AIr France Passenger Jet drops off Radar
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Yea but he still had toga power and ten degrees nose up at low altitudes. If power + attitude = performance is supposed to solve all then that combo should have worked at the low altitudes, but didn't due to deep stall . Than HAS to be fixed first .
ejectx3
As HF3000 said: Power + Attitude = Performance (Always)
It may not equal the performance you were expecting though once stalled i.e. uncontrolled flight, as demonstrated in the BEA report where:
TOGA + ≥10° pitch = Very large sink rate.
Once stalled, (not a deep stall) stall recovery requires:
TOGA or Reduced thrust if pitch authority compromised by TOGA + about -2 to -3° pitch = ↑ IAS.
Once stall is broken:
TOGA + about +5 to +10° pitch (dependant on Alt & weight) = ↑IAS & ↑ALT
As HF3000 said: Power + Attitude = Performance (Always)
It may not equal the performance you were expecting though once stalled i.e. uncontrolled flight, as demonstrated in the BEA report where:
TOGA + ≥10° pitch = Very large sink rate.
Once stalled, (not a deep stall) stall recovery requires:
TOGA or Reduced thrust if pitch authority compromised by TOGA + about -2 to -3° pitch = ↑ IAS.
Once stall is broken:
TOGA + about +5 to +10° pitch (dependant on Alt & weight) = ↑IAS & ↑ALT
ejectx3
No you have missed the point. There is two types of flight, controlled and uncontrolled. You should always know which one you are in. In the AF447 crash the crew clearly didn’t. If they did they wouldn’t have stalled the aircraft.
No you have missed the point. There is two types of flight, controlled and uncontrolled. You should always know which one you are in. In the AF447 crash the crew clearly didn’t. If they did they wouldn’t have stalled the aircraft.
ejectx has not missed the point. Power plus Attitude does not work when stalled, especially with an AoA of 40°. +2° to -3° would not have saved them. Full forward stick, full nose down trim (stuck at 13° NU) and perhaps a boot of rudder to drop the nose may have saved them.
The idea of setting 10° and full power probably sounded good to those poor souls in the front of that "unstallable" aeroplane, their hands tied behind their back by everybody who was not in that cockpit.
The idea of setting 10° and full power probably sounded good to those poor souls in the front of that "unstallable" aeroplane, their hands tied behind their back by everybody who was not in that cockpit.
ejectx has not missed the point. Power plus Attitude does not work when stalled, especially with an AoA of 40°. +2° to -3° would not have saved them. Full forward stick, full nose down trim (stuck at 13° NU) and perhaps a boot of rudder to drop the nose may have saved them.
Capn Bloggs & ejectx3
I think you both need to re-read what I wrote, in particular:
You and ejectx3 have completely missed the point I and others having been trying to make. At the onset of the ADR failures if the pilots had simply maintained their current attitude & power they would be alive today. Power + Attitude = Performance would have saved them but having botched that very basic part of airmanship, they then botched the stall recovery, and yes airbus’s can stall in alternate and direct flight control laws and like most aircraft have a standard stall recovery but no they continued to pull back on the stick, WTFF we will never know and ended up in a deep stall. From this point it was all over rover.
I think you both need to re-read what I wrote, in particular:
Once stalled, (not a deep stall) stall recovery requires:
TOGA or Reduced thrust if pitch authority compromised by TOGA + about -2 to -3° pitch = ↑ IAS.
TOGA or Reduced thrust if pitch authority compromised by TOGA + about -2 to -3° pitch = ↑ IAS.
Last edited by 404 Titan; 7th Jul 2012 at 04:34.
AF447 was not in a deep stall. A deep stall is a characteristic of certain T tail designs which cannot be recovered from. It was sitting there, fat dumb and happy, with full back trim and not much counter elevator, waiting for someone to do something.
Actually, 404 titan, your stall recovery needs work: you should keep putting the nose down until you become unstalled, at least in the latest iteration of how to do it from Airbus. If you're at high altitude and well-stalled, that may be well down. It is highly likely that -2° to -3° isn't going to cut it, particularly if the underslung power is high.
By discussing the recovery from the stall, I have not "completely missed the point". Anybody can see that if the PF had simply held cruise pitch and reasonable power when the AP disconnected he wouldn't have pitched up. The fact that he didn't and got into a stall is the issue.
I put the word unstallable in quotes for a reason.
Come on! Have you read the report and what they were facing? Audio warnings coming and going, Flight Director bars going on and off/ commanding nose up and this little gem "Specifically, the approach to stall on a classic aeroplane is always associated with a more or less pronounced nose-up input. This is not the case on the A330 in alternate law. The specific consequence is that in this control law the aeroplane, placed in a configuration where the thrust is not sufficient to maintain speed on the flight path, would end up by stalling without any inputs on the sidestick."
Airmanship? There's no such thing. Training and experience equips pilots with the tools they need to cope with these situations. These guys were lacking in either or both, a situation that hopefully will now be addressed.
Actually, 404 titan, your stall recovery needs work: you should keep putting the nose down until you become unstalled, at least in the latest iteration of how to do it from Airbus. If you're at high altitude and well-stalled, that may be well down. It is highly likely that -2° to -3° isn't going to cut it, particularly if the underslung power is high.
By discussing the recovery from the stall, I have not "completely missed the point". Anybody can see that if the PF had simply held cruise pitch and reasonable power when the AP disconnected he wouldn't have pitched up. The fact that he didn't and got into a stall is the issue.
I put the word unstallable in quotes for a reason.
they then botched the stall recovery
Airmanship? There's no such thing. Training and experience equips pilots with the tools they need to cope with these situations. These guys were lacking in either or both, a situation that hopefully will now be addressed.
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All I'm saying is power + attitude will give a certain performance if you are unnstalled. If you are stalled it will not. First you must recover from the stall , then apply the above . So power + attitude will not always equal performance . A quite obvious and simple statement I thought.
Moderator
A deep stall is a characteristic of certain T tail designs which cannot be recovered from
You have the story with the commonly held misconception regarding T-tails. While the phenomenon has had more publicity in respect of some T-tail configuration aircraft, that is not the concern. Rather, the problem is that the aircraft (T-tail or whatever) gets into an angle of attack situation where the pitching moment characteristic (graph) changes and forward stick doesn't cause a nose down result. It may be necessary to adopt Type-specific inputs to break the stable situation. Indeed, it may not be possible to effect a satisfactory result with, inevitably, unsatisfactory subsequent results ...
I think that most of us would consider AF447's to have been in a fairly stable stalled situation (and, if forward stick were not able to force a nose down pitching motion .. a deep stall scenario) .. the aeroplane was quite happy to continue sitting just where it was, thank you very much.
Just a dreadfully tragic pity that none of the crew appeared to recognise the situation and, on a basis that "if one keeps doing what one was doing then one is likely to get the same result", .. try something different.
I suspect that the commander, some time after returning to the cockpit, probably realised what was what .. but had insufficient time left to him to do anything about it before being overtaken by events outside his control ..
you should keep putting the nose down until you become unstalled
Following on from the previous comment .. caveat - at excessive angle of attack the pitching moment characteristic can change undesirably and to the point where forward stick doesn't work as one might desire. If one finds oneself in the relevant angle of attack range things can get a little difficult.
Worth a read of some of the posts by Gums in the Tech Log threads where he describes this phenomenon in the early F16s. See, for instance, this post.
Reading Phil Oestricher's comments, one divines an uncanny similarity to AF447's situation, albeit that the F16 was heading down at around twice the ROD .. with the pilot having a nice option to deploy the anti-spin chute to force an alteration to the pitching moment characteristic.
A post by Machinbird, shortly after, adds further description.
Although I can't recall to attribute the reference, somewhere along the marathon threads in Tech Log a poster cited the following report which gives a bunch of information on post stall behaviour of interest to another Industry.
You have the story with the commonly held misconception regarding T-tails. While the phenomenon has had more publicity in respect of some T-tail configuration aircraft, that is not the concern. Rather, the problem is that the aircraft (T-tail or whatever) gets into an angle of attack situation where the pitching moment characteristic (graph) changes and forward stick doesn't cause a nose down result. It may be necessary to adopt Type-specific inputs to break the stable situation. Indeed, it may not be possible to effect a satisfactory result with, inevitably, unsatisfactory subsequent results ...
I think that most of us would consider AF447's to have been in a fairly stable stalled situation (and, if forward stick were not able to force a nose down pitching motion .. a deep stall scenario) .. the aeroplane was quite happy to continue sitting just where it was, thank you very much.
Just a dreadfully tragic pity that none of the crew appeared to recognise the situation and, on a basis that "if one keeps doing what one was doing then one is likely to get the same result", .. try something different.
I suspect that the commander, some time after returning to the cockpit, probably realised what was what .. but had insufficient time left to him to do anything about it before being overtaken by events outside his control ..
you should keep putting the nose down until you become unstalled
Following on from the previous comment .. caveat - at excessive angle of attack the pitching moment characteristic can change undesirably and to the point where forward stick doesn't work as one might desire. If one finds oneself in the relevant angle of attack range things can get a little difficult.
Worth a read of some of the posts by Gums in the Tech Log threads where he describes this phenomenon in the early F16s. See, for instance, this post.
Reading Phil Oestricher's comments, one divines an uncanny similarity to AF447's situation, albeit that the F16 was heading down at around twice the ROD .. with the pilot having a nice option to deploy the anti-spin chute to force an alteration to the pitching moment characteristic.
A post by Machinbird, shortly after, adds further description.
Although I can't recall to attribute the reference, somewhere along the marathon threads in Tech Log a poster cited the following report which gives a bunch of information on post stall behaviour of interest to another Industry.
Capn Bloggs
I have actually read the report and I can understand the overwhelming situation the crew were in with conflicting stall warnings, intermitant positive speed trend arrows, master cautions etc but a properly trained and functioning crew should have been able to handle the abnormal situation. I have deliberately used the term “Deep Stall” to emphasise the difficulty in recovering from a stall in a jet that would’ve had 5T of fuel in the stab tank and a very aft CofG. Having looked at this very scenario in the sim twice now, I can assure you relaxing back pressure on the stick and maintaining about -2 to -3° (max about -5°) pitch will reduce the AoA sufficiently to unstall the wing if performed without delay. Leaving the recovery too long though required full forward stick and full forward trim resulting in a pitch attitude in excess of -20 to -30° and a height loss that if in real life would most likely result in the loss of the aircraft.
Regarding Airbus’s generic recovery which isn’t in the A330 QRH it states:
I have actually read the report and I can understand the overwhelming situation the crew were in with conflicting stall warnings, intermitant positive speed trend arrows, master cautions etc but a properly trained and functioning crew should have been able to handle the abnormal situation. I have deliberately used the term “Deep Stall” to emphasise the difficulty in recovering from a stall in a jet that would’ve had 5T of fuel in the stab tank and a very aft CofG. Having looked at this very scenario in the sim twice now, I can assure you relaxing back pressure on the stick and maintaining about -2 to -3° (max about -5°) pitch will reduce the AoA sufficiently to unstall the wing if performed without delay. Leaving the recovery too long though required full forward stick and full forward trim resulting in a pitch attitude in excess of -20 to -30° and a height loss that if in real life would most likely result in the loss of the aircraft.
Regarding Airbus’s generic recovery which isn’t in the A330 QRH it states:
Stall Recovery When Aircraft is stalled
FIRST: AoA MUST BE REDUCED
Note: Increasing thrust has an adverse effect on AoA reduction for Aircraft with engines below aircraft CG
SECOND: If speed needs to be recovered.
FIRST: AoA MUST BE REDUCED
- Release back pressure on stick or column
- Nose down pitch input may be needed
Note: Increasing thrust has an adverse effect on AoA reduction for Aircraft with engines below aircraft CG
SECOND: If speed needs to be recovered.
- When stall indications cease, increase thrust with care due to possible pitch
A330 QRH procedure:
STALL RECOVERY
• Nose Down Pitch Control → Apply
Note: In case of lack of pitch down authority, reducing thrust may be necessary.
• Bank → Wings Level
When out of the stall (No longer stall indications):
• Thrust → Increase smoothly as needed
STALL RECOVERY
• Nose Down Pitch Control → Apply
Note: In case of lack of pitch down authority, reducing thrust may be necessary.
• Bank → Wings Level
When out of the stall (No longer stall indications):
• Thrust → Increase smoothly as needed
One thing that does seem to me to be a little odd about this and some other accidents caused by the same control inputs is this, when I first learned to fly in a Tommatohawk, I practiced stall recovery which was the very standard way, even with a "tee" tail, the other thing that seems odd to me is, if you had tried something for several minutes (not sure how long the accident sequence took, but some length of time) that didnt work, it would appear to me that trying something else would seem appropriate. The training of the PF would be an interesting thing to look at, did he, infact, do things like recover from a stall in the likes of a Tommatohawk during his training??
you should keep putting the nose down until you become unstalled
Following on from the previous comment .. caveat - at excessive angle of attack the pitching moment characteristic can change undesirably and to the point where forward stick doesn't work as one might desire. If one finds oneself in the relevant angle of attack range things can get a little difficult.
Following on from the previous comment .. caveat - at excessive angle of attack the pitching moment characteristic can change undesirably and to the point where forward stick doesn't work as one might desire. If one finds oneself in the relevant angle of attack range things can get a little difficult.
There was no nose authority and idle thrust was required at 35 degrees to bring the nose down. This worked fine. As the aircraft unstalled and pitch healthier, power was increased and standard recovery initiated. The last option being rolling the wings to 70 degrees with idle thrust. I did this training 15 years ago in Ansett and have not seen it since.
Last edited by Gnadenburg; 8th Jul 2012 at 02:16.
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Yep bloggs aware of the principles of pitot tube heat. So back to the original question, we all can see from the report that improper recognition of stall led to control inputs that ensured the aircraft remained stalled and then began to autorotate. Thus I return to the original question not discussed in the report, how come you can go from M.082 to stall speed and not notice? the sensor and ADR computer readouts and EFIS display conditions, noted and notwithstanding? There were no significant total deviations in altitude even at high pitch (about 2000 ft) max, at norm cz the aircraft would bunt and give you quite an altitude gain, pretty hard to induce a high speed stall in a climb, so speed is the key and how come they got so slow?
Moderator
the aircraft went from 10 degrees pitch to 35 degrees pitch and 80kts
Doesn't anyone get trained to look at the ball these days ? What would prompt any airline pilot to allow the ball to get to 35 degrees ?
There was no nose authority and idle thrust was required at 35 degrees to bring the nose down
In addition to the generally understood tale about low slung engines with the thrust line providing a nose up pitching moment, there is another force of note at play in this situation.
A very powerful destabilising force at low speed, high nose attitude, and high thrust/power is associated with the airflow turning into the engine nacelle (or the propeller in a turboprop installation). This results in a strong vertical force which is trying to pitch the aircraft nose up (especially in piston to turboprop conversions where the prop is located well out ahead of the CG for static mass balance considerations).
Hence two problems conspiring to need a reduction in thrust to reduce the destabilising pitching moment and allow the pilot to get the nose down.
Doesn't anyone get trained to look at the ball these days ? What would prompt any airline pilot to allow the ball to get to 35 degrees ?
There was no nose authority and idle thrust was required at 35 degrees to bring the nose down
In addition to the generally understood tale about low slung engines with the thrust line providing a nose up pitching moment, there is another force of note at play in this situation.
A very powerful destabilising force at low speed, high nose attitude, and high thrust/power is associated with the airflow turning into the engine nacelle (or the propeller in a turboprop installation). This results in a strong vertical force which is trying to pitch the aircraft nose up (especially in piston to turboprop conversions where the prop is located well out ahead of the CG for static mass balance considerations).
Hence two problems conspiring to need a reduction in thrust to reduce the destabilising pitching moment and allow the pilot to get the nose down.
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Perhaps I should recast the proposition?
I find the report notably lacking in discussion on the issue of probe failure(s) and the ADR failures nor is there any real review or discussion concerning stall speeds at that configuration and oat and pressure. The FD was also doing some weird stuff and so were the crew trying to follow it. What do we know about the lift characteristics of the A330 wing with ice or in precipitation or how ice accretes on the airframe? If you can ice up a Mirage in all the wrong places in TS tops then you can ice up an A330.
Or is this another case of 'sudden upset' syndrome identified by Boeing and evidenced from a number of 737 accidents, where unusual attitude indications are met by disproportionate responses and hence loss of control.
Sadly it goes to show the wisdom of that often forgotten saying from wise old aviators about mother nature getting you by the scruff of the neck on a dark night so you had better know your sh1t.
I find the report notably lacking in discussion on the issue of probe failure(s) and the ADR failures nor is there any real review or discussion concerning stall speeds at that configuration and oat and pressure. The FD was also doing some weird stuff and so were the crew trying to follow it. What do we know about the lift characteristics of the A330 wing with ice or in precipitation or how ice accretes on the airframe? If you can ice up a Mirage in all the wrong places in TS tops then you can ice up an A330.
Or is this another case of 'sudden upset' syndrome identified by Boeing and evidenced from a number of 737 accidents, where unusual attitude indications are met by disproportionate responses and hence loss of control.
Sadly it goes to show the wisdom of that often forgotten saying from wise old aviators about mother nature getting you by the scruff of the neck on a dark night so you had better know your sh1t.
the aircraft went from 10 degrees pitch to 35 degrees pitch and 80kts
Doesn't anyone get trained to look at the ball these days ? What would prompt any airline pilot to allow the ball to get to 35 degrees ?
Doesn't anyone get trained to look at the ball these days ? What would prompt any airline pilot to allow the ball to get to 35 degrees ?
Some of it could be generational. There's no interest in aviation with many. How could somebody who flies Airbus come to a simulator session where there is an unreliable airspeed component, and pretty much do what has been the hot topic for some time? That is, AF pancaking into the sea in an unreliable airspeed scenario.
Last edited by Gnadenburg; 9th Jul 2012 at 01:04.
Gnadenburg
I wonder sometimes that MS Flight Sim is one of our biggest enemies. Every Tom Dick and Harry has had it on their computer and within a few hours is able to do all sorts of "wonderful" things from the comfort of their nice stable armchair in the warm lounge at home, safely out of harms way of any CB's etc.
This flying lark no longer holds any mystery, hell any old fool can do it, just look at those that are so "proficient" on MS Flight Sim. There's no need for experience on the flight deck any more and a MPL is really plenty of preparation for the big bad world of airline flying. The CEO's 12 year old has proved this as he/she has got this flying game sorted just through the use of Flight Sim.
Personally, I think the amount of continuation and recurrent training required for cadet airline pilots, is significantly greater then what airlines are willing to invest. And from what I've read about the MPL, it doesn't address this inherent problem either. Which is basically, no experience.
This flying lark no longer holds any mystery, hell any old fool can do it, just look at those that are so "proficient" on MS Flight Sim. There's no need for experience on the flight deck any more and a MPL is really plenty of preparation for the big bad world of airline flying. The CEO's 12 year old has proved this as he/she has got this flying game sorted just through the use of Flight Sim.
Last edited by 27/09; 9th Jul 2012 at 10:24.
Had discussion with a cadet about his response to an UA situation when we were sitting at 35000'. The answer "TOGA 15degrees" sums it all up. We are not training pilots but cockpit monitors. It's the way the airlines like it as they can justify the reduction in pay. The tombstone imperative is still the only way safety is improved despite all the SMS buzzwords.