AF447 wreckage found
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Flat Spin vs Deep Stall
Ask21:
A flat spin is a spin where the AOA is almost 90 degrees, so you are headed virtually straight down but with very little pitch.
Recovery is as follows:
Have all of the pax crowd into the front. Then have them all return to their seats as you level off with airspeed, if they can do it under the G's.
A deep stall can occur in some in some designs, generally T-tailed aircraft, and unlike a flat spin, the aircraft is steeply nose down. In this condition the wings block airflow over the tail, so you have no pitch or yaw control.
They say the chances of recovering from a deep stall are greater than from a flat spin, but I've never flown an aircraft with deep stall characteristics, so I don't know the recovery procedure for that one. I imagine it varies by aircraft.
A flat spin is a spin where the AOA is almost 90 degrees, so you are headed virtually straight down but with very little pitch.
Recovery is as follows:
Have all of the pax crowd into the front. Then have them all return to their seats as you level off with airspeed, if they can do it under the G's.
A deep stall can occur in some in some designs, generally T-tailed aircraft, and unlike a flat spin, the aircraft is steeply nose down. In this condition the wings block airflow over the tail, so you have no pitch or yaw control.
They say the chances of recovering from a deep stall are greater than from a flat spin, but I've never flown an aircraft with deep stall characteristics, so I don't know the recovery procedure for that one. I imagine it varies by aircraft.
Last edited by thcrozier; 28th May 2011 at 02:01. Reason: Information
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Hi,
Indeed .. high viscosity oil will made better .. but hey .. in emergency you take what at hand .....
I was in the crowd time ago .. in a Super Puma ...
10 people rushed forward on the pilot order .... some seconds after take off (bad loading cargo at the rear (was a ****load visible rear the net !)
Moving cargo during flight and no more prob !
That was in Libya ........
Bottle of Water!!!
You have all of the pax crowd into the front. Then have them all return to their seats as you recover, if they can do it under the G's.
10 people rushed forward on the pilot order .... some seconds after take off (bad loading cargo at the rear (was a ****load visible rear the net !)
Moving cargo during flight and no more prob !
That was in Libya ........
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White Knight.
Thanks for stating the bleeding obvious truth.
Keep saying it.
These 'button pushing' pilots are easily overwhelmed and if I do not watch it , I will soon join them in their fantasy button-pressing '**** all to fall back on' world.
The de-skilling of flying is NOT well intentioned!
The de-skilling of Flying is intended solely to cut costs, thus allowing airlines to make more money.
The PPL should advise pilots about basic stuff but many pilots, who have thousands of hours (doing sudoku & eating) can barely remember how to pilot an aircraft.
Time for a big-Time wake up call I think.
Perhaps not. Think of the cost!
Thanks for stating the bleeding obvious truth.
Keep saying it.
These 'button pushing' pilots are easily overwhelmed and if I do not watch it , I will soon join them in their fantasy button-pressing '**** all to fall back on' world.
The de-skilling of flying is NOT well intentioned!
The de-skilling of Flying is intended solely to cut costs, thus allowing airlines to make more money.
The PPL should advise pilots about basic stuff but many pilots, who have thousands of hours (doing sudoku & eating) can barely remember how to pilot an aircraft.
Time for a big-Time wake up call I think.
Perhaps not. Think of the cost!
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Hi,
Yes .. bean counters ...
To notice that the "BUSS" from AF statement not work well over level 250
Well ... the AF447 had about two minutes before reaching sea water when passing level 250
Methink it was maybe enough time to apply useful corrections .. if AC had a BUSS
Results may varies ....
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.
To notice that the "BUSS" from AF statement not work well over level 250
Well ... the AF447 had about two minutes before reaching sea water when passing level 250
Methink it was maybe enough time to apply useful corrections .. if AC had a BUSS
Results may varies ....
As a mere SLF this is all very interesting but I don't understand why, if faced with an altimeter winding down, the instinct isnt to put the nose of the a/c into the windstream. If control authority isn't there well unwind the THS ( as per Schipol, not) and if that doesn't work put it to idle, and if that doesn't work deploy the gear. Did these guys not know they were fighting for their lives ?
Last edited by Mr Optimistic; 28th May 2011 at 02:14. Reason: annoyance
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FBW and unreliable IAS
On the A330 FBW, with the IAS indicating excessively low speed, the pilot's correct action of pushing the nose down and pushing the thrust to max may, in my opinion, cause the auto trim to trim "backwards" causing a pitch up. In a normally indicating IAS, the pitch trim should trim forwards, but because of the false low speed indication, the forward application of the side stick will be interpreted by the FBW as a pitch forward and therefore countered with the pitch trim going backwards.
If I am not mistaken, a similar situation developed in a non-FBW A300 doing a botched-up go-around in Nagoya, Japan, many years ago. In that incident, the auto pilot interpreted the pitch forward command of the pilot through the control column as a situation that required the auto trim to trim backwards, causing the aircraft to stall, and eventually crash.
In FBW, with the auto pilot off, the pitch trim still acts on its own, as if the auto pilot is on (in a conventional aircraft). You must remember that there is no trim switch on the control column wheel on the A330 for the pilots to trim forwards or backwards as Normal and Alternate Laws do all the trimming for you. In fact, most FBW pilots will not notice the position of the pitch trim at any given moment, so it would not surprise me if the pilots on the ill fated AF447 had not noticed the extreme pitch up position the auto trim had placed the aircraft in... and so they would naturally react to the stall situation by pushing the side stick forward more, further aggravating the situation.
As I see it, with hindsight, the correct action to recover from the stall in this case would be to release the side stick, and manually roll the pitch trim forwards until it is out of the extreme pitch up position the aircraft was in.
If I am not mistaken, a similar situation developed in a non-FBW A300 doing a botched-up go-around in Nagoya, Japan, many years ago. In that incident, the auto pilot interpreted the pitch forward command of the pilot through the control column as a situation that required the auto trim to trim backwards, causing the aircraft to stall, and eventually crash.
In FBW, with the auto pilot off, the pitch trim still acts on its own, as if the auto pilot is on (in a conventional aircraft). You must remember that there is no trim switch on the control column wheel on the A330 for the pilots to trim forwards or backwards as Normal and Alternate Laws do all the trimming for you. In fact, most FBW pilots will not notice the position of the pitch trim at any given moment, so it would not surprise me if the pilots on the ill fated AF447 had not noticed the extreme pitch up position the auto trim had placed the aircraft in... and so they would naturally react to the stall situation by pushing the side stick forward more, further aggravating the situation.
As I see it, with hindsight, the correct action to recover from the stall in this case would be to release the side stick, and manually roll the pitch trim forwards until it is out of the extreme pitch up position the aircraft was in.
Last edited by Yipoyan; 28th May 2011 at 02:43.
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What Pish some folk post!
To fly an aircraft in IMC, one merely has to fly a certain attitude and a certain power.
Given that (probably) these guys had good attitude info, that only left them to sort out the power and fly.
The fact that they could not do 'straight and level' tells badly both about the computerised Airbus and the pilots easy reliance on its systems.
In rotten wx, autos often go for a wee lie down. Who then shall fly the aircraft?
Surely, the pilots?
In other words: Yet another 'loss of control' accident.
We need to get away from the automated flight regime that we are in today.
The writing is on the wall for all who care to read it and 228 people and their relatives know it.
Pilots must be able to fly.
And to a better standard than the autopilot!
To be brutally honest, a great many of my co-pilot colleagues could NOT manage their flying day without the autopilot. They would be sorely taxed.
These same co-pilots are now being promoted, having accrued about 2000 hrs.
To be even more brutally honest, I'll soon join them in their inadaquacy unless I make more of an effort to fly. (I have 10,000 hrs on regional ops)
It wil cost a lot of money to retrain these 'button pushers' to fly again, but they did it before (briefly) on their IR!
How much did recovering AF447 cost?
just an edit to say, there but for the Grace of God.......
To fly an aircraft in IMC, one merely has to fly a certain attitude and a certain power.
Given that (probably) these guys had good attitude info, that only left them to sort out the power and fly.
The fact that they could not do 'straight and level' tells badly both about the computerised Airbus and the pilots easy reliance on its systems.
In rotten wx, autos often go for a wee lie down. Who then shall fly the aircraft?
Surely, the pilots?
In other words: Yet another 'loss of control' accident.
We need to get away from the automated flight regime that we are in today.
The writing is on the wall for all who care to read it and 228 people and their relatives know it.
Pilots must be able to fly.
And to a better standard than the autopilot!
To be brutally honest, a great many of my co-pilot colleagues could NOT manage their flying day without the autopilot. They would be sorely taxed.
These same co-pilots are now being promoted, having accrued about 2000 hrs.
To be even more brutally honest, I'll soon join them in their inadaquacy unless I make more of an effort to fly. (I have 10,000 hrs on regional ops)
It wil cost a lot of money to retrain these 'button pushers' to fly again, but they did it before (briefly) on their IR!
How much did recovering AF447 cost?
just an edit to say, there but for the Grace of God.......
Last edited by BarbiesBoyfriend; 28th May 2011 at 02:47.
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The Captain's Response
I am definitely SLF.
The Captain re-entered the flightdeck in the middle of the developing situation. He had to gain situational awareness. He either gained it from the other pilots, in which case there would be a recording of what they thought was happening to the aircraft, or he gained it from his own senses i.e. whatever the instruments were then saying and what he could hear and feel.
It is fairly easy to assume the other pilots misinterpreting the information available to them and having formed an incorrect interpretation, continuing to apply the erroneous interpretion, disregarding evidence that conflicted with it. Unless the newcomer gained his understanding of the position by receiving an incorrect briefing, it is more difficult to accept that the Captain joined his fellow pilots' erroneous view of the situation without there being some pretty compelling, but ultimately wrong, data as to what the aircraft was doing.
The Captain re-entered the flightdeck in the middle of the developing situation. He had to gain situational awareness. He either gained it from the other pilots, in which case there would be a recording of what they thought was happening to the aircraft, or he gained it from his own senses i.e. whatever the instruments were then saying and what he could hear and feel.
It is fairly easy to assume the other pilots misinterpreting the information available to them and having formed an incorrect interpretation, continuing to apply the erroneous interpretion, disregarding evidence that conflicted with it. Unless the newcomer gained his understanding of the position by receiving an incorrect briefing, it is more difficult to accept that the Captain joined his fellow pilots' erroneous view of the situation without there being some pretty compelling, but ultimately wrong, data as to what the aircraft was doing.
The bare facts will show that they had 4 minutes plus to save the plane. Surely that should have been enough.
Last edited by Mr Optimistic; 28th May 2011 at 02:28. Reason: more annoyance
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As someone who has witnessed an A330 stall in the simulator I can assure you it is a 'pig' of an aircraft to recover if you get it fully developed. Also don't forget that you will only have the benefit of the BUSS if you have the presence of mind to switch off all the ADR's below FL250 in the middle of a very confusing situation and then it is as useless as a chocolate teapot if the aircraft is still in a stall. Sounds similar to the AIRNZ airbus in France, the aircraft should have been totally recoverable if the initial situation had been handled properly.
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SLF question here: Given the weather conditions at the time, is it possible they thought that they were caught in a violent sinking air column in the storm (ignoring the stall warning and paying more attention to erratic airspeed and the altimeter), and tried to power and climb their way out of it?
Of course something like that should be evident from the CVR, so I don't know what to think otherwise.
Of course something like that should be evident from the CVR, so I don't know what to think otherwise.
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Direct Law
As I see it, with hindsight, the correct action to recover from the stall in this case would be to release the side stick, and manually roll the pitch trim forwards until it is out of the extreme pitch up position the aircraft was in.
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We've had so many theories since the crash about what may have happened... from lightening to new composite materials on the plane delaminating in flight to a storm so bad that it broke the airplane apart.
In fact, it crashed just because the pilots couldn't fly the plane in a way that anyone with a PPL would know how to do (when stall warning occurs nose down full throttle!).
So basically the mystery of AF447 crash is that... the pilots crashed an aircraft that was in perfect working order. Yes, it was in perfect working order, failed pitot tubes doesn't mean the plane was not in PERFECT working order.
The pilots incompetentness are to blame for the death of all those poor helpless passengers.
In fact, it crashed just because the pilots couldn't fly the plane in a way that anyone with a PPL would know how to do (when stall warning occurs nose down full throttle!).
So basically the mystery of AF447 crash is that... the pilots crashed an aircraft that was in perfect working order. Yes, it was in perfect working order, failed pitot tubes doesn't mean the plane was not in PERFECT working order.
The pilots incompetentness are to blame for the death of all those poor helpless passengers.
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stall recovery
I'm a light airplane guy and don't know much about this, so forgive me if this is nonsense, but it strikes me that the A330 displayed remarkably good post-stall behavior -- no departure, no spin. It seems to have plowed along in a steep glide at 250 ktas or so (100 knots vertical speed, 20-25 degree flight path) and continued to respond to roll commands. But the advice to fly attitude confuses me. If you put the airplane symbol on the horizon, the airplane itself would still be stalled; it would be necessary to point it 20 degrees or so below the horizon to unstall it. It appears as if the sheer complexity of the systems masked the simplicity of what was really going on.
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thcrozier, you cannot select Direct Law just like that on the A330. Alternate Laws 1 & 2, and Direct Law are reversion modes... which means that they come in only after a higher law cannot be maintained (usually because of flight control computer(s) failures).
Theoretically in Normal Law, the FBW A330 cannot stall, but as we all know now, did so on AF447. Whether the aircraft reverted to Alternate Law or not I do not know, but even if it did (to help recover from the stall), pushing the side stick forward could very well have caused the pitch trim to go backwards because of the false low speed sensed (outside of the flight envelope), thus causing aggravation to the stall situation.
Theoretically in Normal Law, the FBW A330 cannot stall, but as we all know now, did so on AF447. Whether the aircraft reverted to Alternate Law or not I do not know, but even if it did (to help recover from the stall), pushing the side stick forward could very well have caused the pitch trim to go backwards because of the false low speed sensed (outside of the flight envelope), thus causing aggravation to the stall situation.