flash
 

Or bright aileron strobe? they show a couple of times before that anyway (1st as a camera reflection).

Anyway, would vertical rudder / yaw problems a la flash airlines possible cause this nose-dive?

I'm not so sure about that.

Go-around, TOGA power, counter the pitch up, inattention to attitude, huge pitch-up, grab thrust levers back to aid pitch down, stall (Or minor variations on that theme) would do it. Classic 737 pitch-couple trap.

We have at last an unquestionable document of that fantastic ball of fire witnesses claim to have seen just before impact in almost all aviation accidents.
According to my humble opinion, because:
1) It is easy to estimate that the aircraft had an absurd attitude of c.ca -90° in the last few seconds of flight.
2) At 00:05 video time a strong lightning, likely a sign of an explosion, is clearly visible.
3) Two major political figures were on board
I seriously suspect tha it was a terrorist attack.
I'll be happy to be contradicted

The security video does look disturbingly reminiscent of the NTSB recreations of the US 737 rudder hard-over incidents though...

Board Meeting Animations - Uncontrolled Descent and Collision with Terrain USAir Flight 427 Boeing 737-300, N513AU, Near Aliquippa, Pennsylvania, September 8, 1994

DOVES:

Regarding your point 2, no the flash at 4s is not an explosion. As someone pointed out already it is just a strobe light on the plane. You can see a previous flash at 2s into the video, reflected from the ground.

I'm sure someone might know the 737 strobe interval, but 2s is about right compared to this video:
Any explosion is not going to be so brief (single frame) even at the low frame rate of the video.

VFD:
even if you were to roll inverted and suddenly pull back on the yoke do a splits-s it would be hard for 73 to get into that attitude below 1000' unless the aircraft were to enter the initial stages of a spin ( incipient spin ) or some sort of catastrophic structural failure..

If the video being shown is the correct video showing the actual accident, no reason to believe it is not, it reminds me of the old rudder hard over accidents involving 737s years ago.

The two I remember the best was the one at Colorado Springs and the one at Pittsburgh (I think) as I flew over both accident sites.

The rudder hard over caused accidents were near vertical impacts.

I thought that Boeing had fixed that problem. Something to think about anyway and I'm not saying that is the cause of this accident.

The rudder hard over caused accidents were near vertical impacts.

So did SE go rounds with no rudder: lets' wait and see then add wise contributions instead of speculations. The FDR should be quite modern; CVR also.

BBC talking about vertical landing and journalist talking about vibrations when landing at Moscow on previous leg. Crap concrete runways do tend to give some vibration on landing. Vertical landing suggests it was a bloody helicopter not fixed wing. I do wish the instant expert reggie spotters would STFU and let the pro's get on with the real job of finding out what really happened. Uninformed speculation does not help. Just think that there are thousands of other 737 crews and passengers out there flying the same aircraft
Rant over.

OK, I'm not a flying expert, however I know enough about aerodynamics and the outline capabilities of a B737-sized aircraft.
Given that this aircraft was initiating a GA went everything went really pear-shaped (following the unstable approach that is), then how the dickens does it end with such a high (apparently from the brief video) almost 90deg nose dive into the ground?? I mean, I wouldn't expect that it could be achieved by anything other than an astonishingly savage pull up, to near vertical climb to stall, wing over and dive....especially to remain anywhere near the vicinity of the airport security cameras?

edit: .....or stall, tumble and dive?

video by security camera
 

AS FAR AS I CAN SEE THAT A NOSE DIVE!!!!

As far as I can gather from this footage, the aircraft is in a steep dive, and wings in a steep angle of bank...

From the motion of the security camera it's clear that the wind was howling even near the ground. Likely a go-around handling mistake.

I agree one hundred percent, that is why I posted this;

Never the less, by studying past similar accidents we can sometimes solve new accidents if there are similar patterns/events. I know, been to the school, read the books, watched the films, took the tests and passed them.

If I was assigned to this accident, the rudder issue would be one of the first things looked at, if for no other reason than to dismiss it as a cause as soon as possible.

I'm sure we will hear the probable cause sooner or later, hopefully.

What bank? All I see (after several pause/rewinds) is a level nose-dive.....tail square-on to camera? Have I missed something?

At 90 degrees nose down, bank angle is pretty irrelevant.

Me too, bank would also result in some kind of rolling during the dive.

To me it looks like the stabilizer suddenly let go his downward force, due to whatever reason (separation? tail stall?).
I find it hard to come up with another scenario which would result in such a sudden dive.

While it obviously doesn't happen every day, it is a notorious characterisitic of aircraft with under-wing (below center of gravity) thrust lines to pitch up significantly if TOGA power is applied. It has happened before (fortunately, usually with prompt corrective action from the crew). c.f. TAROM Flight 381, 1994, Paris-Orly.

Extended lift devices (slats, flaps) can exacerbate the pitch-up tendency.

The 747 at Bagram managed to take off, climb, stall and crash within the airport boundaries. Given that a go-around likely began well before reaching the runway threshold, I don't see why a 737 could not end up with the same results well within the airport boundaries.

I'm not saying that that is what happened in Kazan - I'm just pointing out that it is well within the realms of possibility.

One other factor I haven't seen noted yet is that Kazan is undergoing major reconstruction, with one large runway partially built, and the other perhaps a former taxiway being used as a runway (cf Google maps).

No reason this would lead to a crash directly - but the airport layout (combined with weather/visibility problems) could have contributed to confusion and the need for a go-around or multiple go-arounds (whichever turns out to be the fact.)

Good to know however personal experiences go only so far. Russia (and the area of the former USSR) still has triple the aircraft accident rate compared with the rest of the world. And like the 2008 crash of another Boeing 737 in Russia (also landing) at Perm can show a breath-taking level of incompetence among the crew. But I full agree about the MAK - very competent accident investigation team.

The airport in question had 2 parallel runways. One is currently being converted into a taxiway, that's the reason for the construction equipment