AF 447 Thread No. 7
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CONF iture;
Strange, my version of PJ2's post reads:
The other strange thing about it is that per S/W schedule (the ADR's were turned back on after the stall) the warning should stop at 6.1 deg AoA for M.658. OTOH the flight path angle for the airspeed and VSI is 9.8 deg down.
Strange, my version of PJ2's post reads:
At FL245 the stall warning stopped 40 seconds after it began, the AoA was 10degND, M0.658, VSI 7000fpm down, CAS 278kts.
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I don't know about the S/W system, but I do know, per BEA, that the A/S bug for S/W is absent from the speed tape when all ADRs are AWOL.
"..this marker disappears..."
HazelNuts39...."Another strange thing..." Keep them coming, I relish strange things, especially if they are not crew actions....
"..this marker disappears..."
HazelNuts39...."Another strange thing..." Keep them coming, I relish strange things, especially if they are not crew actions....
Thanks HN39...the FPV symbol was 10deg below the line dividing blue and brown on the PFD, which to me indicated an AoA of roughy +10deg while the aircraft was still descending rapidly, so it was my clumsy writing even though I think the meaning came through for most others. On the stall warning, in fact the first exercise there was no such warning because we had all the ADRs off, then on for the FPV later - we did it again using a different failure method to get the sim into Alt 2...these are details behind the larger exercise but technically correct - my posts are almost always too long as it is - PJ2
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PJ2;
Thanks for contributing your valuable exercise to the discussion. I was wondering: Do you have to rely on your notes and memory, or does the sim have a facility for recording the flight, e.g. for a post-flight debrief between instructor and pupil?
Thanks for contributing your valuable exercise to the discussion. I was wondering: Do you have to rely on your notes and memory, or does the sim have a facility for recording the flight, e.g. for a post-flight debrief between instructor and pupil?
HN39;
First, I debated long and hard on a decision to contribute the sim experience at all, and not for the obvious reasons of potential misunderstanding etc,...it was a personal exercise with colleagues who in one case are equally interested and who are in a good position to teach others who fly this aircraft and in another case those who for other reasons are interested in the outcomes. But the more I read from the current discussion the greater some contribution seemed to be of value especially since at least two other experiences have been noted. I wanted to give a sense of the event from initial loss of airspeed through the pitch-up/apogee and holding the stick back so the stall was truly "set", and then the recovery characteristics. It is by no means definitive but I think it is sufficient.
The sim has the ability to record its traces. However, arrangements like these are almost always ad-hoc and time for preparation is at a premium with training schedule demands and hours of availability and coordinating with the technicians to obtain materials after is for various reasons an uncertain process.
There isn't time for note-taking in the moment but other recording methods were used. Still photos from an earlier session were helpful but are not complete nor do they give a sense of situation. Videoing is more helpful but doing it well requires close coordination and ideal circumstances; - covering all instruments and in a timely/relevant way is a challenge!
In my non-engineering view, the sim "behaved" as I expected the airplane might. I don't have experience with the Cooper-Harper scale although I am familiar with it and my own characterizations of the airplane were probably generous. The warning and cautions which accompanied the CAS and ADR failures were less distracting than I had anticipated. The loss of two hydraulic systems or the Emergency Electrical configuration is vastly more complex, demanding and challenging for a two-pilot crew. I don't know how to post audio files, (except through links to YouTube - SoundCloud doesn't provide links) just to demonstrate what the Stall warning sounds like but it was hard to ignore. Also, it was not possible to set aside hindsight so it was not possible to be "confused" by the various behaviours.
First, I debated long and hard on a decision to contribute the sim experience at all, and not for the obvious reasons of potential misunderstanding etc,...it was a personal exercise with colleagues who in one case are equally interested and who are in a good position to teach others who fly this aircraft and in another case those who for other reasons are interested in the outcomes. But the more I read from the current discussion the greater some contribution seemed to be of value especially since at least two other experiences have been noted. I wanted to give a sense of the event from initial loss of airspeed through the pitch-up/apogee and holding the stick back so the stall was truly "set", and then the recovery characteristics. It is by no means definitive but I think it is sufficient.
The sim has the ability to record its traces. However, arrangements like these are almost always ad-hoc and time for preparation is at a premium with training schedule demands and hours of availability and coordinating with the technicians to obtain materials after is for various reasons an uncertain process.
There isn't time for note-taking in the moment but other recording methods were used. Still photos from an earlier session were helpful but are not complete nor do they give a sense of situation. Videoing is more helpful but doing it well requires close coordination and ideal circumstances; - covering all instruments and in a timely/relevant way is a challenge!
In my non-engineering view, the sim "behaved" as I expected the airplane might. I don't have experience with the Cooper-Harper scale although I am familiar with it and my own characterizations of the airplane were probably generous. The warning and cautions which accompanied the CAS and ADR failures were less distracting than I had anticipated. The loss of two hydraulic systems or the Emergency Electrical configuration is vastly more complex, demanding and challenging for a two-pilot crew. I don't know how to post audio files, (except through links to YouTube - SoundCloud doesn't provide links) just to demonstrate what the Stall warning sounds like but it was hard to ignore. Also, it was not possible to set aside hindsight so it was not possible to be "confused" by the various behaviours.
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Originally Posted by HN39
Strange, my version of PJ2's post reads:
Originally Posted by PJ2
Have you any thoughts on the altitude required to recover from the full stall? What was your experience in your own experiment?
I was certainly impressed by the amplitude of negative pitch required to silent the stall warning. Not much blue sky left on the PFD. We, airline pilots, are simply not used to command such attitudes.
CONF iture, Re, "I was certainly impressed by the amplitude of negative pitch required to silent the stall warning. Not much blue sky left on the PFD. We, airline pilots, are simply not used to command such attitudes. "
No kidding...not much blue left at all. And the AoA crept up - it didn't just change right away. The last bit from around 20deg to 10 seemed to go a bit faster.
No kidding...not much blue left at all. And the AoA crept up - it didn't just change right away. The last bit from around 20deg to 10 seemed to go a bit faster.
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PJ2;
In AF447 pressure errors developed in the pitot/static system as the AoA exceeded approx. 25 deg, causing the IAS to drop rapidly, to below 60 kt at about 41 deg AoA. I gather that AoA in your exercises did not exceed 40 deg enough to silence the stall warning, but did you by any chance observe a rapid drop in IAS between 25 and 40 deg AoA?
In AF447 pressure errors developed in the pitot/static system as the AoA exceeded approx. 25 deg, causing the IAS to drop rapidly, to below 60 kt at about 41 deg AoA. I gather that AoA in your exercises did not exceed 40 deg enough to silence the stall warning, but did you by any chance observe a rapid drop in IAS between 25 and 40 deg AoA?
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Sim Limitations
Upset Recovery in Sims | AVIATION WEEK
I do think this article touches on very interesting observations that may have direct or indirect association with AF447 crew behavior. I will let the article speak for itself.
I do think this article touches on very interesting observations that may have direct or indirect association with AF447 crew behavior. I will let the article speak for itself.
@ PJ and 'nuts
Yeah the long response bothers/surprises me, too.
Knowing what we do now, I guess we could "cheat" and crank that THS to the other end to help the pitch moment. Unlike the Viper, the AF jet had a decent cee gee at the time of the incident.
Seems that Doze also tried a recovery in the sim, that right Doze? We need a refresher of your findings.
@RR
I sure hope the human factors is given attention in the findings and recommendations. I still fault the crew, but I empathize with them to some extent due to the warnings and displays they dealt with.
My civilian job was designing and implementing crew displays, and secondly weapon control algorithms to be implemented in part by the crew and mostly by the confusers. Think JDAM, AMRAAM, Maverick, Hellfire, Harpoon, etc.
I also think a HUD would have helped immensely, as the FPM would have been at the bottom of the display even tho the pitch attitude was nose high. Being a HUD-a-holic since 1971, I simply loved that display. Being far-sighted, I didn't have to squint to read the steam gauges on a serious instrument approach.
Yeah the long response bothers/surprises me, too.
Knowing what we do now, I guess we could "cheat" and crank that THS to the other end to help the pitch moment. Unlike the Viper, the AF jet had a decent cee gee at the time of the incident.
Seems that Doze also tried a recovery in the sim, that right Doze? We need a refresher of your findings.
@RR
I sure hope the human factors is given attention in the findings and recommendations. I still fault the crew, but I empathize with them to some extent due to the warnings and displays they dealt with.
My civilian job was designing and implementing crew displays, and secondly weapon control algorithms to be implemented in part by the crew and mostly by the confusers. Think JDAM, AMRAAM, Maverick, Hellfire, Harpoon, etc.
I also think a HUD would have helped immensely, as the FPM would have been at the bottom of the display even tho the pitch attitude was nose high. Being a HUD-a-holic since 1971, I simply loved that display. Being far-sighted, I didn't have to squint to read the steam gauges on a serious instrument approach.
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AF 447 was avoidable
Airbus is a great NEW technology in the hands of a OLD time pilots, pilots who were not scared of turning the autopilot off very unlike today’s (now everyone can fly) type of pilots who are ok as system/ cockpit managers but not aviators (sky managers) as used to be the case right up until fifteen years ago. The AF 447 tragedy is one proof of the point i’m making. Airline managements /accountants don’t understand this fact and are slowly but surely turning airline flying into a scary proposition. Command rejects from one Airline are finding Captains jobs in smaller budget airlines and are making flying dangerous. The cruise captain concept is flawed too. The un-stallable airplanes are only as good in the hands of well trained pilots with the aptitude for flying not so in the hands of (now everyone can fly) kind of pilots. Like in the old days if you could not handle the throttle and stick effectively nobody would allow you to even look at the left seat. CRM courses have become boring mumbo jumbo and just eyewash. AF 447 was avoidable. Senior pilots of the major airlines (only god can save the smaller operators) have a responsibility in so much as to warn their managements that flying is becoming safer only in theory. Cockpit managers are good until the bells start ringing in the cockpit when only pilots with the aptitude for throttle /stick may save the day.
Many airline managements are counting on the *hope* that tragedies such as these don't happen to them.
As we know the word *hope* does not exist in the flight safety manual.
Many airline managements are counting on the *hope* that tragedies such as these don't happen to them.
As we know the word *hope* does not exist in the flight safety manual.
Last edited by bobdazzle; 3rd Apr 2012 at 01:57.
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AF 447 was a "Canary in the coal mine"?
Hi,
bobdazzle:
The "WHY" will led to "BECAUSE".
Very early (after recorders read) BEA told plane operated as designed.
The creation of Human Factors study group is emblematic.
Let's hope findings could identify trends many are concerned.
OC
Your position imo is not conflicting. Will comment ASAP on that.
Safety is increasing. Due many reasons. Automation is an important one.
bobdazzle:
Airline managements /accountants don’t understand this fact and are slowly but surely turning airline flying into a scary proposition.
The "WHY" will led to "BECAUSE".
AF 447 was avoidable
The creation of Human Factors study group is emblematic.
Let's hope findings could identify trends many are concerned.
OC
Your position imo is not conflicting. Will comment ASAP on that.
Safety is increasing. Due many reasons. Automation is an important one.
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Man-machine interface of F-GZCP
Hi,
After analyzing a paper from June 2009 (below) on UAS
I have some questions:
1) Is it dificult to (fast) detect an UAS? Is it important?
2) Is it important to detect? Why?
3) AF447 crew (PF or PM) identified the UAS?
4) If no, this (fast identification) would be important? (safety could be at risk?)
The quoted text comes indeed from an Airbus SAS Engineering "source"?
Link is:
1st segment: http://aviationtroubleshooting.com.br
2nd: /2009/06/af447-unreliable-speed-by-joelle-barthe.html
Please copy and paste both segments in your browser (without space, check this) The "editing tool" (that ALWAYS inserts the link), sometimes change it causing error in the resulting URL.
(It seems there is a glitch here in PPRuNe "editing" tool.)
Will check.
After analyzing a paper from June 2009 (below) on UAS
I have some questions:
1) Is it dificult to (fast) detect an UAS? Is it important?
Unreliable speed is one of the difficul situations that a pilot has to face. Once the failure has been identified, a procedure, based on pitch angles and thrst settings, will assist the pilot in safely flying the aircraft.
But the main difficulty is to rapidly detect an unreliable speed situation. Reaction time is crucial, since the aircraft may stall and overspeed conditions could cause aircraft damage.
But the main difficulty is to rapidly detect an unreliable speed situation. Reaction time is crucial, since the aircraft may stall and overspeed conditions could cause aircraft damage.
An unreliable speed situatio may be difficult to identify, due to the multiple scenarios that can lead to it. Therefore, training is a key element: indeed the flight crew's ability to rapid detected the abnormal situation, and to correctely handle it, is cricial.
In case of any doubt, the pilot should apply the pitch/thrust memory items, and then refer to the QRH to safely fly the aircraft, and to positively determine the faulty source(s) before eliminating it (them).
In case of any doubt, the pilot should apply the pitch/thrust memory items, and then refer to the QRH to safely fly the aircraft, and to positively determine the faulty source(s) before eliminating it (them).
4) If no, this (fast identification) would be important? (safety could be at risk?)
The quoted text comes indeed from an Airbus SAS Engineering "source"?
Link is:
1st segment: http://aviationtroubleshooting.com.br
2nd: /2009/06/af447-unreliable-speed-by-joelle-barthe.html
Please copy and paste both segments in your browser (without space, check this) The "editing tool" (that ALWAYS inserts the link), sometimes change it causing error in the resulting URL.
(It seems there is a glitch here in PPRuNe "editing" tool.)
Will check.
Last edited by Jetdriver; 5th Apr 2012 at 02:46.
RR, re your post #1234 and your comments, "3) AF447 crew (PF or PM) identified the UAS? , 4) If no, this (fast identification) would be important? (safety could be at risk?) ", if I may, I would like to refer to you my response to Turbine D(Post 1208[/B], where identification and action of a UAS event is discussed from a human factors point of view. I've read the Barthes paper and others on UAS, (the link doesn't seem to work).
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259 Avro Yorks were built, an " un-automated" aircraft, hardly dual-controlled. Between 1942 and 1969 a total of 87 " hull losses" were recorded. (I flew 2000+ hours on type. ( No hull losses !))
Aviation HAD to get safer.
Among the airliner stalls, Aero Mexico DC10 -30 lost 11,000ft. on initial climb before continuing. ( The A/P had been set for a rate of climb not possible when heavy and high.)
W. Caribbean MD82 lacked CRM, (the A/P tried to maintain cruising level when de-icing was selected, reducing thrust. The newish F/O was ignored.)
Reading more about China Air B747SP, I see that their Captains are not allowed to let First Officers do T/Os and landings until the Captain has 1000 hour in command on type. To keep the First Officers in practice extra simulator sessions are given to them, monthly. Is this a good idea, and if so is it done in the West, too ?
( My last session in a Link Trainer was arranged so that I did NDB approaches at two different Middle East airfields with similar patterns. Boxes were ticked, even then!)
Aviation HAD to get safer.
Among the airliner stalls, Aero Mexico DC10 -30 lost 11,000ft. on initial climb before continuing. ( The A/P had been set for a rate of climb not possible when heavy and high.)
W. Caribbean MD82 lacked CRM, (the A/P tried to maintain cruising level when de-icing was selected, reducing thrust. The newish F/O was ignored.)
Reading more about China Air B747SP, I see that their Captains are not allowed to let First Officers do T/Os and landings until the Captain has 1000 hour in command on type. To keep the First Officers in practice extra simulator sessions are given to them, monthly. Is this a good idea, and if so is it done in the West, too ?
( My last session in a Link Trainer was arranged so that I did NDB approaches at two different Middle East airfields with similar patterns. Boxes were ticked, even then!)
Last edited by Jetdriver; 5th Apr 2012 at 02:48.
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Interesting article Tommytoyz. Thanks.
Flight simulators “are ‘virtual aircraft’ and they should not be used to develop techniques at the edges of the flight envelope,” Cautions Capt. Wainwright. Rather, he advises, “Concentrate everyone’s attention on taking action early enough to prevent the occurrence of loss of control.” That advice is echoed by other studies.
Yes Tommytoyz, a good discussion on this under-appreciated fact, thank you.
The question has been raised here before and this is a good contribution to the discussion. Airbus' May 1999 edition of "FAST", (Airbus Technical Digest) discusses this in an article entitled, "Airplane upset recovery: A test pilot's point of view", p.18, elaborating on this caution.
This said, the next question is, what does the simulator do in such circumstances?
Obviously the sim doesn't just quit working so there is the consideration of degree of fidelity and not a question of fidelity itself. The data up to the approach-to-stall is assumed to be accurate.
It has been suggested that while the behaviour is not based upon post-entry-into-the-stall and actual stall data, there remains a certain level of useful replication by extension. The real question is, how much and how useful? The best advice from the AWST article is to train well to recognize and stay out of such extreme circumstances - good advice!, but we have had a number of full-stall accidents over the past seven years or so.
I am (was) a line pilot and am not a test pilot or an engineer so do not wish to tread in these areas without due care, but what seems required for recovery from a full stall in terms of pitch attitude and unstalling the wing from AoA's as seen here does not seem to differ wildly from technical expectations. Discussion?
The question has been raised here before and this is a good contribution to the discussion. Airbus' May 1999 edition of "FAST", (Airbus Technical Digest) discusses this in an article entitled, "Airplane upset recovery: A test pilot's point of view", p.18, elaborating on this caution.
This said, the next question is, what does the simulator do in such circumstances?
Obviously the sim doesn't just quit working so there is the consideration of degree of fidelity and not a question of fidelity itself. The data up to the approach-to-stall is assumed to be accurate.
It has been suggested that while the behaviour is not based upon post-entry-into-the-stall and actual stall data, there remains a certain level of useful replication by extension. The real question is, how much and how useful? The best advice from the AWST article is to train well to recognize and stay out of such extreme circumstances - good advice!, but we have had a number of full-stall accidents over the past seven years or so.
I am (was) a line pilot and am not a test pilot or an engineer so do not wish to tread in these areas without due care, but what seems required for recovery from a full stall in terms of pitch attitude and unstalling the wing from AoA's as seen here does not seem to differ wildly from technical expectations. Discussion?
Quote from JT:
Going with ‘the only game in town’ reasoning,
Being exposed to entry conditions and the resulting ‘maneuver’ simulation which took 20,000+ feet to negotiate and complete would be inspirational to me…..
It would inspire any pilot to diligently make whatever effort was necessary in the aircraft to avoid ever actually learning the level and extent of simulation fidelity involved.
Like PJ2, I hold the view that a bit of sim time for crew exposure to the improbable may (not necessarily will) provide some benefits.
Going with ‘the only game in town’ reasoning,
Being exposed to entry conditions and the resulting ‘maneuver’ simulation which took 20,000+ feet to negotiate and complete would be inspirational to me…..
It would inspire any pilot to diligently make whatever effort was necessary in the aircraft to avoid ever actually learning the level and extent of simulation fidelity involved.
Last edited by Jetdriver; 5th Apr 2012 at 02:49.
HN39;
Re, "I gather that AoA in your exercises did not exceed 40 deg enough to silence the stall warning, but did you by any chance observe a rapid drop in IAS between 25 and 40 deg AoA? "
I gathered from the session that it's difficult to simulate the loss of pitot/static information and get the exact same failures/ECAM messages and the method that got closest was failing ADRs and then re-instituting them to some degree. It didn't affect sim behaviour but it does affect available indications. This is a long way of explaining that I can't answer your question with any meaningful information. On one stall we had no warning which was because all ADRs were still failed and on others we had full FPV indications...a bit ad hoc in this area.
Re, "I gather that AoA in your exercises did not exceed 40 deg enough to silence the stall warning, but did you by any chance observe a rapid drop in IAS between 25 and 40 deg AoA? "
I gathered from the session that it's difficult to simulate the loss of pitot/static information and get the exact same failures/ECAM messages and the method that got closest was failing ADRs and then re-instituting them to some degree. It didn't affect sim behaviour but it does affect available indications. This is a long way of explaining that I can't answer your question with any meaningful information. On one stall we had no warning which was because all ADRs were still failed and on others we had full FPV indications...a bit ad hoc in this area.
CONfiture
I can't remember precisely but your 20000 feet figure would be my number too.
I was certainly impressed by the amplitude of negative pitch required to silent the stall warning. Not much blue sky left on the PFD. We, airline pilots, are simply not used to command such attitudes.
I can't remember precisely but your 20000 feet figure would be my number too.
I was certainly impressed by the amplitude of negative pitch required to silent the stall warning. Not much blue sky left on the PFD. We, airline pilots, are simply not used to command such attitudes.
PJ2
No kidding...not much blue left at all. And the AoA crept up - it didn't just change right away. The last bit from around 20deg to 10 seemed to go a bit faster.
No kidding...not much blue left at all. And the AoA crept up - it didn't just change right away. The last bit from around 20deg to 10 seemed to go a bit faster.
gums
@ PJ and 'nuts
Yeah the long response bothers/surprises me, too.
@ PJ and 'nuts
Yeah the long response bothers/surprises me, too.
I tried to explain, why that would be the case in my post 386 out of own expierience with stalls in fighter and trainer aircraft.
http://www.pprune.org/tech-log/46625...ml#post6769341
Thank´s all for the very good discussion points of the last few weeks, very open minded and not much noise.
I stumbled on a video from an F4 in an out of control situation ending in a flat spin, where the aerodynamic forces asociated with high AOA are visualized by contrails (all in the first minutes of the video).
Ejection Decision - A second Too Late! (1981) - YouTube
