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I really wasn't going to reply again but... like a tickle...
fullforward, people like me? I have a Master in aerospace engineering and am working on my PhD (in the area of aerodynamics). I don't appreciate being labeled 'people like you'. I probably know more than you about stalls. The fact is, and this is an indisputable FACT, the plane was fully functioning and the pilots crashed this plane into the ocean. Talking about auto-trim, psychological anomalies or design flaws are the conspiracy here, not me stating the obvious that the pilots didn't know how to fly the plane. Don't shoot the messenger. |
A good post shadow. Interesting in that on a few occasions in the little bus on a normal go around the a/c some times over pitches with the speed reducing below VLS Airbus then had to change some control protections to include a mod to the speed reversions. Having said that disconnecting the auto guidance & applying some fwd stick puts things back to normality. I have not had that problem with the big bus. However a pilot must realise that the automatics are not infalable just like pilots aren't either.
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I have a Master in aerospace engineering and am working on my PhD (in the area of aerodynamics). I probably know more than you about stalls. |
When the media, AF, the investigation and the courts start using those 2 words, i expect an apology ZBMAN. |
but, wafelbolletjes, with all respect, are you a pilot? |
Will the pilot be aware that he's in abnormal Law? (and the portents of that)" The answer might well be: "Probably not" (there's nothing to promote awareness of this being the case i.e. no aural annunciation - and thus we arrive at: what now needs to be done that's essential for recovery?) AH no??? The PF announces Alternate Law when he takes manual control of the aircraft. It is in one of the first lines in the BEA communication !!! |
Please, refrain from ad hominem attacks, and focus on arguments instead. It is relevant to the matter under discussion. Whilst having every respect for those having technical qualifications far superior than a mere mortal pilot, such as I, unless you have done or are doing the job as a pilot you really have little appreciation of what these pilots were faced with. There is too much condemnation going on here of the pilot's actions, especially when we don't know all the facts. |
To TheShadow:
Your analysis is based on wrong assumptions: Three questions: 1. "Will the pilot be aware that he's in abnormal Law? (and the portents of that)" The answer might well be: "Probably not" (there's nothing to promote awareness of this being the case i.e. no aural annunciation - and thus we arrive at: what now needs to be done that's essential for recovery?) 2. "Does the elevator alone have sufficient authority to unstall the wings at max power or at idle?" The answer is probably not, at least not while the superior trim authority of the THS at 13 degs n/up holds sway.... and particularly not whilst at TOGA power. 3. "Why doesn't the elevator have sufficient authority to unstall?" The whole design premise of the THS is to reduce trim drag and allow the elevator to become more of an active trim and less of a primary flight control. This ideation works well 99.99% of the time and it's used in all models of airliners to some degree. They need the capability of coping with large CofG ranges to accommodate loading, fuel burn-off and configuration changes. Some aircraft augment this capability with tail-located fuel trim-tanks. However this minimalistic elevator design feature in the A330 apparently won't "work" in the progression of events that AF447 underwent. The analysis of Flight Safty makes much more sense. |
He's talking about Abnormal law, not Alternate law. The relevant difference here being autotrim not working in Abnormal law. |
abovethesky, it wasn't an attack, merely a request for information! It is relevant to the matter under discussion. Whilst having every respect for those having technical qualifications far superior than a mere mortal pilot, such as I, unless you have done or are doing the job as a pilot you really have little appreciation of what these pilots were faced with. There is too much condemnation going on here of the pilot's actions, especially when we don't know all the facts. Nevertheless, it is a valid question why the PF didn't try to unstall by nose down, and this question is valid no matter who asks it. See also the link provided by Flight Safty. |
He obviously misspoke, because they were in Alternate law, not Abnormal law. |
I found this CNN report interesting
CNN.com International - Breaking, World, Business, Sports, Entertainment and Video News |
Nevertheless, it is a valid question why the PF didn't try to unstall by nose down, and this question is valid no matter who asks it. |
face down *** up thats the way planes like to ****!
It's also how you recover from a stall. |
Quote: He obviously misspoke, because they were in Alternate law, not Abnormal law. |
Gee and I thought this was the "Professional Pilots rumor network"
There is no "Abnormal" Law on the FBW Airbus. :ok: Normal Alternate 1 Alternate 2 Direct Ok. got it? Good Correction.........see below :ouch: |
Ok, Let me re-post the Quick Reference Handbook information on just what these guys faced. This info was available long before this accident. It may also help to explain to those that don't fly the Airbus.
The QRH spells the situation quite clearly:--- Unreliable speed indic/ADR check proc:- Maybe due to Radome damage, air probe failure or obstruction Indicated Alt may be effected if static probes effected Unreliable airspeed cannot be detected by the ADIRU Since Flight control laws maybe effected maneuver with care Unreliable speed may be suspected by- --- Speed discrepancies between ADR 1, 2, 3 and standby ---Fluctuating or unexpected increase/decrease/steady indicated speed or pressure altitude ---ABNORMAL CORRELATION OF THE BASIC FLIGHT PARAMETERS ---Abnormal AP/FD/ATHR behavior ---Stall warnings, or overspeed warning or flap relief warnings that contradicts with at least one of the indicated speeds -RELY ON THE STALL WARNING THAT COULD BE TRIGGERED IN ALTERNATE OR DIRECT LAW. IT IS NOT EFFECTED BY UNRELIABLE AIRSPEEDS BECAUSE IT IS BASED ON AOA -DEPENDING ON THE FAILURE, THE OVERSPEED WARNING MAY BE FALSE OR JUSTIFIED. BUFFET ASSOCIATED WITH THE OVERSPEED VFE WARNING IS A SYMPTOM OF A REAL OVERSPEED CONDITION. ---Inconsistencies between radio altitude and pressure altitude ---Reduction in aerodynamic noise with increasing airspeed or increase in aerodynamic noise with decreasing speed *my capitals to emphasize some sections* |
There is no "Abnormal" Law on the FBW Airbus. |
Above the sky....... Yes I must apologize you are correct. I just looked at FCOM 1 and it applies during abnormal attitudes.......
I'll take my foot out of my mouth now :E |
1. This crew got killed in their frantic struggle with an erroneous system. There are flaws in the system that prevented them from correctly recognizing the situation.
Air France Pilots Were Probably Confused by Cockpit Instruments in Crash - Bloomberg "The data and cockpit voice recording suggest the pilots never realized that the plane had stalled, BEA Chief Investigator Alain Bouillard said in an interview. “They hear the stall alarm but show no signs of having recognized it,” he said. “At no point is the word ‘stall’ ever mentioned.” 2. The PF did try to pitch down. The system acknowledged this effort with a renewed stall warning. He did probably not try again. Criminal neglect is to blame at this stage somebody who is not here anymore to explain his actions, instead of questioning the entire system including training. |
Let me bang on like a broken record about the very similar Air Caraibes A330-200 incidents (2 of them, handled successfully, the same way, in September of 2006):
http://www.eurocockpit.com/docs/ACA.pdf In the case detailed, the "incident" lasted about 2 minutes, from initial unreliable airspeed disconnect to restoration of working FDs and APs. During that time (and, to be fair, the way in which the a/c had been set up in the preceding few minutes to deal with icing and turbulence) the PF had time to: a) safely and successfully fly the plane using "manually" set thrust and pitch; b) consult the GPS Altitude and Groundspeed; c) listen to the PNF going through the Unreliable Airspeed checklist (with a plethora of Stall, Overspeed and other warnings sounding); d) decide that the Stall Warnings were inappropriate (and thus holding on to his thrust and pitch decisions); e) notice that the Checklist contained contradictory advice regarding stall warnings. So, what was different with AF447? Obviously, we do not know if the circumstances facing the crew were identical. And we do not know if they used the checklist. And we do not know if the checklist was identical. And we don't know why the crew took the decisions they did. But we do know that the Air Caraibes PF was quick enough to figure that almost nothing the a/c was telling him - airspeed, AoA, stalls, overspeeds, checklist advice - was going to help him keep his plane up. |
Gee and I thought this was the "Professional Pilots rumor network" There is no "Abnormal" Law on the FBW Airbus. http://images.ibsrv.net/ibsrv/res/sr...ies/thumbs.gif http://www.airbusdriver.net/airbus_fltlaws.htm: ABNORMAL ALTERNATE LAW Abnormal Alternate Law is activated if the airplane enters an unusual attitude, allowing recovery from the unusual attitude.
Maybe you could check the exact parameters for this? |
I found the CNN story posted above interesting too, I never knew that AF had RR engines on their A330s, nor that AF routinely fly their aircraft with gear down in cruise. :ugh:
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Quote from FCOM 1
Abnormal law due to: - Pitch attitude >50 deg nose up or 30 deg nose down - Bank angle >125 deg - AOA > 30 deg or < -10 deg - Speed > 440 kt or <-60 kt -Mach >.96 or < 0.1 The law in pitch is the Alt law without protections and without auto trim. In Roll it's full authority direct law with Alt Yaw After recovery they are:- Pitch Alt law Roll. direct law with yaw Alt law. :ok: |
I found the CNN story posted above interesting too, I never knew that AF had RR engines on their A330s, nor that AF routinely fly their aircraft with gear down in cruise |
Better Training
Let me bang on like a broken record about the very similar Air Caraibes A330-200 incidents (2 of them, handled successfully, the same way, in September of 2006): http://www.eurocockpit.com/docs/ACA.pdf In the case detailed, the "incident" lasted about 2 minutes, from initial unreliable airspeed disconnect to restoration of working FDs and APs. During that time (and, to be fair, the way in which the a/c had been set up in the preceding few minutes to deal with icing and turbulence) the PF had time to: a) safely and successfully fly the plane using "manually" set thrust and pitch; They did good. So maybe someone should learn something from the training they had. Although this forum is full of professional pilots saying that the AF crew were professional, people out there clearly expect a different standard. |
Don't think
"" The statistical data shows that, when confronted by a stall, in 80% of cases, pilots pull back the control column, in a sort of reflex movement, which continues the loss of control.
The aircraft was subjected to a series of four full and rapid rolls. The first was attributed to the force brought to bear by the pilot on the left part of the control column; the following ones were due to pilot overcompensation on the roll then the stall. Having pulled the control column fully back and thus caused maximum nose up pitch, the pilot rectified this by pushing the control column fully forward. The aircraft dipped, with its nose going under the horizon by 32°. The roll-off from +50 to –32° in seven seconds was remarkable." REPORT on the incident on 24 September 1994 during approach to Orly (94) to the Airb" WHEN YOU EAR A STALL WARNING = you are dead within a minute or two instead you nose down. It seems that 80% of the crew have not this picture in mind = there plane is a stone. The beginnig of the stall is the plane is rocketed to a high altitude then fall. That's all folks. This is the FIRST lesson of 100% of the instructors in the world. 80% of the crews don't follow their first lesson : it is this mental reaction that has to be fightened, not the plane. |
Just a thought, but assuming this was visible on the radar at the time the Captain left the flight deck, was this really a good time for him to take his in-flight rest period ?
Think I might have waited somehow ...... http://i52.tinypic.com/2927j8l.jpg |
Edmund......This is not new, before the Air Caraibis incident my Airline had a similar thing occur over the South China sea in an A330. They had their pitot probes ice up from super cooled water and they then had all the same things happen.
AP A/THR dropped out Simultaneous overspeed AND under speed warnings Alternate Law Etc etc They were initial hung out to dry but the union proved the Radar was at fault and the crew hadn't actually exceeded any limitations. So, the Airline changed the Radars on all the 330's and changed the Pitot tubes to the newer model. This is not a new thing.. |
For those not familiar with Airbus abnormal law:
An abnormal attitude law in pitch and roll is provided if the aircraft is in flight and in any of these conditions : – Pitch attitude > 50◦ nose up or 30◦ nose down – Bank angle > 125 ◦ – Angle of attack > 30◦ or < - 10◦ – Speed > 440 kt or < 60 kt – Mach > 0.96 or < 0.1 The law in pitch is the alternate law without protection (except load factor protection) and without auto trim. In roll it is a full authority direct law with yaw alternate. After recovery, the flight controls laws are: in pitch : alternate law in roll : direct law with yaw alternate law |
With other A330 similar incidents after exiting the area and the probes de-iced most Control Laws returned to normal. ( With one they had a Prim fault that they couldn't reset I think ). All flights landed normally with only a few injuries from the Turbulence ( WX ) encounter.
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CLUES?
The more I read, the more clear it gets: the poor guys failed to recognize they were flying a full stalled plane, got absolutely scared by the bells and whistles blaring all the time, rocking wings, winding down altimeters, a panicked captain shouting instructions and simply frozen at the controls (or even worse, giving inputs that agravated the situation), failing to do the only thing that would have saved the day.
Pure lack of proper training, basic airmanship & situation awareness. It's hard to admit that a lot of us could have reacted exactly the same way.:{ A perfectly flyable aircraft turned into a gigantic coffin. Of course there'll be endless theories about A330 systems, speculations on Boeing x Airbus, if this, if that etc... |
Has anyone considered the 5000kg's of fuel in the trim tank in cruise has an influence on the stall with regard to C of G?
Most of the times we practice stall recovery (in alternate law) in the sim, as per the new requirement, the stalling is done at a lower level than when aft trim fuel has taken place (FL255). I have not tried it with 5000kg in the trim tank at 38000ft yet. I reckon it is definitely not a pleasant outcome, however, we are all trained to avoid this and fly pitch angle and power setting. |
Severe stall recovery
OK- I'm not a professional pilot - but I did my first stall/spin recovery from 3000 feet at age 14 in an sailplane training and solo flying( a long time ago) - so thats my background.
One of the most interesting issues here is what options the captain had when he arrived in cocpit - assuming he recognized the stalled configuation. Assuming the AoA allready in the +40 degrees area and 10000 feet/min sink-rate. 13deg trim obviously led to the disaster - but at 40 deg AoA on wings - would not the horisontal stabilizeer/elevator allready be fully stalled incapable of producing a tail-lifting force at all. At some point of stall development pitch authority will be lost - isn't it so With a pitch +15 degrees - level wings . and Center of Gravity in the aft region - and since theres no stall recovery parachute installed - What are the options? Triming down the elevator is obvious - but it would increase the AoA of the horisontal stabilizor increasing the stall of that surface Exteding landing gears would be one option - to produce a nose-lowering force. I suggest also a mild reverse trust on engine might be one of very few options available. After all - what you would like to have is a pitch up stall converted to a steep - steep dive 70-80 degrees- where the forces of gravitation actually will work for you - not against you. In a steep dive with the nose directly towards the ground the Airplane will be flyable again. So the most realistic option would perhaps be to "drop a wing" - using rudder or aileron if aileron autority still exist - and then use rudder to convert a high bank angle to a steep vertical dive - thereby enabling oneself to fly again |
My first thoughts on reading the report were: why did the Captain leave the flight deck given the weather that must have been painted...even if he remained in the jump seat...as it was he returned to a chaotic cockpit, trying to play catch up on the preceding events. Also nobody has mentioned the well developed T-Cell that they descended into...even if they had reverted to basic power + attitude it would have been extremely difficult to hold an attitude in severe turbulence. And as far as I understand Direct Law still has roll-protection...making it even more difficult to keep wings level in severe turbulence. Plus it seems a greater diversion could have avoided taking them over the worst of it.... Strict Crew duty times and tight fuel margins may also be a factor here...
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Apologies if some of my terminology is wrong (I am merely a PAX!) However, it strikes me that this incident can be divided into two halves, before and after the return of the CPT.
First half, pitot tubes freeze giving unreliable air speed indications and AP disengages. PF continues to fly the plane for a short while but stalls. Pulls the nose up instead of pitching down. This could possibly have been prevented had he have know the attitude and ground speed prior to the failue of the Pitot tubes or followed some standard settings as per a previous post. Second half, CPT returns from his rest. Perhaps he had been in deep sleep and therefore not fully on the ball. He's met with a dark cockpit the plane oscillating and a whole load of alarms sounding. Firstly, he must have said someting (even WTF) yet there is no mention of this in the transcript. Question 1: Does he know the plane is in a stall or in a drive? You would have expected that the first things he would have checked are the airspeed, the altitude (dropping rapidly and appears to be displayed as shortlay afterwards the PF states that "we’re going to arrive at level one hundred") and the attitude (presumably still being displayed). At 2 h 12 min 02 both pilots were reporting no (valid) indications. Question 2: What does 'no' mean. Are they referring just to air speed? This strikes me as unlikely. Could the FDR say that the instruments were showing certain readings whereas in reality some instruments were out? However 40 seconds after the CPT arrives, the PF pushes forward on the stick, presumably in an attempt to dive and fly out of the stall (exactly the right thing to do). We know that the airspeed increased causing the stall alarm to resound. Question 3: What happens next? Does the PF pull back on the stick to get rid of the alarm (wrong thing to do)? Question 4: At 2 h 12 min 02 the thrust levers were are idle. Were they put there to reduce stresses on the plane in the dive / pull up recovery manoeuvre? Was this the right thing to do? At At 2 h 13 min 32 there are further inouts by each pilot. Question 5: What were theses inputs (push down or pull up)? Did they continue to attempt to recover from the stall or were they just sat there dumfounded with the nose pointing up? |
Quote from FCOM 1
"ALL PROTECTIONS ARE LOST IN DIRECT LAW" Other crews have been there and done that before and lived to tell the tail. The storms they inadvertently flew into contained severe turb and super cooled water drops too. |
if their are any A330 FO`s or captains here - have you tried stall recovery at FL350 or above?
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I'm glad wafelbolletjes has it right.
It must be so comforting to him. |
Speculations
The more I read, the more clear it gets: the poor guys failed to recognize they were flying a fully stalled plane, got absolutely scared by the bells and whistles blaring all the time, rocking wings, winding down altimeters, a panicked captain shouting instructions and simply frozen at the controls (or even worse, giving inputs that agravated the situation), failing to do the only thing that would have saved the day.
Pure lack of proper training, basic airmanship & situation awareness. It's hard to admit that a lot of us could have reacted exactly the same way...:{ A perfectly flyable aircraft turned into a gigantic coffin. Of course there'll be endless theories about A330 systems, speculations on Boeing x Airbus, if this, if that etc... |
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