Russian B737 Crash at Kazan.
DOVE
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Very interesting reading:
From
Adsto
15th Apr 2005: B737 Stall
http://www.pprune.org/1842832-post1.html
From
CaptainSandL #5 (permalink)
737-300 at 40T, stick shaker triggers at approx 1.09Vs with flap 5 & gear up and approx 1.07Vs with flap 30 & gear down.
From
BOAC #6 (permalink)
Thanks for the Vs figures. 1.07 is not much when you look at a Vs of around ?110kts? If my fading memory serves me right (going back to 1988) we went to the first proper 'symptom' of the stall (excluding stick shake), but Tempus Fugit may be playing tricks! IIRC We always found that at 1kt/sec you did not have enough back stick to keep the nose high enough to reach anything other than a gentle 'mush out', and never got to stall speed. I assumed the point of it was to try to ensure there were no 'nasty' asymmetries waiting to bite - but we never found out
But also:
http://www.pprune.org/tech-log/431167-737-ng-sts.html
airyana 19th Oct 2010, 22:17
"As airspeed decreases towards stall speed, the speed trim system trims the stabilizer nose down and enables trim above stickshaker AOA. With this trim schedule the pilot must pull more aft column to stall the airplane."
Can anyone clarify what is meant by: "enables trim above stickshaker AOA"
And why ??
BOAC 22nd Oct 2010, 16:08
Never really understood it and ignored it - it is confusing because stab nose down is a/c nose up. I suspect they
missed out the word 'airplane'. I expect Cpt SandL or Checkboard will know the answer
Whippersnapper 24th Oct 2010, 18:02
It has been a while, but as I remember it, as the stall is approached, the elevator feel shift centre position moves and its hydraulic pressure increases. This is combined with the speed trim system trimming (aircraft) nose down. The combination is meant to emulate the old fashioned "stick pusher" on older aircraft with hydraulic controls.
My guess is that the speed trim is inhibited as the stick shaker is activated (perhaps as an assumption a trim system malfunction is the reason for the high AOA), but if AOA is further increased to the point that the stall is imminent, the speed trim is reactivated to trim nose down.
I was spared the suction of a good portion of dust.
From
Adsto
15th Apr 2005: B737 Stall
http://www.pprune.org/1842832-post1.html
From
CaptainSandL #5 (permalink)
737-300 at 40T, stick shaker triggers at approx 1.09Vs with flap 5 & gear up and approx 1.07Vs with flap 30 & gear down.
From
BOAC #6 (permalink)
Thanks for the Vs figures. 1.07 is not much when you look at a Vs of around ?110kts? If my fading memory serves me right (going back to 1988) we went to the first proper 'symptom' of the stall (excluding stick shake), but Tempus Fugit may be playing tricks! IIRC We always found that at 1kt/sec you did not have enough back stick to keep the nose high enough to reach anything other than a gentle 'mush out', and never got to stall speed. I assumed the point of it was to try to ensure there were no 'nasty' asymmetries waiting to bite - but we never found out
But also:
http://www.pprune.org/tech-log/431167-737-ng-sts.html
airyana 19th Oct 2010, 22:17
"As airspeed decreases towards stall speed, the speed trim system trims the stabilizer nose down and enables trim above stickshaker AOA. With this trim schedule the pilot must pull more aft column to stall the airplane."
Can anyone clarify what is meant by: "enables trim above stickshaker AOA"
And why ??
BOAC 22nd Oct 2010, 16:08
Never really understood it and ignored it - it is confusing because stab nose down is a/c nose up. I suspect they
missed out the word 'airplane'. I expect Cpt SandL or Checkboard will know the answer
Whippersnapper 24th Oct 2010, 18:02
It has been a while, but as I remember it, as the stall is approached, the elevator feel shift centre position moves and its hydraulic pressure increases. This is combined with the speed trim system trimming (aircraft) nose down. The combination is meant to emulate the old fashioned "stick pusher" on older aircraft with hydraulic controls.
My guess is that the speed trim is inhibited as the stick shaker is activated (perhaps as an assumption a trim system malfunction is the reason for the high AOA), but if AOA is further increased to the point that the stall is imminent, the speed trim is reactivated to trim nose down.
I was spared the suction of a good portion of dust.
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The pitch up thrust couple is probably the start of the problem for the crew, not sure which engine thrust the airline have on the 500 (some Russian outfit operate 500's with 22.5k which give F 16 like climb rates)
For most western operators its max two approaches and divert unless there is a significant improvement in weather conditions, this lot appeared not follow even basic procedures with regard to MDH/MSA
1 It won't be a terrorist event.
2 It won't be an aircraft failure
3 It will be crew induced loss of SA resulting in undesirable aircraft state.
Just read how lucky the crew (Thomson's Bournemouth & Jet2 at Chambrey ) were with very high pitch up and slow speed following a go around or for different reasons the Norwegian crew at Kittila with frozen/jammed Stab, with lots of thrust the aircraft will go well below 100 knt's with out stall even at near 40 degrees nose up, at least for a short while
For most western operators its max two approaches and divert unless there is a significant improvement in weather conditions, this lot appeared not follow even basic procedures with regard to MDH/MSA
1 It won't be a terrorist event.
2 It won't be an aircraft failure
3 It will be crew induced loss of SA resulting in undesirable aircraft state.
Just read how lucky the crew (Thomson's Bournemouth & Jet2 at Chambrey ) were with very high pitch up and slow speed following a go around or for different reasons the Norwegian crew at Kittila with frozen/jammed Stab, with lots of thrust the aircraft will go well below 100 knt's with out stall even at near 40 degrees nose up, at least for a short while
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LNIDA
Russian report : CFM 56 3 C1
(rated at 23.500 klbs)
The pitch up thrust couple is probably the start of the problem for the crew, not sure which engine thrust the airline have on the 500 (some Russian outfit operate 500's with 22.5k which give F 16 like climb rates)
(rated at 23.500 klbs)
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For most western operators its max two approaches and divert...
I suppose that it is caused by Russian terminology. G/A is in Russian "second circuit" the final turn is "the fourth turn". So our disaster after second circuit can be misunderstood like third attempt to land.
Landing weight was 42 t, ie gravity force approx 410 kN. Max. thrust of both engines 200 kN. Good ratio weight/thrust=2
Last edited by Karel_x; 2nd Dec 2013 at 17:37.
map shifts
DOVE
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A SPIN
… when a GA was initiated, either due to the strong pitch up moment caused by the engines and the vertical upward component of traction or 'apparent lift', it was not easy, or even impossible, to stop the rapid attitude increase if not by trimming down or reducing engine thrust. …
So with:
-High-pitch attitude
-Slow/decreasing-speed, with AOA approaching stall
Whippersnapper http://www.pprune.org/tech-log/43116...ml#post6014975
…the elevator feel shift centre position moves and its hydraulic pressure increases. This is combined with the speed trim system trimming (aircraft) nose down. The combination is meant to emulate the old fashioned "stick pusher" on older aircraft with hydraulic controls.
My guess is that the speed trim is inhibited as the stick shaker is activated (perhaps as an assumption a trim system malfunction is the reason for the high AOA), but if AOA is further increased to the point that the stall is imminent, the speed trim is reactivated to trim nose down.
BOAC :http://www.pprune.org/tech-log/43116...ml#post6011471
…We always found that at 1kt/sec you did not have enough back stick to keep the nose high enough to reach anything other than a gentle 'mush out', and never got to stall speed. I assumed the point of it was to try to ensure there were no 'nasty' asymmetries waiting to bite…
It's just a little rotation (some rudder, some aileron, different thrust on the engines) on the yaw-axis to cause a spin.
OR
When the speed became so low, with AOA approaching stall the STS activated commanding automatically the pitch trim towards AND, the elevator feel pushing, and at least one CM distracted to communicate with TWR for 16 sec…
With so little altitude to even try a recovery..
The fate was written
… when a GA was initiated, either due to the strong pitch up moment caused by the engines and the vertical upward component of traction or 'apparent lift', it was not easy, or even impossible, to stop the rapid attitude increase if not by trimming down or reducing engine thrust. …
So with:
-High-pitch attitude
-Slow/decreasing-speed, with AOA approaching stall
Whippersnapper http://www.pprune.org/tech-log/43116...ml#post6014975
…the elevator feel shift centre position moves and its hydraulic pressure increases. This is combined with the speed trim system trimming (aircraft) nose down. The combination is meant to emulate the old fashioned "stick pusher" on older aircraft with hydraulic controls.
My guess is that the speed trim is inhibited as the stick shaker is activated (perhaps as an assumption a trim system malfunction is the reason for the high AOA), but if AOA is further increased to the point that the stall is imminent, the speed trim is reactivated to trim nose down.
BOAC :http://www.pprune.org/tech-log/43116...ml#post6011471
…We always found that at 1kt/sec you did not have enough back stick to keep the nose high enough to reach anything other than a gentle 'mush out', and never got to stall speed. I assumed the point of it was to try to ensure there were no 'nasty' asymmetries waiting to bite…
It's just a little rotation (some rudder, some aileron, different thrust on the engines) on the yaw-axis to cause a spin.
OR
When the speed became so low, with AOA approaching stall the STS activated commanding automatically the pitch trim towards AND, the elevator feel pushing, and at least one CM distracted to communicate with TWR for 16 sec…
With so little altitude to even try a recovery..
The fate was written
Last edited by DOVES; 3rd Dec 2013 at 16:52.
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"> > map shifts
> Unlikely I'd hazard to guess, never known this to be a problem or contributory to a single fatal accident , although heard all the scare stories, but would be interested to know if they did a full alignment and the state of the IRU's."
If you've got DME along the route isn't that sufficient to stop map shift? The IRUs can be way off but DME or GPS updating overrides them doesn't it?
> Unlikely I'd hazard to guess, never known this to be a problem or contributory to a single fatal accident , although heard all the scare stories, but would be interested to know if they did a full alignment and the state of the IRU's."
If you've got DME along the route isn't that sufficient to stop map shift? The IRUs can be way off but DME or GPS updating overrides them doesn't it?
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Clandestino
It's a collation of several posts on on the topic.
Just my two cents.
Much could be inferred from the answer to my question:
http://www.pprune.org/8183803-post344.html
...anyone knows how to assess the direction to which the camera, which frames the plane swooping to the ground almost vertically, is oriented?...
In any case is it possible to access the FDR?
It's a collation of several posts on on the topic.
Just my two cents.
Much could be inferred from the answer to my question:
http://www.pprune.org/8183803-post344.html
...anyone knows how to assess the direction to which the camera, which frames the plane swooping to the ground almost vertically, is oriented?...
In any case is it possible to access the FDR?
In any case is it possible to access the FDR?
Still nothing...
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All these theories about auto pitch trim behaviour. I just think that they fixated on the ASI and pushed and trimmed until the speed started to build up. At that point, the pitch attitude was probably too low and the pitch trim too far forward for recovery at that altitude.
Remember how they got into this situation in the first place: On the go-around, they let the nose go up to 25 degrees until the speed decayed down to 125kts. I think that means that they would not have paid any attention to the ADI. Neither then, nor at the summit when the aircraft went into negative pitch.
Almost all the captain's 2500 hour flying experience was on the 737, and less than 500 hours in command on it. With the ease autoflight makes flying these days, and company policies that discourage hand flying, they couldn't have had that much experience at hands on raw data instrument flying.
Worldwide, the number of accidents due to loss of control because of poor instrument flying skills is becoming a concern. Automation makes things easy, but losing it makes it far worse than never having had the luxury of having it in the first place. I can't imagine a raw data instrument scan to be up to speed when the only hands on flying done is the take off up to 200-400 feet, and landing below 1000 feet whilst following the flight director.
Remember how they got into this situation in the first place: On the go-around, they let the nose go up to 25 degrees until the speed decayed down to 125kts. I think that means that they would not have paid any attention to the ADI. Neither then, nor at the summit when the aircraft went into negative pitch.
Almost all the captain's 2500 hour flying experience was on the 737, and less than 500 hours in command on it. With the ease autoflight makes flying these days, and company policies that discourage hand flying, they couldn't have had that much experience at hands on raw data instrument flying.
Worldwide, the number of accidents due to loss of control because of poor instrument flying skills is becoming a concern. Automation makes things easy, but losing it makes it far worse than never having had the luxury of having it in the first place. I can't imagine a raw data instrument scan to be up to speed when the only hands on flying done is the take off up to 200-400 feet, and landing below 1000 feet whilst following the flight director.
Yancey
Believe it or not, but not all DME xmitters are fixed.
In the early days of my company operating the 747-400 we noticed regular, large map shifts when flying in the Taiwan area. It transpired that the FMCS was locking on to a military installation, which was located on the back of a lorry and therefore moved! Maybe similar in Russia?
Believe it or not, but not all DME xmitters are fixed.
In the early days of my company operating the 747-400 we noticed regular, large map shifts when flying in the Taiwan area. It transpired that the FMCS was locking on to a military installation, which was located on the back of a lorry and therefore moved! Maybe similar in Russia?
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...we noticed regular, large map shifts when flying in the Taiwan area. It transpired that the FMCS was locking on to a military installation, which was located on the back of a lorry and therefore moved! Maybe similar in Russia?
...In Taiwan!
I can't imagine a raw data instrument scan to be up to speed when the only hands on flying done is the take off up to 200-400 feet, and landing below 1000 feet whilst following the flight director.
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But we're not talking so much about precision instrument Flying in this case.
It seems to me that in the end it was just a matter of pushing or pulling (obviously correctly interpreting the macroscopic indications of the ADI), first to counter act the initial strong climb effect, and then to stop and reverse as necessary the hard pitch down rate.
Or am I wrong?
It seems to me that in the end it was just a matter of pushing or pulling (obviously correctly interpreting the macroscopic indications of the ADI), first to counter act the initial strong climb effect, and then to stop and reverse as necessary the hard pitch down rate.
Or am I wrong?
Your use of the term "precision" is a red herring, DOVES.
Fundamental instrument flying is what he was referring to.
Fundamental instrument flying is what he was referring to.
I can't imagine a raw data instrument scan to be up to speed when the only hands on flying done is the take off up to 200-400 feet, and landing below 1000 feet whilst following the flight director.
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I wonder if the final accident report will concentrate solely on the execution of the G/A, the subsequent mis-handling and the following on further mis-handling into the fatal dive.
If so they will be missing quite a bit. The accident started i.e. the first hole lined up, when they lost SA a long way out on the approach. Follow the sequence of the flight and its lateral & vertical navigation to the eventual G/A point and the holes were all lining up. The correct decision was a G/A; good call. It is sad and shameful that pushing TOGA was the lining up of the penultimate hole. They still had a chance, but by not controlling the attitude all the holes lined up.
There will need to much scrutiny of their training and overall training dept. Will that happen. It did when an American Airline waggled the tail off an Airbus. The root causes were found in the training culture. Perhaps there will be a root cause weakness found here too, starting with SA awareness and then a G/A. But ending up at 1000' way off the LOC is scary.
Much to wait and see about.
If so they will be missing quite a bit. The accident started i.e. the first hole lined up, when they lost SA a long way out on the approach. Follow the sequence of the flight and its lateral & vertical navigation to the eventual G/A point and the holes were all lining up. The correct decision was a G/A; good call. It is sad and shameful that pushing TOGA was the lining up of the penultimate hole. They still had a chance, but by not controlling the attitude all the holes lined up.
There will need to much scrutiny of their training and overall training dept. Will that happen. It did when an American Airline waggled the tail off an Airbus. The root causes were found in the training culture. Perhaps there will be a root cause weakness found here too, starting with SA awareness and then a G/A. But ending up at 1000' way off the LOC is scary.
Much to wait and see about.