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B-738 Crash in Russia Rostov-on-Don

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B-738 Crash in Russia Rostov-on-Don

Old 8th Apr 2016, 15:43
  #1141 (permalink)  
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When flying the MAP manually with a relativly light B737, one easily might apply to much ND Trim in attempting to capture a low level-off altitude. Since the speed might increase rapidly one can find himself in a condition with Stab Trim at 0 / Full ND and T/L retarding to more or less idle.
Yep, possibly confusion over whether the published missed approach altitude of 600 meters QFE still applies after an apparent verbal clearance to FL 80 on the missed approach. The 600 meters constraint is probably still in the in the FMC from earlier discussions on this thread with maybe 8000 in the altitude window. They zoom upward on the miss toward FL 80 but the flight directors and possibly autothrottles still see the lower altitude and give cues to descend. At 900 meters the PF thinks he is 1000 feet above the proper altitude and does the -1 g pushover.

Here's a similar scenario with a Korean Mad Dog freighter out of SHA in 1999:

After takeoff the first officer contacted Shanghai Departure and received clearance to climb to 1500 metres (4900 feet): "Korean Air six three one six now turn left direct to November Hotel Whiskey climb and maintain one thousand five hundred meters."

When the aircraft climbed to 4500 feet in the corridor, the captain, after receiving two wrong affirmative answers from the first officer that the required altitude should be 1500 feet, thought that the aircraft was 3000 feet too high. The captain then pushed the control column abruptly and roughly forward causing the MD-11 to enter a rapid descent.

Both crew members tried to recover from the dive, but were unable. The airplane crashed into an industrial development zone 10 kilometers (6 miles) southwest of Hongqiao airport. The plane plunged to the ground, plowing into housing for migrant workers and exploded.
ASN Aircraft accident McDonnell Douglas MD-11F HL7373 Shanghai-Hongqiao Airport (SHA)
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Old 8th Apr 2016, 16:29
  #1142 (permalink)  
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PJ2 I found something about the Go Arounds:
It is study on Airplane state awareness during a go around.
It lists many accidents, including the ones you mention.

http://caa.gov.il/index.php?option=c...id=669&lang=he
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Old 8th Apr 2016, 16:57
  #1143 (permalink)  
 
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It's not rocket science! Fly a GA like a normal take off, TO/GA, accelerate, rotate 2/3' per second and look for 15' pitch. Positive rate..... problem is that you actually have to fly the airplane.
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Old 8th Apr 2016, 17:52
  #1144 (permalink)  
 
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From today's MAK update

In the process of the second approach, carried out in manual mode, the crew at an altitude of 220 m (4 km from the runway) decided to "go-around" and initiated a climb with the engines in takeoff mode. At an altitude of 900 meters the crew pushed the yoke forward and the stabilizer was put 5 degrees into dive, causing the plane to go into a vigorous descent with the vertical acceleration up to to -1 g. Subsequent actions by the crew did not prevent a collision with the ground. The collision occurred at speeds exceeding 600 km / h with a pitch angle to dive more than 50 deg.
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Old 8th Apr 2016, 18:05
  #1145 (permalink)  
 
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If a windshear GA,then they would not change config.Once they get that positive shear back,their IAS will increase by a huge amount,and now they have flap overspeed(flaps still at 30),so FD commands increasing ANU.Pilot follows FD religiously at first.Red overspeed bar reinforces this need.This could be 30-40 deg ANU.This sets the trap.
Was he flying HUD or PFD/FD?We've already had it confirmed from HUD pilots that they revert to PFD often.We need more input from HUD pilots.
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Old 8th Apr 2016, 18:20
  #1146 (permalink)  
 
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Except that the FR24 flight profile seems to suggest a normal and consistent go around under control with the expected acceleration phase and normal missed approach and acceleration speeds until the sudden and extreme nose over.
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Old 8th Apr 2016, 19:11
  #1147 (permalink)  
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PBY, yes thanks, have seen the study, and had passed it on to some carriers.

Flight data analysis shows that the go-around manoeuvre is generally performed safely enough but not always precisely.

This is in terms of:

- pitch attitude achieved vice required,
- timely configuration changes, (flaps retracted to g/a setting, gear up) and,
- precise altitude capturing and route tracking.

Overall, power set for the g/a, and speed control do not seem to be a problem.

Often, (from sim experiences), handling & performance of the g/a manoeuvre can get side-lined and stopped mid-stream if the PM/PNF does not make the "positive climb/rate" call in a timely manner, (or omits it entirely). Inevitably this leaves the gear down until someone wonders about the noise and power settings...

In terms of cockpit management, prioritizing actions sometimes gets lost amidst the important but definitely-secondary nav and communications requirements. Flying the airplane is the first (and only) short-term requirement, (first ten seconds, say), and when things are well in hand ensuring navigation is being done.

Some will disagree with this view because you can't just fly straight ahead to 3000ft and airspace must be respected. Ideally these are done almost simultaneously but the first priority is still full control of the airplane.

I say this because go-arounds that result in an accident result almost exclusively from a loss of S.A/loss of control, (vise CFIT, mid-air collision, mechanical/technical failure, encounters with serious weather phenomenon, etc.)

I realize that some g/a required routings, altitudes and perhaps speeds are complex due to the proximity of terrain or other airports and their airspace requirements. But full control of the aircraft is primary.
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Old 8th Apr 2016, 19:13
  #1148 (permalink)  

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"SUDDEN AND EXTREME NOSE OVER"
Are the keywords!
Very strange!
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Old 8th Apr 2016, 19:49
  #1149 (permalink)  
 
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Originally Posted by thf View Post
"At a height of 900 m there was a simultaneous control column nose down input and stabilizer 5-degree nose down deflection.."
The control column nose down is a PF commanded input. It is the STS that is of particular interest in this scenario where the aircraft was on manual, ie a/p disengaged. STS most frequently operates on t/o, climb and go around.
The puzzling of the STS against the background of the investigators announcement that no systems faults have been found, is the word "simultaneous". Namely that both commanded input and stab deflection occurred at the same time. Cannot quite see how both could have been achieved simultaneously.
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Old 8th Apr 2016, 22:15
  #1150 (permalink)  
 
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At an altitude of 900 meters the crew pushed the yoke forward and the stabilizer was put 5 degrees into dive, causing the plane to go into a vigorous descent with the vertical acceleration up to to -1 g.
The answer may lie in that statement. They pulled negative, and I have seen many strange reactions to negative, especially as many new generation pilots may never have done aeros. On one occasion turbulence on approach caused a momentary 0g, and the f/o let go of the controls, screamed, and grabbed the ceiling. Bit of a worry. On another occasion in training a short 0g was confused with a stall, resulting is a substantial push forwards to 'unstall' the aircraft, resulting in -1 or more.

In this case the input of 5 units of trim is not normal. That is a lot of trim, even if the flaps are down (works at 3x speed). There is no reason to use trim like that if pitching forwards, as the cc is rarely that heavy that you need to unload simultaneously while pitching. Someone should see how long it takes to run five degrees, with the flaps down (no longer on 737). There are elements here pointing towards a sudden pitch to catch an altitude, that developed into a new unusual experience -- a 0g float -- that provoked a wrong reaction.

Last edited by silvertate; 9th Apr 2016 at 08:50.
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Old 9th Apr 2016, 02:38
  #1151 (permalink)  
 
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Namely that both commanded input and stab deflection occurred at the same time. Cannot quite see how both could have been achieved simultaneously.
If there is a lot of forward force required on the control column it is a "natural" reaction to use the trim to help.
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Old 9th Apr 2016, 07:28
  #1152 (permalink)  
 
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What is 5 degrees of trim? Trim is expressed in units not degrees.
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Old 9th Apr 2016, 11:00
  #1153 (permalink)  
 
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according to 737flightsim.com total stab travel is - 0.2 to +16.9 trim units and 1 degree of stab travel = 1 trim unit. Full scale travel thus = 17.1 units or degrees. Stab is neutral at 4 trim units.
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Old 9th Apr 2016, 11:54
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Looking at this more from a human factors than technical: people speculate on disorientation, mis-reading a HUD, and other factors in the execution of the GA. I have no answers to my questions, I admit. They had performed the same manoeuvre 2hrs earlier and from a similar very safe height; thus no rush, no panic, no surprises. So why does it go horribly wrong? It is said they achieved -1g. Anyone will feel that, it is not a gentle force. You will feel something is not correct; you should understand what is causing it and the PFD will confirm it and tell you what needs to be done about it.
Summary:
- this was a repeat of a previous successful manoeuvre.
- it was at a safe height, no rush, no surprise, no panic.
- -1g is an unmissable force
- PFD showing attitude in the brown is unequivocal.

Curious.

I'm curious & disturbed to hear some guys use trim to help level off. Agh! I'm assuming they give a nose down input, slightly. They reduce attitude to level off, reduce thrust to maintain speed and the nose attitude reduces further due to the power/pitch couple. To apply some nose down trim when a few seconds later you are likely to apply the very opposite due to thrust reduction seems to be an odd technique and not one I would encourage. It is flying pitch on trim and not elevator. This is normally considered a No No. Have I misunderstood?
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Old 9th Apr 2016, 12:31
  #1155 (permalink)  
 
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Originally Posted by portmanteau View Post
according to 737flightsim.com total stab travel is - 0.2 to +16.9 trim units and 1 degree of stab travel = 1 trim unit. Full scale travel thus = 17.1 units or degrees. Stab is neutral at 4 trim units.
OK, so the flight simmers reckon that 1 unit = 1 degree. Hmmm.

Just running with that, how is it possible to get -5 units of trim then? Did they mean the crew changed the trim by 5 units nose down? I guess that must be it.

So, if the flaps were up, which the FR24 speed profile certainly suggests, then I doubt they would go from typical approach trim values with F30 (say about 7 units) to something 5 units less because the trimmer will stop at just short of 4 units. They would have had to pull the handle and trim manually.

If the flaps were still extended, then they could trim to a little more than 0 units.

In either case, with zero trim with the flaps extended or 4 units of trim with the flaps up, a level attitude still could be still be maintained with effort. It is difficult for me to understand how such a trim value could lead to such an extreme event that would result in an average of 45 degrees nose down pitch and 320kts. With 4 units of trim, flaps up and 320kts and no pressure on the control column, the aircraft would surely not be in such an extreme attitude.
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Old 9th Apr 2016, 14:53
  #1156 (permalink)  
 
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http://https://www.rt.com/news/338898-flydubai-crash-records-nosedive/

If this is correct, we are looking at a completely disorientated crew, or possibly a pilot incapacitation that was not detected fast enough.
Both had pregnant wifes, so I don't think this was a deliberate action.
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Old 9th Apr 2016, 17:24
  #1157 (permalink)  
 
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https://www.youtube.com/watch?v=mPhOChy4bQs

Trying to reconstruct in a simulator
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Old 9th Apr 2016, 17:25
  #1158 (permalink)  
 
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Originally Posted by Capn Bloggs View Post
If there is a lot of forward force required on the control column it is a "natural" reaction to use the trim to help.
The operative word is "simultaneous". This means both forward push on control column and nose down trim occurred together at the same time. Given manual command of the control column I cannot see how manual pitch trim could have been applied at the same time. This therefore only leaves the STS to automatically follow the manual control column command.
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Old 9th Apr 2016, 17:52
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For what it's worth, I happened to find myself in the (B738) sim today and therein, with some time to spare at the end of the session, I endeavoured to reproduce one likely go-around scenario which that crew might have encountered,... and let's just say that my (fairly benign) experiment ended up with the sim entering a steep dive (>40 nose down), with the speed increasing rapidly (even with the thrust levers closed, nudging 270 Kts when we hit the ground), and all the while I had the control column buried hard back in to my (admittedly a fairly expanded) waistline whilst trying to get the nose to come up, and during which I was pulling as hard as I could on the yoke, with both arms (and I'm not exactly weak), but which didn't work (i.e. the nose would not come up, even with full aft control column)... the resultant outcome of which was that we speared into the ground in an almost uncannily similar manner. It was certainly sobering stuff, and, yes, there were a couple of things I maybe could have done to get the nose-up (but, for the sake of the experiment, I didn't... veritably trying to emulate a possibly overwhelmed and tired / fatigued crew). In summary, the B737 can be a real handful in a go-around and, imho & experience, the two engine go-around has typically been badly taught & executed in every airline that I've ever been in (and I've been in more than a few!)... and I'd go so far as to say that the 2x engined go-around on the B737 is typically the most f'ked-up manoeuvre of all possible manoeuvres; though it shouldn't be, but it often is!

Last edited by Old King Coal; 10th Apr 2016 at 01:14. Reason: To keep the spelling police (chuks) off my back... (happy now chuks?) !
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Old 9th Apr 2016, 17:56
  #1160 (permalink)  
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OKC, sobering indeed, how'd you do it? Can you specify the control and engine settings that produced the dive and absence of response to elevator input? What was the stab setting just prior to the uncontrolled descent?

I've seen numerous g/a's in flight data and they're all safely flown. I'm sure many are interested in how you obtained this outcome. Thanks! PJ2
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