AF 447 Thread No. 10
Originally Posted by Lonewolf_50
CVR time tags indicate about 2:10 AM to about 2:14 AM as "when" this happened.
Originally Posted by Lonewolf_50
I presume the former.
Originally Posted by Lonewolf_50
Probably thinking "why's it doing that?" or "Why isn't it doing what I expect it to do?"
Originally Posted by Lonewolf_50
There were reasons for some of what they did, hence a rational thought process, but those reasons seem to have been based on faulty diagnosis of their problem, faulty recall of procedures, and faulty flying skills, and faulty CRM technique.
Originally Posted by Lonewolf_50
In the last minute, maybe so, but in the first three, confused more than panic stricken ...
Originally Posted by PJ2
Yes, it's not consistent certainly but merely "mostly in the direction of..."
Originally Posted by Dozy Wannabe
Not sure I agree with the first sentence - if HA manual handling was taught as part of basic conversion training, then there would have been a reinforced mnemonic inside the F/Os' heads that pulling up to that extent in the cruise is a very bad idea. As are large control inputs in general.
Originally Posted by BEA report, page 87
Case of TAM flight on 12 November 2003
This case, which happened to an A330-200, was not one of the thirteen events studied
above because no crew report was available. However, in the light of the data from
flight AF 447, it seems useful to mention it. In fact, following icing of at least two
Pitot probes at FL360, the crew made some high amplitude flight control inputs (to
the stop), sometimes simultaneously. When the AP disengaged, both pilots made
pitch-up inputs (one went to the stop) that resulted in an increase in pitch of 8°. On
several occasions, the stall warning was triggered due to the nose-up inputs, and the
crew reacted with strong pitch-down inputs. During the 4 minutes that the sequence
lasted, the load factor varied between 1.96 g and -0.26 g, the pitch attitude reached
13° nose-up and the angle of attack reached 10°. Altitude variations, however, were
less than 600 ft.
This case, which happened to an A330-200, was not one of the thirteen events studied
above because no crew report was available. However, in the light of the data from
flight AF 447, it seems useful to mention it. In fact, following icing of at least two
Pitot probes at FL360, the crew made some high amplitude flight control inputs (to
the stop), sometimes simultaneously. When the AP disengaged, both pilots made
pitch-up inputs (one went to the stop) that resulted in an increase in pitch of 8°. On
several occasions, the stall warning was triggered due to the nose-up inputs, and the
crew reacted with strong pitch-down inputs. During the 4 minutes that the sequence
lasted, the load factor varied between 1.96 g and -0.26 g, the pitch attitude reached
13° nose-up and the angle of attack reached 10°. Altitude variations, however, were
less than 600 ft.
Originally Posted by gums
So the jet "appears" to be a pitch attitude command, and the turn implementation appears to also allow for the gee involved to maintain both the established pitch AND roll. We all know that 60 degrees of bank requires 2 gees, and so forth, huh?
What kind of algorithm would system that actively chases 1G use to cope with bank? Pitch? Turbulence? Maintaining the inertially derived flightpath elegantly solves all these problems and fits well stable and quite unmaneuverable machine whose raison d'ętre is to carry passengers from A to B economically and safely and not to shoot down or bomb anyone in the process.
Anyway, pilots absolutely need not to be aware of all the intricacies of the FBW all the time as aeroplane's response is strictly conventional. Pushing the stick moves the nose down, pulling it left rolls the wings left and vice versa. If the aeroplane doesn't respond, you have truly messed up and better quickly figure out what is going on and how to unmess yourself.
Originally Posted by gums
How one can assert the jet is a pitch attitude control law still bothers me.
Originally Posted by gums
Further, my understanding of aero is that a straight mechanical system that we had long ago, and in some jets to this day, you trim for AoA, not gee, not attitude, not speed.
Originally Posted by Lonewolf_50
Last of all, if like most pilots you are initially taught the above forumula, and imbed that relationship first, how many reps of a different conceptual approach do you need in order to fly "G" or "flight path" rather than pitch using your hands and feet, and internalize that?
Originally Posted by Lonewolf_50
Are they wrong to do so, since the plane as designed isn't meant (under the Normal condition) to fly attitude but rather flight path?
Originally Posted by bubbers44
It never happened in my era.
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Agreed - substitute "large" with "large and sustained" in my original post.
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TurbineD
What of the Report's mention of "machine" shortcomings, that may have exacerbated the crash's entry? No AoA, Stick invisibility, etc. ?
"It wasn't the airplane that caused this..."
What of the Report's mention of "machine" shortcomings, that may have exacerbated the crash's entry? No AoA, Stick invisibility, etc. ?
"It wasn't the airplane that caused this..."
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What's your definition of "real pilot", bubbers?
If you mean pre-FMS/"magenta line", then as Clandestino has pointed out this has happened before to an old-school crew on a NWA B727.
As far as we can tell from the CVR, the PF never really fully appreciated the situation and at least for some of the time had (wrongly) convinced himself that they were in an overspeed situation. On any other day he may not have made that mistake, but on this occasion he did. This implies that his emotions and instinct overruled his rational thought processes, but it does not mean that he was an incompetent pilot.
You can be considered the premier pilot in your airline and still make mistakes - Tenerife proved that.
If you mean pre-FMS/"magenta line", then as Clandestino has pointed out this has happened before to an old-school crew on a NWA B727.
As far as we can tell from the CVR, the PF never really fully appreciated the situation and at least for some of the time had (wrongly) convinced himself that they were in an overspeed situation. On any other day he may not have made that mistake, but on this occasion he did. This implies that his emotions and instinct overruled his rational thought processes, but it does not mean that he was an incompetent pilot.
You can be considered the premier pilot in your airline and still make mistakes - Tenerife proved that.
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A real pilot doesn't let automation override his basic flying skills. A real pilot can recover from a stall quite easilly without the aid of a FD. A real pilot knows what his aircraft is capable of doing at high altitude and what it is not capable of doing. Real pilots usually don't end up in the newspaper because they did something incredibly stupid. I guess real pilots also remember the days when you knew how to swing a prop to start an aircraft with no battery installed. Maybe I am just getting old but the new brand of pilots flying the magenta line seem to have not learned the basic skills we all grew up with.
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As far as we can tell from the CVR, the PF never really fully appreciated the situation and at least for some of the time had (wrongly) convinced himself that they were in an overspeed situation. On any other day he may not have made that mistake, but on this occasion he did. This implies that his emotions and instinct overruled his rational thought processes, but it does not mean that he was an incompetent pilot.
That is also the date they were having a bad day?
Three have a bad day at the same time and same place
Bonin going viral?
A challenge to the statistics?
Last edited by jcjeant; 7th Mar 2013 at 10:27.
PJ2: thanks for taking the time on that reply. Very well answered, I am. 
Clandestino: body clock adjustment points noted.
Is this in all laws other than direct?
Clandestino: body clock adjustment points noted.
Pilot flies the attitude and FBW makes his job easier by maintaining the flightpath, what you basically get is FBW automatically compensating for
turbulence.
turbulence.
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Quote:
Pilot flies the attitude and FBW makes his job easier.......
Pilot flies the attitude and FBW makes his job easier.......
If so, should AOA be readily available? If not, should one depend on FD?
If FD is selected OFF, (as it would be post UAS), what then? PITCH?
That might be just the wrong cue....
Last edited by Lyman; 7th Mar 2013 at 16:25.
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AoA
Pitch attitude equals AoA in level flight. Otherwise it does not.
Flying pitch and power causes the airplane to acquire a stable condition of airspeed, flight path angle and AoA. Flying AoA causes the airplane to enter into an oscillary motion known as a 'phugoid' .
Originally Posted by Lyman
Isn't "flying attitude" the same as flying Angle of Attack?
Flying pitch and power causes the airplane to acquire a stable condition of airspeed, flight path angle and AoA. Flying AoA causes the airplane to enter into an oscillary motion known as a 'phugoid' .
Last edited by HazelNuts39; 7th Mar 2013 at 17:07.
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Yes, thanks. In the case of 447, in an unusual climb, and even before, during the first STALL WARNING, AoA and PITCH were discrepant. STALL functions from the AoA vanes, could the pilot have rejected this warning as false (it was not) for that reason?
A severe updraft, or other unexpected event could disorient a crew at a very inopportune time.....Or set the stage for a mistrust of the STALL system....
For that matter, an inaccurate or even erroneous AoA reading could trigger a protection, the aircraft is not invulnerable, (uncommanded climb).
And thank you for the Phugoid reminder. I have believed from the start that the Pilots were having a time with altitude. Whatever the PF saw, and to a lesser extent the PM, what are the possibilities of a PITCH phugoid, either real, or sensate? Such that a chronic climb derived from incorrect input?
Rhetorical, if you like....
A severe updraft, or other unexpected event could disorient a crew at a very inopportune time.....Or set the stage for a mistrust of the STALL system....
For that matter, an inaccurate or even erroneous AoA reading could trigger a protection, the aircraft is not invulnerable, (uncommanded climb).
And thank you for the Phugoid reminder. I have believed from the start that the Pilots were having a time with altitude. Whatever the PF saw, and to a lesser extent the PM, what are the possibilities of a PITCH phugoid, either real, or sensate? Such that a chronic climb derived from incorrect input?
Rhetorical, if you like....
Last edited by Lyman; 7th Mar 2013 at 17:13.
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what are the possibilities of a PITCH phugoid, either real, or sensate? Such that a chronic climb derived from incorrect input?
Last edited by Owain Glyndwr; 7th Mar 2013 at 18:55.
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Most people think of aircraft stability as being the behaviour of the machine left to itself, not gyrations produced by random pilot inputs. The fact that the flight path varied has nothing to do with any considerations of phugoid stability.
Originally Posted by Lyman
For that matter, an inaccurate or even erroneous AoA reading could trigger a protection, the aircraft is not invulnerable, (uncommanded climb).
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Owain Glyndwr
Like spelling that name, Welsh?
Busy with Roll, and probably not ruddering, the PF had Yaw, Roll and Pitch excursions whilst trying to sort the original eight degree right wing low.
The Pitch was not reliable, by definition, it and gee were not consistent, nor was Vario or much of anything, right after a veryunexpected event.
I think because so much was made of the Roll Direct problem he had, people forget it was Pitch that did them in.
Forget Phugoid, my bad, call it PIO in combination with Roll PIO.
Thanks. Much obliged
Like spelling that name, Welsh?
Busy with Roll, and probably not ruddering, the PF had Yaw, Roll and Pitch excursions whilst trying to sort the original eight degree right wing low.
The Pitch was not reliable, by definition, it and gee were not consistent, nor was Vario or much of anything, right after a veryunexpected event.
I think because so much was made of the Roll Direct problem he had, people forget it was Pitch that did them in.
Forget Phugoid, my bad, call it PIO in combination with Roll PIO.
Thanks. Much obliged
Originally Posted by Lonewolf_50
Is this in all laws other than direct?
Originally Posted by Lyman
what are the possibilities of a PITCH phugoid
Originally Posted by Green's Law of Debate
Anything is possible if you don't know what you're talking about.
Originally Posted by Lyman
Forget Phugoid, my bad, call it PIO in combination with Roll PIO.
Last edited by Clandestino; 7th Mar 2013 at 20:00.
Hey, Lyman!
OG, Nuts, PJ and Cland are onto something.
1) Although phugoid mode exists for normal planes, the FBW systems negate it. They are contantly attempting to maintain an attitude or gee. The bus mixes both.
2) Cland mentioned the turbulence a few posts ago. Right on! At low altitude over the desert, with all the thermals and such, our little jet felt like a 757 or something. The system reacted to the up and down quicker than we could - very smooth ride.
3) Only FBW system I know of that uses AoA for trim is the Viper when the gear is down. The 'bus uses pitch attitude a lot more than we did ( we used it ZERO!!!). Could be the Hornet and Raptor and Lightning and Tiffie have a similar control law with gear down. But I an't find any AoA bias for the 'bus unless the sucker is about to get into a stall.
We may discuss the fine points about the control laws and the implementation, but the cause of the crash was a crew problem. Some misunderstanding about the finer points about the control laws may have added to the confusion, but just that.
And thats what this pioneer in FBW jets has to say.
OG, Nuts, PJ and Cland are onto something.
1) Although phugoid mode exists for normal planes, the FBW systems negate it. They are contantly attempting to maintain an attitude or gee. The bus mixes both.
2) Cland mentioned the turbulence a few posts ago. Right on! At low altitude over the desert, with all the thermals and such, our little jet felt like a 757 or something. The system reacted to the up and down quicker than we could - very smooth ride.
3) Only FBW system I know of that uses AoA for trim is the Viper when the gear is down. The 'bus uses pitch attitude a lot more than we did ( we used it ZERO!!!). Could be the Hornet and Raptor and Lightning and Tiffie have a similar control law with gear down. But I an't find any AoA bias for the 'bus unless the sucker is about to get into a stall.
We may discuss the fine points about the control laws and the implementation, but the cause of the crash was a crew problem. Some misunderstanding about the finer points about the control laws may have added to the confusion, but just that.
And thats what this pioneer in FBW jets has to say.
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The flight path was not constant because of the 11 degree pull up. If they had held a constant 2 degrees nose up attitude they would have been fine holding altitude with a good altimiter.