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An-148 missing after takeoff from Moscow

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An-148 missing after takeoff from Moscow

Old 13th Feb 2018, 05:21
  #101 (permalink)  
 
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Both recorders are now lifted and seems they are in satisfactory condition. Hope first information from FDR will be available in a week.
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Old 13th Feb 2018, 06:40
  #102 (permalink)  
 
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Better angle showing the vertical excursions described by Rob and the impact point identified by Kulverstukas:

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Old 13th Feb 2018, 07:51
  #103 (permalink)  
 
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The initial upset where climbing becomes a descent looks very sudden. There must have been a rapid change of pitch.
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Old 13th Feb 2018, 08:10
  #104 (permalink)  
 
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More interesting than the vertical excursions is the absolutely straight track the aircraft flew. Does not look like a hand flown plane struggling to maintain control... If there would be an elevator issue, the autopilot would most probably quit, and the track would not be that straight. Either strange data or a strange behaviour...
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Old 13th Feb 2018, 08:36
  #105 (permalink)  
 
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It would be interesting to know what the departure clearance was in regard to altitude. Afaik altitude in Russia is not in feet but in meters below transition altitude. The first dip on the graphics looks like the pilots following an atc command like "descend to 2000m" or similar (2000m aprox. 6700ft) and then later a clearance for higher. Just a vague possibility. What's strange is that the rapid descent thereafter was absolutely straight which would suggest that the plane was at least partially under AP control.
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Old 13th Feb 2018, 09:38
  #106 (permalink)  
 
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What's strange is that the rapid descent thereafter was absolutely straight which would suggest that the plane was at least partially under AP control.
What would the ballistic trajectory look like ?
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Old 13th Feb 2018, 10:04
  #107 (permalink)  
 
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MAK/IAC proceeded to decrypt the data of the An-148 FDR

"Due to mechanical damages of the protected memory modules, it was necessary to conduct their complete disassembly with the dismantling of solid-state storage media," the report says on the IAC website.
IAC specialists successfully copied all the information of the on-board parametric recorder. Now at the disposal of the IAC there is a record of 16 flights, including the one that ended in a catastrophe. The specialists began to decipher the record.
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Old 13th Feb 2018, 10:43
  #108 (permalink)  
 
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Originally Posted by Jetjock330 View Post
I am thinking blocked pitot, and increase in indicated speed with altitude, thrust perhaps coming to idle (auto throttle if it has) and stall.
Perhaps you mean all statics?
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Old 13th Feb 2018, 10:48
  #109 (permalink)  
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The sudden decent may be causal rather than the result of a failure.

Not VFR I gather, but some stimulus other than ATC. For example, suddenly/instinctively pushing against the autopilot only to find pitch control was far from normal after that.
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Old 13th Feb 2018, 11:17
  #110 (permalink)  
 
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Don't put much on someone else in the cockpit - they normally carry one or two ground engineers to sign the transit check (wonders of all Antonov planes), it is quit likely that mechanics are jumpseating in cockpit especially with high pax loads.
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Old 13th Feb 2018, 11:37
  #111 (permalink)  
 
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From the bare metal leading edge of the horizontal stabilizer I would assume, it has a bleed air anti-ice system. Can somebody confirm the ice protection system design? Is the AoA Vane/pitot/static heating monitored/indicated? Is the elevator hydraulically actuated? The pure elevator related flight path fluctuations in combination with a straight track indicates to me that the issue was somehow related to pitch control, either due to the auto pilot, the FWB or mechanical/aerodynamical horizontal stabilizer/elevator issues without proper feedback to the systems/pilots.
I would assume the autopilot would quit if the pilot fights against it or some system malfunctions.
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Old 13th Feb 2018, 11:51
  #112 (permalink)  
 
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I'm probably being slow here but if the aircraft was intact when it impacted the ground and then broke up into a lot of very wide-spread pieces, why isn't there a big black hole in the snow?

Specifically, I very much thought it looked like an in-flight break up because of how wide-spread the wreckage was and I'm having a hard time getting my head around the type of ground impact that would leave this sort of mess, as opposed to say a shallower version of the crater from the West Air Sweden CRJ crash in 2016?
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Old 13th Feb 2018, 12:24
  #113 (permalink)  
 
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Originally Posted by andrasz View Post
In an inflight breakup one would typically expect to find pieces well before the main wreckage (hence my questions to locaton). In this case it seems to be confirmed that all the pieces we saw initially are within the debris fan ejected from the main impact point.
Well exactly, ALL we have seen so far.
There may well be elevators or other control surfaces back along the track. I'm sure its not easy to find parts in the snow.
It was clearly mostly intact at the end, but not necessarily 100%
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Old 13th Feb 2018, 13:06
  #114 (permalink)  
 
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Russian media is quoting MAK (Russian AIB) says heating of pitots and static was off and caused wrong speed indication which lead to crash

Use google translate
https://m.lenta.ru/news/2018/02/13/mak/
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Old 13th Feb 2018, 13:22
  #115 (permalink)  
 
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Thats is a hell of a quick investigation....
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Old 13th Feb 2018, 13:30
  #116 (permalink)  
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English by RT

Here's a RT report in English:

The crash of An-148 passenger plane in the Moscow Region may have been caused by incorrect flight speed data due to icing, the Interstate Aviation Committee (IAC) said after deciphering the flight data recorder.

On Tuesday, the IAC announced it had completed the deciphering of information contained in the one of the black boxes – the on-board data flight recorder – of the crashed plane. It is still working on the other black box, the voice recorder.

The preliminary analysis suggests that the “incorrect data about flight speed on the pilots' indicators, which in turn was linked to the icing of the pitot-static [sensor] system” led to a “special situation” with the plane, according to the IAC statement.

(continued)
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Old 13th Feb 2018, 13:35
  #117 (permalink)  
 
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@akaSylvia
having a hard time getting my head around the type of ground impact that would leave this sort of mess
You would need more information to get a good answer of course... But one aspect that we could keep in mind is that it is a high wing with underslung engines. So the impact dynamics can be quite different.

One scenario might be that the final segment of the flight path was under a shallow angle and at some speed. Which might explain the impact 'channels' in the snow. The entry being such that the wing-engines combination detaches from the top of the fuselage. Which might explain the very unusual and high 'roll over' trajectory of 'long flames' on one of the videos. This detachment both rupturing the fuel tanks and destroying the structural integrity of the fuselage. Which might help explain a combination of fragmentation and deformation that could follow that ...

Even within such a single scenario there are multiple possible sub-options. Based on for example engine thrust at impact, impact angle, and impact speed.
If you look at the long flames, and assume we see the trajectory from the side, it might suggest that the planes was wings-level on impact.

The snow is at least knee deep and can hide quite a lot of information if you have to go by photos only.
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Old 13th Feb 2018, 14:36
  #118 (permalink)  
 
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Assuming they knew they had conflicting instrument indications (they might not have had time to deduce it was airspeed indication that was wrong) why wouldn't they fly power / attitude?

Surely they wouldn't just slavishly follow an erroneous ASI readout and ignore excessive pitch attitude indications (presumably on both main AIs and the standby AI)?
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Old 13th Feb 2018, 14:37
  #119 (permalink)  
 
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Originally Posted by akaSylvia View Post
why isn't there a big black hole in the snow?
It was snowing at the time of the accident.
So, a snow blanket has covered the wreckage.

Originally Posted by akaSylvia View Post
Specifically, I very much thought it looked like an in-flight break up because of how wide-spread the wreckage was and I'm having a hard time getting my head around the type of ground impact that would leave this sort of mess, as opposed to say a shallower version of the crater from the West Air Sweden CRJ crash in 2016?
Compare with the images of 5A-ONG wreckage in Lybia (although the Lybian plane speed was lower).
It was also a shallow angle impact.


https://reports.aviation-safety.net/...332_5A-ONG.pdf

Last edited by Luc Lion; 13th Feb 2018 at 14:47.
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Old 13th Feb 2018, 14:47
  #120 (permalink)  
 
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Thats is a hell of a quick investigation....
There is some reputation of the Russian Industry at stake...
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