Far Beakon looks, of Northern. Sergey Amelin took a trip to it, 2 hrs ago, and took pictures.

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Below, the doggie, by the marker anthennae, so he didn't climb over the fence :o)

Old Time,


I can understand your concern for conjecture but quite frankly, I am sure many of the newbies are equally concerned at the quality of information coming from professionals.

For instance, isnt it clear that this control tower uses a military radar system to guide planes in during low visibility approaches? If so, why all the comments on guidance systems that could not have been used.

Also, I have asked twice for comments on the lack of broken turbine components given the crushed housing on the port engine - the only comments were pedantic ones, criticizing the terminology that was used.
Well, was the engine under power when it hit the ground or not?

Finally, it is very apparent that visibility was 400 meters or more - thus, how could the crew not see the ground for several miles during the approach - just as the AC was witnessed from the ground.

Thus, in the absence of the experts to determine (in general) what happened, there is nothing else to do but offer conjecture.

BMP, there's a difference between horizontal and vertical visibilty, some people wrongly assume that with such a visibility you'll see ground from a height of 400m. 400m is nothing when you're flying such an a/c, especially in a nose up attitude.

It was officially announced that according to CVR and FDR engines were working correctly - we can either accuse commision of lying, or accept their statement.

@ BMP
Mike already explained turbine problem
http://www.pprune.org/5653302-post887.html
visible part is stationary , actual turbine is behind

BMP

First, welcome to pprune!

Now... please take what I'm going to say in the spirit I intend -- which is to be helpful.

It's important to understand the purpose of the different threads and fora. This one (R&N) is intended for professionals to discuss aviation issues and events. So, for instance, the questions you posed above would not be asked (either because they’ve already been discussed, or they aren’t relevant in the minds of the professionals). If a “non-aviation professional” has a question, there are several fora and threads on pprune for that purpose.

I’m sure you understand the reason for this: If I were to show up on a surgeon’s medical forum, for instance, and start asking questions about why certain equipment or procedures are used, it would rightfully be frustrating for the surgeons on the forum. They are participating on that forum to discuss issues of interest to them at their level. Of course it may be interesting for others to read what’s there but the surgeons (in my example) are not signed on and participating on that thread to explain things to lay people.

In the case of the three questions you’ve posed above, you’ll find that all of them have already been answered (if you read the whole thread). Additionally, in the case of the military radar availability, no, it’s not “clear that this control tower uses a military radar system” as you mention. And even if they did, an aircraft such as this one had its own onboard capabilities that are more precise in terms of position information and assistance than most ground radars. This is an example of a question that you should pose on “spectators balcony” or a similar forum. Any such questions you have will (hopefully) be answered in a polite and helpful manner. (Whereas here on R&N that may not be the case because, as I say, the professionals get somewhat tired of lay people taking up time and space with items that are simply distractions to the professional discussion.)

I for one (and many others) will gladly attempt to answer any questions you might pose, but please try to do so on the correct area of the site. Or feel free to PM me if any of the answers you find are not clear.

Again, welcome to prrune.

grizz

Thanks - now I understand -I did not realize that the stator is in front on this design.

"If I were to show up on a surgeon’s medical forum, for instance, and start asking questions about why certain equipment or procedures are used, it would rightfully be frustrating for the surgeons on the forum."

Grizzled,

Were the surgeons discussing an operatin that was progressing without a hitch, your analogy is absolutely correct. However, the discussion here betray's no such confidence level.

I dont mean that as an offense to anyone here as I personally believe that this incident has been hampered by lots of disinformation, unintentional or otherwise. I stand corrected on the stator - I did not realize the stator was in front but for on other issues, there still seems to be not much discussion on critical issues. For instance, given a glide path of 3 deg, 400 meters of visibility means being able to observe the ground for several miles before impact.

I think in the absence of an "official" explanation, it it incumbant on the pros to crystallize the issues to determine the ultimate reasons for this failure. I think the discussion needs to focus on what several things might explain how this AC wound up too low and too soon.

Same thing as grizzled mentioned again. 400m visibility means 400m horizontal visibility. And that is at GND level. In fog as higher you are you have less horizontal visibility. You might have visibility straight to the GND, but horizontal in the approach you have as good as nil forward visibility.

Hi all
From what was mentioned before and above , there's nothing to talk about for now .
Not until we get some more facts.
My summary ( please have mercy if I'm wrong ) :
There was a fog . If there wasn't they wouldn't crash.
Pilot was familiar with that airport.
He was flayng there once and sometimes twice a year ( as second )
They were flying blind , by instruments.
Probably there's no need to mention that from obvious reasons they couldn't look down , only forward and to the sides ( view from cocpit :} )
That's about dispiute about visibility , they could see nothing even when ac was visible from the ground .
They didn't realize their altitiude for some unknown so far reason.
Pilot was trying to pull up , when he could see the ground .
Unfortunatelly it was too late , sad thing is , that he was short only about 3 meters to make it :sad:
Only question is , why they were wrong with altitude , and why they had no warning from control tower.
Pilot was speaking russian .
I'm about same age as RIP pilot , and russian language was very important in primary school.
It was still communism back then.
Didn't use russian since then , but I remember numbers , and can speak a little (after 20 years)
And pilot was flying to russia , piloting russian plane ( probably tonns of manuals in russian) , and in published interview with ATC he mentioned that they couldn't understand numbers :confused:
I hope on wednesday we will know a bit more .

I understand my newbie deficiencies :o), but will also add that from 2009 it became more difficult to fly to Northern for the Polish crews.
Say, two flights in 2009, one with Polish PM in 2010 = 3 max.
Until 2009 they were renting their navigator for flights to Northern from Russia, then cancelled the service. It could be that the three following flights were without fog.:sad:

Hubert,

The pilot was fluent in Russian and was familiar with the airport having flown a test run the week prior and having flown there during prior year Katyn commemorations.

Polish Crash Probe Points to Human Error - WSJ.com

I know
that's what I've written above

On the last flight before crash they were landing the opposite direction.

NDB there is on 4km.

Niestandardowy rozk?ad radiolatarni zmyli? pilota Tu-154?- Onet.pl - Wiadomo?ci -26.04.2010

GPS DOP
 

My professional background is in the development of navigation systems and I tried to compute the Dilution of Precision (DOP) for current GPS constellation, crash location and time. It is interesting that there is a short period of bad DOP that agrees with the time of the crash. It means that the performance of standard GPS positioning was worse than usual at that time.

http://athena.fsv.cvut.cz/%7Emervart/dop.png

P.S. I apologize for posting this and not being a professional pilot (just a private one)

Mervart,

Thank you for a valuable new point.

:ok:

That's scientific approach! Where is that short bad period, on the chart?
(I'm sorry. If that's possible to explain to outsiders, at all)

I did some research and according to the type certificate the NDB approach minima for the newer Tu-204 are 100 by 1500 m. For the 154 I've seen figures something like 120 by 1800 m. It is obvious the actual visibility conditions were nowhere near what's required.

So it sounds like this whole thing was a bad bad idea. It would be miracle if they didn't crash.

mervart,
very interesting, but, as we know, the crash was at 10:40 but Russian time. If I'm not mistaken, it would mean 7:40 UTC, when, according to your calculations DOP was around 2.
Could you also calculate VDOP?

Tu-154M minima data

minima-Tu-154M.jpg | arrakis | Fotki, Zdj?cia, Obrazki Fotosik.pl

Arrakis

It was 6:40 UTC

You are right. Moscow is +4 now. It means DOP between 2-2.5.

Arrakis