B-738 Crash in Russia Rostov-on-Don
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
The pitch down is the more probable scenario due both to somatographic illusion and the requirement to trim forward as the aircraft accelerates away from the low energy approach config.
Join Date: Dec 2013
Location: Paso Robles
Posts: 261
Likes: 0
Received 0 Likes
on
0 Posts
The illusion scenario is so so very unlikely -
Last edited by porterhouse; 3rd Apr 2016 at 08:12.
Join Date: Feb 2005
Location: Finsbury Park
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Sciolistes
Somatographic illusion is only one possibility, not necessarily the answer, but it is a well known phenomenon and with the power pitch couple it may cause the crew to either push forward on the control column or trim nose down or both. I'm not sure why you feel it is unlikely.
The subsequent low nose attitude and presumed high power setting would cause the aircraft to accelerate very rapidly giving the illusion of a pitch up, If the crew pulled the power back, this would make the aircraft pitch down even harder and given the extreme low nose attitude, the PFD would not look familiar to the crew and the pitch attitude would look unusual, the crew may therefore have relied on seat of the pants instinct and reacted to what they felt instead of using the information presented.
Flight simulators cannot replicate the somatographic effect, but instead, they rely on tilt angles to fool occupants into thinking they are manoeuvring such as accelerating down a runway while remaining firmly bolted to the floor.
There is no doubt that the aircraft was accelerating, very rapidly, toward the ground, as confirmed by the videos and the above mentioned fs24 data, laws of physics again.
I would tend to prefer the known science and lessons learned from the past and am not swayed by the unregulated data supplied by fs24 which seems just to confirm the obvious, eg, the aircraft started to climb, then descended rapidly.
Somatographic illusion is only one possibility, not necessarily the answer, but it is a well known phenomenon and with the power pitch couple it may cause the crew to either push forward on the control column or trim nose down or both. I'm not sure why you feel it is unlikely.
The subsequent low nose attitude and presumed high power setting would cause the aircraft to accelerate very rapidly giving the illusion of a pitch up, If the crew pulled the power back, this would make the aircraft pitch down even harder and given the extreme low nose attitude, the PFD would not look familiar to the crew and the pitch attitude would look unusual, the crew may therefore have relied on seat of the pants instinct and reacted to what they felt instead of using the information presented.
Flight simulators cannot replicate the somatographic effect, but instead, they rely on tilt angles to fool occupants into thinking they are manoeuvring such as accelerating down a runway while remaining firmly bolted to the floor.
There is no doubt that the aircraft was accelerating, very rapidly, toward the ground, as confirmed by the videos and the above mentioned fs24 data, laws of physics again.
I would tend to prefer the known science and lessons learned from the past and am not swayed by the unregulated data supplied by fs24 which seems just to confirm the obvious, eg, the aircraft started to climb, then descended rapidly.
Join Date: Aug 2008
Location: Betwixt and between
Posts: 666
Likes: 0
Received 0 Likes
on
0 Posts
Flight simulators cannot replicate the somatographic effect, but instead, they rely on tilt angles to fool occupants into thinking they are manoeuvring such as accelerating down a runway while remaining firmly bolted to the floor.
Something else happened.
Join Date: May 2012
Location: Virginia
Posts: 9
Likes: 0
Received 0 Likes
on
0 Posts
Hello again,
I was tinkering with acceleration vectors derived from the FR24 provided ADS-B data... a fearsome endeavor on several fronts!
Using these, I took a first stab at the ascent angle the crew of FZ981 might have felt (which could be completely wrong as I am way out of my league as a meteorologist trying to calculate an aviator's somatogravic illusion -- nothing could go wrong with that!
).
My methodology:
-- calculate the plane's ascent angle (simple right angle triangle trig) using the vertical and horizontal velocities (I created a second vert. velocity set which used the gps altitude changes in the last few seconds as the VV reported look to be off (I could speculate as to why, but that would be a different post)
-- calculate vert and horiz accel based on changing vert and horiz velocities.
-- add gravity (9.8 m/s) to the vert. accel
-- calculate the acceleration vector (as well as the not shown magnitude) based on H&V accel such that 90deg equals no aircraft accel, and 1g of fwd (and level) accel equals 45deg. (for example only)
-- Pitch illusion I estimated as: (90deg - AccelAngle + AscentAngle). I estimated this based on the lower of the two plots on this chart from the AIB:
I would not be shocked if I made one or more boneheaded mistakes, and would be more than happy to fix them. I would be happy to share my excel worksheets.
I hope this is helpful,
Jacob
I was tinkering with acceleration vectors derived from the FR24 provided ADS-B data... a fearsome endeavor on several fronts!
Using these, I took a first stab at the ascent angle the crew of FZ981 might have felt (which could be completely wrong as I am way out of my league as a meteorologist trying to calculate an aviator's somatogravic illusion -- nothing could go wrong with that!
).My methodology:
-- calculate the plane's ascent angle (simple right angle triangle trig) using the vertical and horizontal velocities (I created a second vert. velocity set which used the gps altitude changes in the last few seconds as the VV reported look to be off (I could speculate as to why, but that would be a different post)
-- calculate vert and horiz accel based on changing vert and horiz velocities.
-- add gravity (9.8 m/s) to the vert. accel
-- calculate the acceleration vector (as well as the not shown magnitude) based on H&V accel such that 90deg equals no aircraft accel, and 1g of fwd (and level) accel equals 45deg. (for example only)
-- Pitch illusion I estimated as: (90deg - AccelAngle + AscentAngle). I estimated this based on the lower of the two plots on this chart from the AIB:
I would not be shocked if I made one or more boneheaded mistakes, and would be more than happy to fix them
. I would be happy to share my excel worksheets.I hope this is helpful,
Jacob
Join Date: Feb 2005
Location: Finsbury Park
Posts: 10
Likes: 0
Received 0 Likes
on
0 Posts
Something else happened.
Your presumption would be correct. IMHO
I remember the days of flying a PC check and the only time you would use the auto pilot was when the instructor/check airman was reloading glitches in the simulator.
If you could fly those simulators by hand, you could fly the plane by hand.
It is possible that the guys in this accident had lost some skills by using the automation so much.
Manual go-arounds are probably barely practiced these days in the sim.
Regards,
OBD
I remember the days of flying a PC check and the only time you would use the auto pilot was when the instructor/check airman was reloading glitches in the simulator.
If you could fly those simulators by hand, you could fly the plane by hand.
It is possible that the guys in this accident had lost some skills by using the automation so much.
Manual go-arounds are probably barely practiced these days in the sim.
Regards,
OBD
My employer uses the same configuration (HGS). All Go Arounds are hand flown. In the Sim, and in the aircraft. My point is this; The 737 not equipped with Autoland requires a manually flown Go Around. If the Autopilot is off during the approach, then the Go Around will be hand flown without auto throttles.
Join Date: Apr 2009
Location: Oakland, CA
Age: 72
Posts: 427
Likes: 0
Received 0 Likes
on
0 Posts
How in God's name can both pilots in a low authority gradient flight deck suddenly become so disorientated
Re, "how in God's name...", etc.,
As Sid Dekker writes in his, The Field Guide to Understanding Human Error, "What [we] think should have happened does not explain people's behaviour.", (Ch.5, p.39, Ashgate 2006)
As Sid Dekker writes in his, The Field Guide to Understanding Human Error, "What [we] think should have happened does not explain people's behaviour.", (Ch.5, p.39, Ashgate 2006)
It can be incredibly difficult to interpret a HUD in a rapidly changing unusual attitude. I sim instruct on a HUD equipped military type, and the first action on disorientation is to transfer to head down (conventional) instruments. Has the civil world taken on this advice when it started to get HUDs?
Timelord - yes, it is strongly advised for the reason you state.
Join Date: Oct 2010
Location: EASA land
Posts: 27
Likes: 0
Received 0 Likes
on
0 Posts
SOP changes needed ?
I think that SOPs need to be changed in order to avoid the repeated crashes after go around. Crash sequence begins with the extreme uncontrolled nose up pitch angle which is spotted too late and overcontrol of the the nosedown correction resulting in extreme nose down dive at low altitude.
The SOP change attempting to break this chain is as follows:
At Take off at the Vr Speed the PNF announces "Rotate XX" (XX being number of degrees eg. Rotate 14).
So on take off it is just one word more added to SOPs.
At Go Around situation the PF announces his intentions with words "Go Aroud" and commands some configuration change eg : "Go Around Flaps 11" so the PNF knows what is going on and what is expected from him at that time.
The PNF then announces "Rotate XX" (Again the XX is number of degrees) and then continue as per present SOPs. The same words "Rotate XX" are used in both Take Off and Go Around.
This little addition to the existing SOPs would help fhe pilot flying focus attention on the relevant instrument indication pitch angle which is often neglected by pilots focusing too much attention at the Flight Director or IAS indication.Also the PNF would adjust his attention span to include the pitch angle.
This change would help to reach and maintain the approximate pitch angle required for the initial climb out.
Calling the required pitch on each take off would make it a habit to do the same at the moment of a go around when the aircraft is rotated from approach pitch to the approximate go around pitch angle.
The SOP change attempting to break this chain is as follows:
At Take off at the Vr Speed the PNF announces "Rotate XX" (XX being number of degrees eg. Rotate 14).
So on take off it is just one word more added to SOPs.
At Go Around situation the PF announces his intentions with words "Go Aroud" and commands some configuration change eg : "Go Around Flaps 11" so the PNF knows what is going on and what is expected from him at that time.
The PNF then announces "Rotate XX" (Again the XX is number of degrees) and then continue as per present SOPs. The same words "Rotate XX" are used in both Take Off and Go Around.
This little addition to the existing SOPs would help fhe pilot flying focus attention on the relevant instrument indication pitch angle which is often neglected by pilots focusing too much attention at the Flight Director or IAS indication.Also the PNF would adjust his attention span to include the pitch angle.
This change would help to reach and maintain the approximate pitch angle required for the initial climb out.
Calling the required pitch on each take off would make it a habit to do the same at the moment of a go around when the aircraft is rotated from approach pitch to the approximate go around pitch angle.
Go-around pitch attitudes vary within a very narrow band, usually 12.5 to a max of 20 or a pitch that yields the correct GA airspeed and keeps it there. Go-around pitch attitudes are a part of the certification process and when flown, are safe. There should be no need to specify pitch.
Experience would indicate however, that there is a strong and clear need to make a call when pitch or speed are either above or below SOP limits.
FDM Programs should be able to help trend what kind of GA performance an air carrier is getting from its pilots, and train accordingly.
Also, go-arounds from altitude, (not at/near minima) require slightly different handling, and a pitch attitude appropriate to the circumstances, not an "SOP-specific" pitch attitude. Here again a call-out is already mandatory in SOPs when any parameter is beyond SOP tolerances.
Experience would indicate however, that there is a strong and clear need to make a call when pitch or speed are either above or below SOP limits.
FDM Programs should be able to help trend what kind of GA performance an air carrier is getting from its pilots, and train accordingly.
Also, go-arounds from altitude, (not at/near minima) require slightly different handling, and a pitch attitude appropriate to the circumstances, not an "SOP-specific" pitch attitude. Here again a call-out is already mandatory in SOPs when any parameter is beyond SOP tolerances.
I don't like a mandated call out of X degrees. What if I don't want to fly 15 degrees for a valid reason ? A much better idea would be to recognise that as an Industry we are training more subjects in a shorter space of time to candidates with less hand flying experience, and to allow for the new/extra sunjects in our training system. ( an annual handling sim?) In addition to appropriate levels of recurrent training, legislating to respect a pilots circadium rhythm to some degree when building rosters is also necessary. Mandating another word isn't addressing the problems, it is showing a lack of understanding about why Air Transport is generally safe.
I agree with Framer and PJ2; an extra "pitch" call is not required. Aeroplanes should not be flown by mouth. The crux of the matter under discussion is that pilots sometimes can no longer fly the required manoeuvre, which is, get the nose up and control the speed with pitch until leveloff, then control altitude with pitch and speed with throttles (if the ATS isn't doing it). Simple stuff, really. The more bandaids we put on (eg more standard calls) the more we are merely covering up the underlying problem and eventually making it worse.
As an aside, the "Go Round" call is an FMA readout, not a call of intent. A call of intent would be "Going Around".
As an aside, the "Go Round" call is an FMA readout, not a call of intent. A call of intent would be "Going Around".
I hope "TOGA Tap" picks up on the feedback regarding the suggestion, offered 'as intended' - the suggestion shows some thought about the problem, which is always to be encouraged, particularly today where thought and airmanship appears all but discouraged in favour of auditable training and standards results instead of thinking like a pilot. There is an aspect of mentorship here that I hope is not missed.
That is a very good point PJ.
The kind of maturity required to hold that view point, combined with significant Air Transport Command experience, is what is required at Regulator level and board level in order to see any meaningful change.
(nb I don't profess to have either of the requirements but am working on it
)
The kind of maturity required to hold that view point, combined with significant Air Transport Command experience, is what is required at Regulator level and board level in order to see any meaningful change.
(nb I don't profess to have either of the requirements but am working on it
)
Join Date: Jan 2008
Location: Around the corner
Posts: 171
Likes: 0
Received 0 Likes
on
0 Posts
Airbus training in Toulouse does not train pitch and power at all in their syllabus.
They are very much FDs and Bird dependent. They also do not teach unusual attitude recovery. They only introduced stal recovery into their manuals after AF447 crash. Until than it was not thought at all. But I thought that the Boeing group training was much better as Boeing is not such a forgiving machine as an airbus with its protections. I am starting to realize that the airlines inability to teach basic "pitch and power equals performance" is a wide spread phenomenon through all airlines and types. Having said that, I have met few capable instructors in my flying carrier, who could teach the basics. But most airlines brush basic training off with the words, "They are airline pilots, they must know how to fly".
If pilots do not have basic scanning ability and in all their manual flying they only follow flight directors, while not seing through it the actual performance, how can we expect these
pilots, who were not exposed to proper training for years, to perform well while they are under stress, tired and at night? If the heads up display flight directors show them to dive down due to basting altitude constrain, of course they will blindly follow it. They are used to flight directors showing them the way. Flight director is the real PIC on the aircraft.
With few exception, every sim I teach, I have to revert to teaching basic attitude flying. I disregard the rest of syllabus until people can fly. And they usually improve quickly and within one hour they are proficient. But why am I the only guy as far as I know, who does that? Could somebody else incourage me and tell me they also teach basic raw data flying in airlines? Why do we constantly keep repeating the mantra: Fly Navigate And Communicate but do not teach flying skills? Why do most airline pilots who start to criticise me do not know the difference of scanning ability required for Raw data with FDs off and Authotrust off" as opposed to following flight directors with autothrust on? Those who are the once saying pilots must know how to fly are usually the once who cannot do it. And they usually take it out of the syllabus as they are the management.
They are very much FDs and Bird dependent. They also do not teach unusual attitude recovery. They only introduced stal recovery into their manuals after AF447 crash. Until than it was not thought at all. But I thought that the Boeing group training was much better as Boeing is not such a forgiving machine as an airbus with its protections. I am starting to realize that the airlines inability to teach basic "pitch and power equals performance" is a wide spread phenomenon through all airlines and types. Having said that, I have met few capable instructors in my flying carrier, who could teach the basics. But most airlines brush basic training off with the words, "They are airline pilots, they must know how to fly".
If pilots do not have basic scanning ability and in all their manual flying they only follow flight directors, while not seing through it the actual performance, how can we expect these
pilots, who were not exposed to proper training for years, to perform well while they are under stress, tired and at night? If the heads up display flight directors show them to dive down due to basting altitude constrain, of course they will blindly follow it. They are used to flight directors showing them the way. Flight director is the real PIC on the aircraft.
With few exception, every sim I teach, I have to revert to teaching basic attitude flying. I disregard the rest of syllabus until people can fly. And they usually improve quickly and within one hour they are proficient. But why am I the only guy as far as I know, who does that? Could somebody else incourage me and tell me they also teach basic raw data flying in airlines? Why do we constantly keep repeating the mantra: Fly Navigate And Communicate but do not teach flying skills? Why do most airline pilots who start to criticise me do not know the difference of scanning ability required for Raw data with FDs off and Authotrust off" as opposed to following flight directors with autothrust on? Those who are the once saying pilots must know how to fly are usually the once who cannot do it. And they usually take it out of the syllabus as they are the management.
