Polish President and wife killed in Tu-154 crash

[Gabriel]

If it is true that the first channel of AP was turned off at the point when sufficient force was applied to the control column, then assuming a descent rate close to 8 m/s the plane should have lost min 30m of altitude (according to the official report) or 50m according to Tu-154 Manual.
The plane lost exactly 7.6m of altitude, then started climbing.

If we assume that the laws of physics are still correct, then the AP must have been turned off somewhere between 30 and 50m above the lowest point. That would shift that moment 5 - 6 seconds back when the plane was about 70m above ground.

I didn't read the report nor the manual, but that makes no sense.

It takes just a 1.4Gs pull during 1.9 seconds to bring something from a descent of 8 m/2 to 0 m/s in 7.6m. It takes just 1.2 Vs to produce enough lift (at stall AoA) for 1.4Gs, Vref is 1.3 Vs (enough for a 1.7Gs pull) and the plane was flying faster than Vref. So that's pretty attainable, especially when the pilot made such a big pull for the investigators to say that the plane would have stalled if it hadn't crashed first.

Also, loosing 30m (50m) would be nearly a full 4 (5) seconds descent at a constant rate of 8m/s. Unthinkable.

[Northwester]

I didn't read the report nor the manual, but that makes no sense.

It takes just a 1.4Gs pull during 1.9 seconds to bring something from a descent of 8 m/2 to 0 m/s in 7.6m. It takes just 1.2 Vs to produce enough lift (at stall AoA) for 1.4Gs, Vref is 1.3 Vs (enough for a 1.7Gs pull) and the plane was flying faster than Vref. So that's pretty attainable, especially when the pilot made such a big pull for the investigators to say that the plane would have stalled if it hadn't crashed first.

Also, loosing 30m (50m) would be nearly a full 4 (5) seconds descent at a constant rate of 8m/s. Unthinkable.

This is from the report.

[Gabriel]

This is from the report.

Hmmm...

Do you happen to have an English version?

Anyway, some numbers are quite straightforward.

At 1.4Gs (one of the accelerations used in the report) you use 1G to sustain flight and another 0.4Gs to change the direction of the flight (i.e. pull up).

Since 0.4Gs is roughly 4 m/s/s, it takes roughly 2 seconds to go from 8 m/s to 0 m/s. And even if you used all those 2 seconds going down at 8 m/s (which you don't because you start with 8 but end with 0), then you would descend 16m.

To make a better number, the formula of change of speed "V" (starting or finishing at 0 m/s) in a given distance "h" at a given constant acceleration "a" is

V=sqrt(2*a*h)

So it follows that h = V^2 /2a
h = (8 m/s)^2 / (2*4 m/s/s)
h = (8 m/s)^2 / 8 m/s/s
h = 8m

As I've said many times before, you can't beat Newton.

So, if the number the Russians found at 1.4Gs is 20m, then one of the following must be true:

The initial vertical speed was not 8 m/s, or
The aceleration was not constant 1.4Gs, or
Newton was wrong, or
I know crap about Physics, or
A combination of the above.

By the way, 20m is not 30m.

[Northwester]

Hmmm...

Do you happen to have an English version?

English version of what? The page I attached was in English.

[Northwester]

Hmmm...

Do you happen to have an English version?

Anyway, some numbers are quite straightforward.

At 1.4Gs (one of the accelerations used in the report) you use 1G to sustain flight and another 0.4Gs to change the direction of the flight (i.e. pull up).

Since 0.4Gs is roughly 4 m/s/s, it takes roughly 2 seconds to go from 8 m/s to 0 m/s. And even if you used all those 2 seconds going down at 8 m/s (which you don't because you start with 8 but end with 0), then you would descend 16m.

To make a better number, the formula of change of speed "V" (starting or finishing at 0 m/s) in a given distance "h" at a given constant acceleration "a" is

V=sqrt(2*a*h)

So it follows that h = V^2 /2a
h = (8 m/s)^2 / (2*4 m/s/s)
h = (8 m/s)^2 / 8 m/s/s
h = 8m

As I've said many times before, you can't beat Newton.

So, if the number the Russians found at 1.4Gs is 20m, then one of the following must be true:

The initial vertical speed was not 8 m/s, or
The aceleration was not constant 1.4Gs, or
Newton was wrong, or
I know crap about Physics, or
A combination of the above.

By the way, 20m is not 30m.

The Russians used 1.2, 1.3 and 1.4Gs resulting in 28, 22 and 20m. But that's beside the point.

If you look at the trajectory, you'll notice that the plane was descending not as fast right before they, according to the Russians, turned off the AP. The actual descent rate then was about 5.6 m/s. That would have caused, according to your calculations, only about 3.92m loss of altitude before starting a climb.

Obviously some other factors played a role there, or laws of physics need to be rewritten.

[Gabriel]

English version of what? The page I attached was in English.

It was a joke. It's English words combined in some semi-understandable fashion.

[Northwester]

It was a joke. It's English words combined in some semi-understandable fashion.

I got it. Just wanted to make sure some strange filter was not converting it to Chinese to add to the confusion

[Northwester]

So if we assume that the Russian GA simulation is correct and the flight data in the report is correct, the plane ends up at point B, 20m below the AP off point, way underground.

That's not possible. So either the GA simulation is incorrect or the flight data is flawed (AP off point earlier, descent rate different, etc).

Side point: don't know if this is significant, but TAWS froze before the plane hit the ground.

[Northwester]

There are some opinions that parts of CVR recording are missing. The crew of Tu-154 approached the aerodrome from the East (259) instead of from the West (79). They could not have decided on their own about the direction. But there is nothing in the CVR transcript about ATC instructing them to approach from the East.

The crew of IL-76 received a clear message:
08:54:17 ATC - 8-17th, on Korsazh 3rd level, haze, visibility 4, wind 140 degrees, 2 meters. Temperature +2, pressure 7-45, 7-45. For landing 2-5-9. Crossing level 1500, OSP with RSP.

OSP stands for Landing System Instruments (NDB1 and NDB2)
RSP stands for Landing Radar System

Info like that must have been given to Tu-154, but it is not in the transcript.

[justLOT787]

So we are ready to commemorate the first year anniversary of the horrific accident that killed the Polish president his wife and 94 other people. And yet nothing has been done by the Polish government or EU to investigate the accident. The black boxes are still in Russia and the planes wreck is also in Russia! So what is going on hear? If it was any other “accident” involving for example US, German, French, presidents in on Russian soil I really don’t think Russians would be doing the investigation by them self’s and would have not be holding the black boxes and the planes wrack and telling everyone their versions and what suits them. If it was just a regular accident then Russian Communist government would have returned the black boxes and planes wrack back to Poland, right owner! But it wasn’t a regular accident!! As a Polish-American I demand that Russia return the property to Poland, that property is the black boxes and the planes wrack. I also call on US to step is and do their own investigation to aid Poland even is current Polish government doesn’t care!!! The truth always comes out at the end!!

[Curtis Malone]

So we are ready to commemorate the first year anniversary of the horrific accident that killed the Polish president his wife and 94 other people. And yet nothing has been done by the Polish government or EU to investigate the accident. The black boxes are still in Russia and the planes wreck is also in Russia! So what is going on hear? If it was any other “accident” involving for example US, German, French, presidents in on Russian soil I really don’t think Russians would be doing the investigation by them self’s and would have not be holding the black boxes and the planes wrack and telling everyone their versions and what suits them. If it was just a regular accident then Russian Communist government would have returned the black boxes and planes wrack back to Poland, right owner! But it wasn’t a regular accident!! As a Polish-American I demand that Russia return the property to Poland, that property is the black boxes and the planes wrack. I also call on US to step is and do their own investigation to aid Poland even is current Polish government doesn’t care!!! The truth always comes out at the end!!

As a Polish-American, you're obviously just very slightly (maybe just over a smidge or so) biased. The truth did come out and, as a Polish-American, you don't like it.

[justLOT787]

What truth came out? I don’t see any truth all I see and hear is just lies, cover up after cover up. If you want to see and hear the truth then Polish investigators need to get the black boxes and the planes wreckage to Poland and do the right investigation. The truth that you believe in is the lie that Russian investigators from MAK have told you. And if this is called truth then why are the Russians not giving up the plane and its boxes to Poland so they could do the proper investigation? Please give me a smart and educated answer because I don’t buy lies and cover-ups and made up fake reports. Russia should return Poland’s property back to POLAND ASAP!!!!

[Curtis Malone]

What truth came out? I don’t see any truth all I see and hear is just lies, cover up after cover up. If you want to see and hear the truth then Polish investigators need to get the black boxes and the planes wreckage to Poland and do the right investigation. The truth that you believe in is the lie that Russian investigators from MAK have told you. And if this is called truth then why are the Russians not giving up the plane and its boxes to Poland so they could do the proper investigation? Please give me a smart and educated answer because I don’t buy lies and cover-ups and made up fake reports. Russia should return Poland’s property back to POLAND ASAP!!!!

I think all your questions have been already answered over this nearly fifty-page thread, but what the heck, I have a day off, so let's recap a couple of things.

Firstly, this was a military aircraft that crashed at a military airfield, so whatever notions you have for the way civilian crashes are handled (whether those notions are true or not) are not applicable here. In fact, I would challenge you to find a single example of a military aircraft from one country crashing at a military airfield in another and said another country letting said first country conduct the investigation.

Secondly, I hardly think the Polish side in this case would be the more unbiased one. The very fact the approach was even attempted (even if it had been successful) under those weather conditions (and those conditions are not in dispute) paints the Polish Air Force in a very poor light, and you want this same Polish Air Force to conduct the investigation and are even suggesting that you would believe their findings over those of the Russian side (who has nothing to gain but covering anything up)?

I have a feeling that had this been, as you put it, "any other crash", you would have no issues whatsoever with the Russian side.

[justLOT787]

Look what I'm writing about is that military or civilian crash either way you look at it, the plane is property of Poland, the black boxes are property of Poland and every thing should be returned to it righteous owner Poland. If Russian government doesn’t have any thing to hide then they should have returned the planes wreckage back to Poland after they did their investigation so Poland could do theirs. And after all that investigation you get both countries together and compare notes and make the right report. But the thing is that I think Russians did some thing wrong and are trying to cover some thing up if NOT then return black boxes back to Poland. Russian authorities have both the wreck and black boxes and they know what really happened and will cover up as much as they possibly can!

[Peter Kesternich]

NO NO NO... not again... PLEEEEEASE...

justLOT78 - when do you Polish people (and those of Polish origin) finally realize that the world is not out to get you???

The accident was Poland's or rather the Polish pilot's fault. Period. Okay - possibly also the Polish president's who pressured the pilot into busting minimums.

What do you think would be worth the trouble for the Russians to cover up? Do you really think there is a conspiracy here to kill the Polish president? Sorry - but he wasn't that important. And if the Russians simply made a mistake, they have no reason to cover it up. They won't really care that much.