AF447 wreckage found
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These weren't the first airline crews to go all the way to the ground with the stick back. I just gave two briefings on Loss-of-Control Accidents and it seems to be a common theme.
I've also been researching cascading failures and multiple apparently random annunciations. We may have a bigger problem than it appears at first glance.
Goldfish
I've also been researching cascading failures and multiple apparently random annunciations. We may have a bigger problem than it appears at first glance.
Goldfish
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Hi,
TheShadow
Interesting .. but I read
The aircraft (announced by one of the pilot) go in alternate law and it's big difference when compare with direct law.
TheShadow
Interesting .. but I read
and the handling pilot now had an instant unalerted surprise handful of an aircraft in Direct Law with nearly full nose-up trim and near to full power
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Hence it recommends 5 degrees with CLB power. Totally wrong thing to do
If you are at 39000 and loose the airspeed indication all of sudden but still level, no change of airframe noise and altitude then you go for the table without setting 5° and CLB, therefore I cannot agree with you when you say that there is no airbus checklist for unreliable speed at cruise level, there is, and to me it's quite clear.
Thank you, TheShadow, very informative. I guess I come from a generation when "having to manually hand-fly an aircraft" was the preferred option.
If there's to be any real progress, I guess we need to examine what training led to the 'human factors' error they made. From my humble flight safety background, it usually turns out to be human factors rather than pilot error.
Next time I fly the pond, I'm tempted to fly it myself in a puddlejumper(again).
p.s. there will only ever be one 'procedure' for everything; it's called "airmanship".
If there's to be any real progress, I guess we need to examine what training led to the 'human factors' error they made. From my humble flight safety background, it usually turns out to be human factors rather than pilot error.
Next time I fly the pond, I'm tempted to fly it myself in a puddlejumper(again).
p.s. there will only ever be one 'procedure' for everything; it's called "airmanship".
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Stabilizer trim to 13 degrees up?
Sorry if this has already been brought up, but why would THS go from 3 to 13 degrees during the interval 2:10:51 (red ball 5) and the next entry 50 seconds later, and stay there for the next 4 minutes until the data stops?
The way I read it is that the AP had disconnected by this time, so was some other system automatially increasing THS in the 2:10:51 interval?
The way I read it is that the AP had disconnected by this time, so was some other system automatially increasing THS in the 2:10:51 interval?
Last edited by thcrozier; 28th May 2011 at 00:03. Reason: Clarification.
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But here's a clue. In the subsequent descent with static pressure increasing and the pitots still blocked?, even though the airplane was actually stalled (complete with stick-shaker) the indicated airspeed would be increasing alarmingly - courtesy of increasing static pressure. That's my guess - and it's anyways a physical fact, Been there and done that trick with frozen trapped water in the static lines (i.e. the opposite effect of trapped dynamic pitot pressure). There's also a report on the Irish Accident Board's site about a 747 on a test flight with uncapped static lines due maint error. It's an elucidating gaelic tale that shows just how confusing the pitot-static scenario can be. See below for how much a 1000feet of altitude change is worth in terms of additional "displayed knots". Ask any instrument technician. That's what I did. He'll demo it for you on his test-bench.
The second situation occurs when both the ram air inlet and drain hole become clogged, trapping the air pressure in the line. In level flight, the airspeed indicator typically remains at its present indication, but no longer indicates changes in airpseed. If the static port remains open, the indicator will react as an altimeter, showing an increase in airspeed when climbing, and a decrease in airspeed when descending. This is the opposite the normal way an airspeed indicator behaves, and can result in inappropriate control inputs because you will observe runaway airspeed as you climb, and extremely low airspeeds in a descent. This type of failure can be very hazardous because it is not at all obvious when it occurs
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Deep stall recovery
So it seems this plane was into a deep stall with nose up 16 degrees. Angle of attack 40 degrees. Vertical speed 110 knots. Horisontal speed low(60knots) Seems to me that the only option to get the plane out of this condition would be to get the nose of the plane into the direction of movment. Even full trottle would not be able to make a horisontal speed high enough to give a flyable angle of attack. So the only option would be to get the nose down in a steep dive.
I suggest using the rudders hard to one side to completely stall one wing get the plane to flip over in a spin would acctually help to get the nose down fast and then get the correct angle of attack back. An other option to get the plane to flip over would perhaps to give a high trust on only one of the engines - to create the nessesary rotation to loose all lift in one wing and get the nose.
I suggest even taking trottle to idle would not harm at all (once the spin is there - at suficcient altitude of course) - It might simplify recovery not have to deal with those nose-lifting forces and to rapid increasing speed diving with the nose to the ground. Simply get the nose of the plane into the direction of movementwould exchange height for flying speed rapidly and solve the problem. .
Also - I would like to know if comercical pilots ever practise stall recovery in a real plane in real air. I have practiced stall/spinn from 3000 feet in a sail-plane several times - and suggest practice of this method in a sailplane could be valuable even to comercical pilots.
The initial stall-spinn does not involve high G-forces. The G-forces will be felt when at high flying speed with the nose to the ground will slowly lift the nose back to horisontal (and then add some trottle to keep a normaliced flight) In my sailplane typically 2-3 G.
I'm not talking about "what to do when you get the stall-shaker alarm" but - what to do when your allredy deep into a stall - but horisontal wings - and nose up.
I also realize that there may be some flaws to my argument here- Im not an expert in this area.
I suggest using the rudders hard to one side to completely stall one wing get the plane to flip over in a spin would acctually help to get the nose down fast and then get the correct angle of attack back. An other option to get the plane to flip over would perhaps to give a high trust on only one of the engines - to create the nessesary rotation to loose all lift in one wing and get the nose.
I suggest even taking trottle to idle would not harm at all (once the spin is there - at suficcient altitude of course) - It might simplify recovery not have to deal with those nose-lifting forces and to rapid increasing speed diving with the nose to the ground. Simply get the nose of the plane into the direction of movementwould exchange height for flying speed rapidly and solve the problem. .
Also - I would like to know if comercical pilots ever practise stall recovery in a real plane in real air. I have practiced stall/spinn from 3000 feet in a sail-plane several times - and suggest practice of this method in a sailplane could be valuable even to comercical pilots.
The initial stall-spinn does not involve high G-forces. The G-forces will be felt when at high flying speed with the nose to the ground will slowly lift the nose back to horisontal (and then add some trottle to keep a normaliced flight) In my sailplane typically 2-3 G.
I'm not talking about "what to do when you get the stall-shaker alarm" but - what to do when your allredy deep into a stall - but horisontal wings - and nose up.
I also realize that there may be some flaws to my argument here- Im not an expert in this area.
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Bottle of Water = Attitude Indicator
If the pilots did believed "all indicators are down" then they could have used a bottle of water to get a rough idea of horizon. It would give an instant sanity check on the pitch and bank.
If you think you are -45 deg but you look at the water level shows +45 then you are likely to change from pull stick try to push stick. When you do so and the water level instantly responds gradually returning to level. The pilot then has a feel for the spacial orientation of the a/c in the absence of a visual horizon out of the window.
The jostling of the airframe would move the water around however I believe it would be enough to approximate in the absence of any other indicators.
It really sounds like they had no instrumentation or at least did not trust the stall warnings. Otherwise they would follow the stalled checklist.
GPS gives the ground speed and direction. Again not ideal but better than nothing. Clearly the pilots were way out of the normal trained situation and flight envelope.
A few comments refer to "seat of the pants" flying. This has itself caused incidents when pilots don't look at the instruments and instead rely on gut feel. The mind plays nasty tricks when you experience acceleration without visual reference points.
If you think you are -45 deg but you look at the water level shows +45 then you are likely to change from pull stick try to push stick. When you do so and the water level instantly responds gradually returning to level. The pilot then has a feel for the spacial orientation of the a/c in the absence of a visual horizon out of the window.
The jostling of the airframe would move the water around however I believe it would be enough to approximate in the absence of any other indicators.
It really sounds like they had no instrumentation or at least did not trust the stall warnings. Otherwise they would follow the stalled checklist.
GPS gives the ground speed and direction. Again not ideal but better than nothing. Clearly the pilots were way out of the normal trained situation and flight envelope.
A few comments refer to "seat of the pants" flying. This has itself caused incidents when pilots don't look at the instruments and instead rely on gut feel. The mind plays nasty tricks when you experience acceleration without visual reference points.
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Speevy,
If you get unreliable airspeed in the cruise suddenly with smooth flying conditions and everything normal then 5 degrees climb power may not kill you straight away. However, in a realistic scenario, with moderate turbulence, by the time you realise the aircraft has unreliable airspeed it's going to be possibly over 20 seconds from when it occurred. As a result your airspeed may already be far too high/low. By then pitching UP to 5 degrees (it will be a pitch up as you don't have 5 degrees pitch in the cruise normally) you are potentially worsening the situation. A slight overspeed is better than a low speed. Yet again, there is no procedure from Airbus for this situation. Your point of 5 degrees CLB was not designed for this scenario, let alone the fact that if your at your ceiling this is potentially disastrous.
If you get unreliable airspeed in the cruise suddenly with smooth flying conditions and everything normal then 5 degrees climb power may not kill you straight away. However, in a realistic scenario, with moderate turbulence, by the time you realise the aircraft has unreliable airspeed it's going to be possibly over 20 seconds from when it occurred. As a result your airspeed may already be far too high/low. By then pitching UP to 5 degrees (it will be a pitch up as you don't have 5 degrees pitch in the cruise normally) you are potentially worsening the situation. A slight overspeed is better than a low speed. Yet again, there is no procedure from Airbus for this situation. Your point of 5 degrees CLB was not designed for this scenario, let alone the fact that if your at your ceiling this is potentially disastrous.
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stall warning stops when you are in a stall
Contrary to what is mainly reported, it seems that the pilot recognized a stall but changed his mind because the stall warning stops when in a stall :
"From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. "
=> One can understand : the PF is the cause of the stall.
"The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied "
=> The pilot recognized a stall.
"At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs."
=> The PF is responsible for a new stall
"the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped. "
=> when the captain re-entered, no information was available to him
"the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again."
=> the stall warning sounded when he pitch-down then his reaction is to come back to the last situation when the stall warning didn't sounded i.e. with the nose up.
It is just a human reaction and the captain had no clue to help him.
QUESTION : since the stall warning stops when you are in a stall ( speed < 60 kt) but sounds when you are recovering, what has to be changed ?
"From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. "
=> One can understand : the PF is the cause of the stall.
"The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied "
=> The pilot recognized a stall.
"At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs."
=> The PF is responsible for a new stall
"the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped. "
=> when the captain re-entered, no information was available to him
"the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again."
=> the stall warning sounded when he pitch-down then his reaction is to come back to the last situation when the stall warning didn't sounded i.e. with the nose up.
It is just a human reaction and the captain had no clue to help him.
QUESTION : since the stall warning stops when you are in a stall ( speed < 60 kt) but sounds when you are recovering, what has to be changed ?
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Idiots (and pilots) summary of WTHIH?
Hamrah post #530 , wiggy post # 569, think your two posts are a good summary of the unfortunate situation the crew were handed by their aircraft.
I am, quite unashamedly, anti Airbus FBW.
22 years on a 737 perhaps labels me somewhat Jurassic, but the same scenario (more or less) on my prof check 48hrs ago (my instructor was psychic? ) was difficult but eminently doable.
Not entirely sure if the wonders of Airbus (uncrashable! ! as I cringe yet again remembering Bernard "cablecar "Z emphasising on the Beebs coverage of Farnborough airshow all those years ago) actually help or diminish the human ability to alleviate sh1t happening, my personal opinion is very much the latter.
Edited to say The Shadow post #590, I think you deserve "post of the thread award" & I wish I had the influence/contacts to secure you a secondment to the BEA for a few months.
I sincerely hope they have, and are allowed to utilise, as much imagination/lateral thinking/insight, as you have shown.
Illuminating post
2nd edit jcjeant post #598, interesting link. If indeed BUSS was a good thing, yet again, like AF skimping costs by not installing GPWS and the resulting A320 crash in Strasbourg, the bean counters should be ahead of the pilots, when we attribute blame.
Oh BTW, only very slightly off topic, have all you (fellow ) Boeing drivers read the recent bulletin re ice crystals ? ?
I am, quite unashamedly, anti Airbus FBW.
22 years on a 737 perhaps labels me somewhat Jurassic, but the same scenario (more or less) on my prof check 48hrs ago (my instructor was psychic? ) was difficult but eminently doable.
Not entirely sure if the wonders of Airbus (uncrashable! ! as I cringe yet again remembering Bernard "cablecar "Z emphasising on the Beebs coverage of Farnborough airshow all those years ago) actually help or diminish the human ability to alleviate sh1t happening, my personal opinion is very much the latter.
Edited to say The Shadow post #590, I think you deserve "post of the thread award" & I wish I had the influence/contacts to secure you a secondment to the BEA for a few months.
I sincerely hope they have, and are allowed to utilise, as much imagination/lateral thinking/insight, as you have shown.
Illuminating post
2nd edit jcjeant post #598, interesting link. If indeed BUSS was a good thing, yet again, like AF skimping costs by not installing GPWS and the resulting A320 crash in Strasbourg, the bean counters should be ahead of the pilots, when we attribute blame.
Oh BTW, only very slightly off topic, have all you (fellow ) Boeing drivers read the recent bulletin re ice crystals ? ?
Last edited by captplaystation; 28th May 2011 at 00:04.
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Satellite Uplink To Tech Support
Perhaps a big red button in the flight deck that instantly uplinks a live data feed from the flight computers to boffin headquaters at airbus would help. The boffins can analyse and have a chief test pilot tell you in real time what the heck is going on and the optimal recovery procedure. Meanwhile you can concentrate on flying. Low cost as you only get billed when you activate the uplink
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Why ??
My question is why did the crew fly through the storm in the first place. Other aircraft diverted up to 90 nm to go around the storm but not this crew. WHY ??
Was the radar working ? Did they leave Rio with inop radar? Did they simply ignore the radar?
It seems quite stupid to me to fly a passenger jet at hight altitude close to the coffin corner through a CB. What were they thinking? Had they diverted, they would be alive today.
Was the radar working ? Did they leave Rio with inop radar? Did they simply ignore the radar?
It seems quite stupid to me to fly a passenger jet at hight altitude close to the coffin corner through a CB. What were they thinking? Had they diverted, they would be alive today.
The first step in solving a problem is the acquisition of the correct information.
From the reports so far it seems obvious that this crew were faced with a considerable amount of conflicting information and distractions.
It is all too easy to look at an accident and think how an earth did that crew allow themselves to get into that situation? They were doing the best they could with the resources that were available to them at the time.
From the reports so far it seems obvious that this crew were faced with a considerable amount of conflicting information and distractions.
It is all too easy to look at an accident and think how an earth did that crew allow themselves to get into that situation? They were doing the best they could with the resources that were available to them at the time.
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I think TheShadow has interpreted the available facts and portrayed an extremely plausible sequence of events. That scenario is horribly plausible. That it was erudite and technically accurate certainly add validity. As a current 330-200 pilot I can envisage just such a sequence and can now perhaps understand the confusion and fear that must have reigned. Bravo!
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In the subsequent descent with static pressure increasing and the pitots still blocked?, even though the airplane was actually stalled (complete with stick-shaker) the indicated airspeed would be increasing alarmingly - courtesy of increasing static pressure. --TheShadow Post 590
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The captain left the cabin 10 minutes before the encounter so must have looked at the radar 100 miles ahead and been happy with it. Sounds like the turbulence wasn't a factor according to the report but the handling of the erronious airspeeds and autopilot and autothrottle disconnect were. I have never flown an airplane that you pull back on the controls with stall warnings but my Airbus friends say you can and the computer won't let you stall. I guess that depends on whether it is in normal, alternate or manual law. I think that is why I refused to fly the Airbus. My 4 airliners and 70 other types said if you stall lower the nose and add power. Not one said pull back. That was our spin entry when I was teaching aerobatics.
All the airlines I flew at had charts for unreliable airspeed showing power and attitude for your weight and altitude which would have taken care of this situation. We also had very qualified pilots in both seats so all had basic hand flying skills which were tested before being hired.
Now a lot of airliners are offering 18,000 per yr for a 250 hr pilot because the airplanes are automatic and don't require pilot skills, according to the manufacturer. See where we are going? I know these guys had some experience when the captain left but how much actual hands on time?
We were paid for our experience.
All the airlines I flew at had charts for unreliable airspeed showing power and attitude for your weight and altitude which would have taken care of this situation. We also had very qualified pilots in both seats so all had basic hand flying skills which were tested before being hired.
Now a lot of airliners are offering 18,000 per yr for a 250 hr pilot because the airplanes are automatic and don't require pilot skills, according to the manufacturer. See where we are going? I know these guys had some experience when the captain left but how much actual hands on time?
We were paid for our experience.
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Ribbon
That ribbon outside cocpit window would do the job better than any digital instrument to indicate direction of air compared to the plane.
Also:
What would be the difference, if any -aerodynamically - between a "deep stall" and a "flat spin". Correct me if I'm wrong; but wings and stabilizers are completely stalled. You have little if any elevator authority. Increasing throttle will push the nose up increasing the AoA further. No ailron authority. I guess the difference is in the rotation.
So: How to get out of it?
Also:
What would be the difference, if any -aerodynamically - between a "deep stall" and a "flat spin". Correct me if I'm wrong; but wings and stabilizers are completely stalled. You have little if any elevator authority. Increasing throttle will push the nose up increasing the AoA further. No ailron authority. I guess the difference is in the rotation.
So: How to get out of it?
Last edited by Ask21; 28th May 2011 at 00:51.