot who made those inputs had been trained to aggressively counter wake turbulence as an airline policy, and the aeroplane possibly did fly through some wake turbulence although it is thought it would only have lasted a second or two before it was clear of it, but the pilot's records indicated that he was inclined to over-react to such things and it seems this may have been the case in that accident unfortunately.

5 minutes ago, Chock said:

.......

The pilot who made those inputs had been trained to aggressively counter wake turbulence as an airline policy, and the aeroplane possibly did fly through some wake turbulence although it is thought it would only have lasted a second or two before it was clear of it, but the pilot's records indicated that he was inclined to over-react to such things and it seems this may have been the case in that accident unfortunately.

Absolutely. I Iike the analogy with bending the twig back and forth.