Weather
 

Pic of aircraft on ground in Sochi shows wet snow. Anyone have the METAR for that night? De icing issue?

The final position gave us a new stone to mosaic:

The plane flew for ca. 10-11 km before crash - investigators told 6km south, then U turn and 4km north. They also told that the speed was approx. 350km/h and that there was lack of climb. It is not clear what exactly they meant by this lack of climb. Anyway, ATC lady instruct the crew to call Sochi approach after reaching 300m. They never did it. Investigators (not Kremlin) also supposed that it was technical issue and/or human error.

It looks that the key information is climb rate from airport radar data. If they found that climb rate was very low, they could exclude some reason, for example bomb.

Back door:
URSS 250230Z 06004MPS 9999 BKN033 OVC083 05/01 Q1019 R06/090070 R02/090070 NOSIG
RMK R02/05004MPS MT OBSC QFE763


Decoded:
Location...........: URSS
Day of month.......: 25
Time...............: 02:30 UTC
Wind...............: true direction = 060 degrees; speed = 4 m/s
Visibility.........: 10 km or more
Cloud coverage.....: broken (5 to 7 oktas) at 3300 feet above aerodrome level
Cloud coverage.....: overcast (8 oktas) at 8300 feet above aerodrome level
Temperature........: 05 degrees Celsius
Dewpoint...........: 01 degrees Celsius
QNH (msl pressure).: 1019 hPa
Next 2 hours.......: no significant changes

Well, official press-release already published stating that is was no military cargo on board. They said it was only luggage plus 150 kg of medical supply and food.

The "beach camera" pictures, I spent some time looking at google maps, the Imray nautical charts etc and I am fairly confident that the low green light shown on the video is at the end of the harbour wall on the Sochi Yacht Club, it is the only likely candidate. If you plot a line roughly looking up the beach at the angle shown in the video, then the light that appears in the sky briefly is in the correct alignment for the light on the harbour wall at the Port Of Sochi, which is elevated on a tower. The shape of the light and the distinct on/off is consistent with a nautical light rather than an explosion.

Pure speculation on my part: Possible misuse or lack of use of the engine anti icing systems? Potential freezing of tat probes in the engine inlets, leading to erroneous thrust settings and then resulting confusion. Might explain the lack of climb, as the crew may have reduced thrust to prevent an indicated overboost, which then led to an unrecoverable stall...

From historical perspectives Air Florida and the DC8 at Gander come to mind.

One can take off but not climb.

I'm not sure if it matches the other cold weather event of Continental at Denver. I'm quite sure that the TU has lots of experience in cold weather but perhaps some history might pop up on this board

Does it have slats for takeoff to increase its tolerance to wing icing?? or does the weather at Sochi preclude any discussion in this?

Not quite the full story. I flew with a captain who had 10,000 hours on Tu-154s. Although he liked the tough airframe, it required yaw-dampers, pitch-dampers, and roll-dampers to keep it flying (a by-product of anhedral and other idiosyncratic designs). They had to practice damper off flying in the real aircraft, and he said it was utterly uncontrolable. You might get away with a visual, but could not follow an ILS.

In fact, Tu-154 damper off flying is somewhat reminiscent of that Liveleak video in comment #68. Great video, I have to say. Would hate to think what that looked and felt like, in the cockpit ! Good airmanship to fly it around a bit, and get a feel of the instability, before landing.

Operation near freezing temps is not unknown for ru operators. So I would assume a more sudden event. With the relative light TOW they should be able to climb on two engines.

@paperHanger my nephew (also a pilot, russian-born wife) is very familiar with the area and concurs with your suspicion.

Weather then was about -4 C with moderate snowing. Here in Sochi it was +8 C at takeoff, no precipitation at all, not very comparable weather scenarios.

Actually - cold temperature, by itself, helps with both - takeoff and climbing.

The media found another witness who was allegedly out on a boat and described the plane descending as if trying a water landing. The forward speed was slow and it was in an "unnatural" nose up position. It hit tail first which broke off and quickly sank.

Deep stall perhaps?

@unworry ... also, the crash site is South-East of Sochi ... the webcam footage, if it is from Sochi Beach, is looking North West ... 180 degrees away from the crash site ..

@vovachan if it had come in slow and nose up, it is unlikey to have broken up ... the TU154 is very solid bit of kit, a slow water landing would have been very survivable, at least a few passengers would have managed to get lifejackets on even if the tail broke off, in front of the rear bulkhead. The fact that no one survived and the authorities insist no one had a life jacket deployed would suggest it either broke up mid air, or entered the water at some reasonably high velocity.

Perhaps you forget AF447. That hit the water at a forward speed of 107 knots and nose-up pitch of 16.2 degrees. It was not "very survivable". Had we seen it, I think we'd have thought it to have a low forward speed and to be in an unnatural nose up position.

IF the eyewitness report is a cousin of the truth, I think Oakape's suggestion of deep stall has merit. Of course eyewitness reports may be correct, far off the mark, or anywhere between

Not sure that in the realities of present-day Russia it's practical to separate the two. Thankfully tho it's hard to control all info these days from one central source of political power. Even it being the Kremlin.
Anyway thank you for you concise and clear postings in this thread.

BTW it's reported that the BLACK BOX IS FOUND. ????: ???????????? - ????????: ????????? ?????? ???? ??-154 ? ???? ???? ???????? (in Russian)
A source told TASS state news agency that 1 of the flight recorders has been located, yet to be lifted. It doesn't specify which one it is, and says it's currently unknown how badly it was damaged. However it does state that it was found "under the plane's cockpit" adding that the other *two* are believed to be in the tail part.

Lack of climb could be an instrumentation problem.
Does anyone know if this was a 'steam gauge' type aircraft?
Were the vertical references actual spinning gyros?

Vertical speed makes a world of difference.

No, radar readings from a ground station.

Flight data recorder has been recovered

Russian plane crash: First black box located in the sea - BBC News