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TU154 out of Sochi is missing.

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TU154 out of Sochi is missing.

Old 2nd Jan 2017, 21:10
  #261 (permalink)  
 
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Hi Kulverstukas,
Did you mean to say that the Tu-104 was an ancestor of the Tu-134? But they seem to a casual observer like me to have little in common.

Thanks for the drawing of the Tu-154 centre-overhead panel to back up the photo in post #128. Here's the link again, as we're on yet another page:
http://www.pprune.org/rumours-news/5...ml#post9621956

The gear and slat/flap selector levers, in addition to being in a position unfamiliar to crews of western jet-types, are smaller. But they are well apart and look (and feel, presumably) different from one another. Any crew mis-selection would involve either total lack of familiarity, or extreme fatigue.

One feature of the gear selector is that, like many 1950s and 1960s types, it has a neutral position (centre): probably to de-pressurise the up lines after gear retraction. (On later types, this is done automatically.)

Where are the gear-position lights/indicators?

A graphic I found on the X-PlaneReviews website by Felis Planes appears to show the slats/flaps position-indicator at the forward end of the centre pedestal, visible to both pilots:
http://xplanereviews.com/uploads/mon...bcc0e69f55.jpg
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Old 2nd Jan 2017, 21:57
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Did you mean to say that the Tu-104 was an ancestor of the Tu-134? But they seem to a casual observer like me to have little in common.
Tu-16 -> Tu-104 -> Tu-124 -> Tu-134

Where are the gear-position lights/indicators?
Top right of the middle pilot panel, next to it is flaps indication.

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Old 2nd Jan 2017, 22:10
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Old 2nd Jan 2017, 22:17
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Thanks, Kulverstukas, that is in roughly the same position as most types with which I'm familiar. But the surprise is the fact that the selector is not located where might be expected: below the indicator lights. (Great photos, BTW.)

On the possibility of fatigue-related error in selection, not detected immediately by the rest of the crew: to state the obvious, 4 a.m. is a particularly bad time of day.
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Old 2nd Jan 2017, 23:54
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but again for those who assume that the copilot simply selected flaps up instead of gear up as the reason of the crash : how does the plane continue out to the sea and even makes an u turn back before crashing in a scenario of "positive rate, gear up ( but instead of this flaps up ) " . common sense dictates that they would crash at the end of the runway. in my opinion this is not and simply cannot be the reason.
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Old 3rd Jan 2017, 05:47
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Originally Posted by aerobat77
in my opinion this is not and simply cannot be the reason...
Completely agree. However there is one more mental trap that could hav been the case:
If they were taking off with Flaps 15 due to the relatively light load, but the mental picture of the PF was Flaps 28 (the more common setting), retracting flaps one stop would have an entirely different outcome due to the huge speed gap between 15 and 0.

Last edited by andrasz; 3rd Jan 2017 at 06:17.
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Old 3rd Jan 2017, 06:29
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Originally Posted by aerobat77 View Post
how does the plane continue out to the sea and even makes an u turn back before crashing
Correct me if I'm wrong, but the location of the wreckage relative to the runway suggests that it didn't.
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Old 3rd Jan 2017, 09:45
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Even if the aircraft was airborne for the entire 70 seconds quoted, which is unlikely, it could not have completed a u-turn in such a short time.
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Old 3rd Jan 2017, 10:50
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Originally Posted by aerobat77 View Post
but again for those who assume that the copilot simply selected flaps up instead of gear up as the reason of the crash : how does the plane continue out to the sea and even makes an u turn back before crashing in a scenario of "positive rate, gear up ( but instead of this flaps up ) " . common sense dictates that they would crash at the end of the runway. in my opinion this is not and simply cannot be the reason.
Assuming a long take off roll (heavy plane per pilot), flaps up instead of gear up 3-4 seconds after lift off -- wouldn't the remaining flight time/crash location be consistent with the time it takes to retract the flaps?
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Old 3rd Jan 2017, 11:58
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well , we can only discuss currently available data but when only the published speed of 350-360 kmh is correct the flaps up theory as only reason cannot be valid.

why ? because when he was able to reach 360 kmh with a fully functioning aircraft and all engines developing rated thrust he would get away with this even when the fo selected flaps up since 360 kmh starts to be sufficient to stay airborne even in clean configuration. so this accident would never happen but it happened.

there is surely more in this than the fo grabs the wrong lever after takeoff.
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Old 3rd Jan 2017, 12:11
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Would it be a clean configuration though - in this scenario the gear would still be down.
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Old 3rd Jan 2017, 12:29
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well , in the scenario there was nothing wrong with the aircraft beyond wrong lever operated by fo i bet the tu154 has more than enough power to climb away from minimum clean speed even with the gear still down.

and again : when the current info is correct he made it to minimum clean speed !
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Old 3rd Jan 2017, 12:30
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Someone more current please correct me if I'm wrong, but according to my memory of many jump-seat rides in TU5 with 3 crew cockpit it is the PF who selects the flaps on callout from PM (speed check), with the FE adjusting throttles on verbal command (PF only handles throttles on final approach). The flap lever can only be moved one stop by compressing the two side clamps, another stop requires a release of the hold and compressing the clamps again.

I see mentally confusing original flap setting and believing to move the lever from 28 to 15 while in reality it was from 15 to 0 a plausible scenario. In either case, were it flaps instead of gear, the FDR will tell as gear/flap position parameters are recorded.
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Old 3rd Jan 2017, 14:32
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Guessing

I always dislike to make guesses, but...

Looking into this video:

https://www.youtube.com/watch?v=8qTiR7hraf0

We can see the FLAPS CONFIG IS CLEARLY 15 for the entire TO procedure, the AC does all correctly and arrives into destiny airport (Minsk) in perfect shape.
Gear is retracted about 6 secs after being airborne and 15 flaps are retracted to 0 about 115 secs later.

If this AC can TO with this configuration, why not the Sochi one?
So why many say a 28 (then retract to 15) was the "regular config"?

There is a certain data: FLAPS WERE RETRACTED when crashed after a clear photo of a wing taken when washed off from Black Sea waters.
If there was an order of flaps-up, provided they were settled 15, the only possible next position was ZERO DEGREES.

And now, what about the confusion of levers or its sequency (which I see too difficult for an experienced crew)?

There is the slight possibility of a confusion (flaps-up instead of gear-up first), but the TU-154 is a very powerful bird. If it reached +/- 300 km/h at about 250 m (800 feet), even with the gear DOWN and FLAPS 0 would push-up with no problem until things were cleared and the cockpit people calmed enough to settle things to "regular".
As far as I know, throttles on a TU-154 are FE (flight engeneer) commanded. They're not a responsibility of the two in command, so it's very difficult to think in a loss of thrust due to a "cockpit mess".

And also confusing is the RIGHT TURN. If the AC is doing nonsense (whatever the reason) why the hell any PiC would like to make a turn in such a conflictive scenario? This puzzles me...
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Old 3rd Jan 2017, 15:25
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Originally Posted by guadaMB View Post
I always dislike to make guesses, but...

Looking into this video:

https://www.youtube.com/watch?v=8qTiR7hraf0

We can see the FLAPS CONFIG IS CLEARLY 15 for the entire TO procedure, the AC does all correctly and arrives into destiny airport (Minsk) in perfect shape.
Gear is retracted about 6 secs after being airborne and 15 flaps are retracted to 0 about 115 secs later.
Whatever the reason for the flap retraction was -- wouldn't it be much too early in the flight for them to be retracted? It seems more typical like in your video that it happens after 120 seconds of flight.
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Old 3rd Jan 2017, 15:26
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And also confusing is the RIGHT TURN. If the AC is doing nonsense (whatever the reason) why the hell any PiC would like to make a turn in such a conflictive scenario?
There is no evidence of right turn except poorly drawn draft of a/c route, presented at the first press-conference, when rescue operation just started.
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Old 3rd Jan 2017, 15:48
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There is no evidence of right turn except poorly drawn draft of a/c route, presented at the first press-conference, when rescue operation just started.
More to the point, planned route, based on the SID (I presume).
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Old 3rd Jan 2017, 16:28
  #278 (permalink)  
 
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Originally Posted by aerobat77 View Post
well , we can only discuss currently available data but when only the published speed of 350-360 kmh is correct the flaps up theory as only reason cannot be valid.

why ? because when he was able to reach 360 kmh with a fully functioning aircraft and all engines developing rated thrust he would get away with this even when the fo selected flaps up since 360 kmh starts to be sufficient to stay airborne even in clean configuration. so this accident would never happen but it happened.

there is surely more in this than the fo grabs the wrong lever after takeoff.
If flaps were retracted too soon and a/c lost lift it may be that they reached 350kmh nose down but it was not enough to arrest descent before hitting sea surface. Out of height, out of options. But the poor souls were maybe closer to salvation than we may think.
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Old 3rd Jan 2017, 17:11
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Originally Posted by Kulverstukas View Post
There is no evidence of right turn except poorly drawn draft of a/c route, presented at the first press-conference, when rescue operation just started.
Oooppsss...
I thought it was something confirmed.
Sorry to include it in my guesses...


If flaps were retracted too soon and a/c lost lift it may be that they reached 350kmh nose down but it was not enough to arrest descent before hitting sea surface. Out of height, out of options. But the poor souls were maybe closer to salvation than we may think.

This could happen if things went "the simpler of mistakes the bigger the problem".
The AC took off with flaps 15, once airborne PiC commanded "gear up" and the FO made THE mistake: flaps up.
Normally the retraction of gears is in the region of 5 to 8 seconds after being airborne.
As far as I could chronometre, flaps from 15 to 0 take 18 secs.
It's VERY possible all in the 70 seconds (is this timing confirmed, Mr. Kulverstukas?) because once the flaps retraction begins, also begins the lack of lift, in geometrical progression, hitting waters at 300+ km/h and destroying the AC.
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Old 3rd Jan 2017, 17:19
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is this timing confirmed
70 second and "10 second of catastrophic event unfolding" are from official press conference after CVR/FDR readout, but not clear what this 70 sec are counted from.
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