Kulverstukas

May be PIC pushed "GO AROUND" button, but nothing happened? As I can understand, not everything recorded by FDR.

RetiredF4

@ Criss
Now you are considering my line of thinking.
Thanks.
franzl

criss

Partly - they still busted the minima (their minima was 100m above aerodrome, they descended to 100m AGL, and this time terrain below them was much lower than the aerodrome), and as this was a non-precision approach, they should have arrested the descent before reaching 100 (they shouldn't have descended even a bit below), and not just making a decision to go around at this point.

SadPole

Kulverstukas

There is almost a whole chapter in the report that deals with discarding that possibility. There was even a goaround being executed on Apr. 6, 2010 extracted from the Flight Data Recorder. See Page 150 (English). And yes, they claim that even when automatic GoAround is impossible the button activity would have been recorded. Makes sense - the FDR is for recording all actions regardless if they make sense or not.

Kulverstukas

SadPole so Wyborcha not read it.

SadPole

You can safely assume 95% of people who comment on it in political circles in Poland (even in media) have not read it.

Few of these people are proficient in foreign languages, fewer still in capacity that would allow them to read technical reports on their own, and the Polish translation was prepared for them only yesterday, I think.

So what did they do – they listened to the MAK conference and heard (what they see as) politically loaded conclusions. Then they discard it all and look for theories that would make them happy. (Trust me, you don’t want to know any more of these theories).

mbar

Yep, seems that they didn't read the report.

"Z uwag do raportu MAK i stenogramu wynika, że na wysokości 100 m prezydencki tupolew był 2400 m od progu pasa. I leciał na niej przez 8 sekund."

They still claim that the plane leveled off at 100 meters and flew horizontally for 8 seconds and we know it's not true.

After reading the article I have a feeling that Wyborcza might be trying to skew some facts. They are saying that new analysis of CVR revealed cpt Protasiuk saying "odchodzimy" (go-around) at exactly the same moment as first "pull-up" from TAWS. But the truth may be that this was a question directed to Blasik, like "odchodzimy?" (are we to go-around?). The only difference in Polish regarding statements and questions is the pronounciation of this single word. Delayed or no answer from Blasik (if that was a question) might have caused the following crew state of indecision -- but please note that this is my pure speculation. Unless I can (or we all can) hear it, we can only say "the truth is out there".

RetiredF4

absolutly correct. But the reason for doing so has been stated before:
- Using radar altimeter instead of barometric
- Late descent
- Therefore steep descent
- Therefore faster then normal
- No CRM at all
- marginal proficincy.

But intention to do it that stupid way with Autopilot down till impact?

franzl

Kulverstukas

SadPole, I read a lot of "theories", from liquid helium to false beacons to KGB agent onboard, who shoot Cpt and jumped with parashute

SadPole

mbar

Precisely. This is why I think in the era of the internet they should have just posted the recordings. If they did, I would extract the "PULL UP" sound out of that fragment and see it for myself. Software for doing that is available all around. Since "PULL UP" is a recorded voice, and it is repeated a few times, you can create a pure form of it and then subtract it from the critical fragment. This gives you whatever they are supposed to be saying at the same time.

But, I think the fact that they mention that it might not have been assertive enough would indicate that it was a question. If they can make the words out, they can make out the intonation. Unless we are dealing with some intimidated person, there is a hell of a difference between the way a command would be spoken and a question. And it is true in all languages:

GO AROUND!!!
Go Around??

UHOD!!!
Uhod??

Therefore, they still have not figured out that this is only the impression one would get by looking at the radio altimeter due to terrain falling at that time. That's the whole damn root of the problem.

See Figure 45 in the report.
Red line - Radio Altimeter readout.
Blue line - Altitude above RWY 26.

SadPole

Kulverstukas

I'm truly sorry.

janeczku

Since the polish media and some people in the forum are starting once again to consider A/C having stopped descend at 100m, i am diggin out my drawing of the vertical approach path which i posted last summer and which - amazingly - is still quite valid in the lights of the now available FDR data.

As this drawing was made matching CVR with terrain profile, lets match it with the FDR data this time.

First, we check out the FDR plot of the radar alitude:
Following a steep altitude decrease, the radar altitude levels in at around 100m between 10:40:42 and 10:40:49 with a 5 second jump from 100m to 109m and back.

Secondly, we look at the approach/terrain drawing:
The time between 10:40:42 and 10:40:49 is exactly the time when the aircraft overflew the slope of a 1km wide and ~40m deep dell.
Thus, even though the aircraft was still descending after the first 100m callout, the ground separation aka radar altitude naturally leveled in at ~100m for around 8 seconds until the deepest point of the terrain was reached.
As the terrain descended even steeper than the glidepath of the aircraft, the radar altitude shortly raised from 100m to 109m.

It is all clear!

On the other side, if the aircraft had in fact stopped to descend at 100m QFE, then - because of the descend in terrain - the FDR would have registered a steadily increasing radar altitude curve from 100m to 140m in between the 8 seconds in question.
But this is not the case!





Uploaded with ImageShack.us

For those interested: I found a nice vertical terrain profile of the approach path to smolensk airport here.

Alice025

criss @1043, very concise, on the importance of being at 100 metres in ? good shape.

SadPole

Janeczku

Yes, this was a very accurate estimate of the flight path based on the transcript alone. But, your chart assumes pretty consistent real descend rate. If I remember correctly, this was the main controversy at the time your chart was being discussed. If the descend rate was constant, then at least one of the ATC (on course, on path) calls would have been wrong. The descend rate was not constant – they INCREASED it most likely as a result of observing the falling slope of the ravine on Radio Altimeter. Meaning they did not even listen to the ATC but most likely tinkered with controls based on Radio Altimeter readouts alone. If the ATC says "on course, on path", why increase descend rate?

I remember that controversy, I even thought that maybe they unknowingly discovered some ground following mode in the ABSU that changed the descend rate for them based on RA. I even went at that time through the ABSU schematics to discard that possibility (yes – I'm nuts ).

See the fragment of the MAC/IAC Figure 45 I was talking about.
Red line – Radio Altimeter readout.
Blue line – Altitude above road nearby
Green line – ideal glidepath.

SadPole

Maybe, there is still hope. Finally, the media in Poland allowed some sane people to speak.
Interview with Polish Ambassador to Russia:



So, how do we expect the (insert expletive) to listen to the ATC or pilots if they did not listen to our own Ambassador even????

I guess, this could only mean that our ambassador must be a KGB agent. The official line from Warsaw today is that Russians did not want to provide the navigator (aka leader).

Kulverstukas

SadPole, if you have schematics of ABSU (АБСУ-154-3 AFAIK), can you check if FDR writes button signals regardless if button is active or not? I mean, if "GO-AROUND" btn was deactivated because of deactivated ILS, will it sent "pressed" signal or it is physically switched off by some relay?

SadPole

Kulverstukas

Upon examining the schematics, I see it actually might be a correct theory:

The automatic GoAround is initiated with the throttle levers in the position «Взлетный режим» (takeff) or by pressing GoAround with «Уход» button on the yoke.

Obviously, if they tried the throttle levers, it would have worked one way or another, and the FDR would show it – it just would not be the "automatic" goaround – complete no-brainer. So the only question is if perhaps they were sitting there clicking the «Уход» button on the yoke.

Landing modes are set with the buttons “заход” (landing) and “глиссада” (glidepath). These buttons are on the module which also contains all the light indicators of the current flight mode.

This module has "Command TurnOn GoAround " input 24, and a "GoAround Active" output 23. It is most likely that the FDR records that output 23. The logic linking these two things is quite complex, dependant on states of other buttons. I am trying to figure it out for sure, but, I thought I would give you a shot at it. (Your Russian is probably better than mine )

I uploaded the schematic for you.

PN-5.pdf - 5.2 Mb

Kulverstukas

Thank you, SadPole. As far as I can see, GOAROUND is pulse command, ie button without fixed position. Also, first thing it's perform is unconditional "Program reset" by relay 15 (along with impulse swithing of all relays in AutoLanding module), so, I think, some event must be recorded by FDR. At the other side, I can't figure how can something be recieved FROM Ш1-23 pin, it's definitely input, not output.

UPD I found (via aviasim.ru) full book from which you take this diagram. Definitely УХОД (Go Around) will not produce any signal if one don't press ГЛИССАДА (glidepass) button before and if ABSU isn't in LANDING mode.

dvv

I don't think they did it as a reaction to the RA. I don't think they did it at all - the pitch setting remained the same, and the AT kept the engines at idle. It was just a natural effect of the airplane's gradually losing the airspeed - w/o any involvement from the crew.

janeczku

This is something i am interested about too.
The report prooves that the activation of the GO-Around is recorded on the FDR on a ILS guided approach, not the push of the button! But in our case the GO-Around mode was not armed in the first place and couldnt be activated by the push of the button.
So most probably, even if the crew pushed the button, this wouldnt have been recorded on the FDR.

I am starting to consider, that they might have actually pushed the button at 1st 100m callout (the polish report states that a GA callout is heard on the CVR at that time).
The strongest argument for that is the fact, that using the automatic GA was the procedure setup by the crew minutes before.

After pressing the button, as no decreasing altitude callouts were made for next 6-7 seconds, they thought everything was going well and the GA was about to happen, so why not take advantage by looking out the window checking out the fine scenery, instead of checking boring instruments.

When the Navigator called out 100m for the second time, the FO called: "Normal".
Now that is strange call open to speculations. Maybee by that he meant:
"Yeah, we had a steep descend so there was some loss of height due to intertia after activating GA. Now we are at 100m again which means we are ascending. So everything is fine fine fine."

Then the Navigator calls out 90m, the FO is like:
"Wait a minute, i thought we were ascending".

In a matter of only 0.9 seconds the FO called "We are leaving". Which is different from the "Go Around!" he called before:
Notice the "We", aka manual GA.