AF 447 Thread No. 9
Originally Posted by Lyman
Clandestino has posited, in my opinion, that a shaker is not needed, simply because it is not fitted ...
Originally Posted by BEA
Airbus subsequently flew special flights to collect more accurate data at high angles
of attack and with an aircraft configuration close to that of the accident (mass, flight
level, Mach, etc.). These tests made it possible to refine the preliminary correlations
and to establish that the level of buffet was considered to be a deterrent by the test
pilots when the angle of attack was about 10°, corresponding to normal acceleration
amplitude of 1 g at the pilot’s seat. This angle of attack was reached at about 2 h 10
min 57 s during the accident flight.
of attack and with an aircraft configuration close to that of the accident (mass, flight
level, Mach, etc.). These tests made it possible to refine the preliminary correlations
and to establish that the level of buffet was considered to be a deterrent by the test
pilots when the angle of attack was about 10°, corresponding to normal acceleration
amplitude of 1 g at the pilot’s seat. This angle of attack was reached at about 2 h 10
min 57 s during the accident flight.
Originally Posted by rudderrudderrat
Why was something similar not thought to be necessary?
Originally Posted by gums
Good grief, Doze, how ya gonna get an overspeed warning if the air data system is FUBAR?
Originally Posted by gums
So maybe the junior crewmember up front was more worried about overspeed than stall or something else.
Originally Posted by Lyman
Whether or not the a/p was engaged, apparently, the selector was ON.
Originally Posted by Turbine D
very gentle adjustments of the sidestick are required?
Originally Posted by Turbine D
And finally, would the pilots who have or do regularly fly Airbus aircraft, such as Clandestino, be clamoring for sidestick shakers if it were of true benefit?
Originally Posted by slats11
The timing seems suspicious, and I would not be inclined to dismiss an electrical fault just because this fault should not have produced ozone. It might have produced something that the pilots believed was ozone.
Originally Posted by slat11
Yes the explanation could be an updraft of warmer air associated with Cb.
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I'm a bit late into the ozone discussion, but you're going to get my dimes worth anyway.
St. Elmo's fire and Ozone smell can be found from sea level and upwards when the conditions are right. On ships passing through tropical zones, St. Elmo's fire is often seen attaching itself to a yardarm of a mast, or even the outer corner of a bridge wing. The Ozone smell comes with the event.
Having had a lot to do with Ozone generators in a former life, I do know the smell of Ozone, and the linkage of St. Elmo's fire to that of the Ozone smell is also one I know well.
The PNF had crossed the ITCZ many times and was well aware of what he saw and smelled, and any conjecture that the smell was of electrical origin is just that - conjecture.
St. Elmo's fire and Ozone smell can be found from sea level and upwards when the conditions are right. On ships passing through tropical zones, St. Elmo's fire is often seen attaching itself to a yardarm of a mast, or even the outer corner of a bridge wing. The Ozone smell comes with the event.
Having had a lot to do with Ozone generators in a former life, I do know the smell of Ozone, and the linkage of St. Elmo's fire to that of the Ozone smell is also one I know well.
The PNF had crossed the ITCZ many times and was well aware of what he saw and smelled, and any conjecture that the smell was of electrical origin is just that - conjecture.
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@ Clandestino
Then why do all Boeings & L1011s etc. have stick shakers, despite having natural pre-stall buffets?
Belt & Braces perhaps?
Repeat after me: shakers are devices fitted to aeroplanes with natural pre-stall buffet too weak to comply with certifying regulations.
Belt & Braces perhaps?
Beats me. Where did you get the reference about Anyboeing and 1011 having natural pre-stall buffet? Now we know 330 has it and 1g amplitude at cockpit is not what anyone would call "light buzz".
Anyway, what would have happened to flight controls of the aeroplane with synthetic pitch feel that suddenly got fed with low speed signals in cruise?
Anyway, what would have happened to flight controls of the aeroplane with synthetic pitch feel that suddenly got fed with low speed signals in cruise?
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Where did you get the reference about Anyboeing and 1011 having natural pre-stall buffet?
Anyway, what would have happened to flight controls of the aeroplane with synthetic pitch feel that suddenly got fed with low speed signals in cruise?
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Buffet was not noted on CVR. Buffet was determined by analyzing accel. The aC did not pitch nose down at Stall.
The pilots were not privy to recorded data on flight recorders. The Shaker vibrates the stick with no net effect on Pitch. Most installs include a very loud and disconcerting clatter, there is virtually no chance to miss the warning, though of course a possibility exists that it will be ignored or misunderstood. Marvin Renslow proved an exception.
I think any agreement on these points may be impossible, except to agree to disagree.
End of shaker discussion pour moi.
The pilots were not privy to recorded data on flight recorders. The Shaker vibrates the stick with no net effect on Pitch. Most installs include a very loud and disconcerting clatter, there is virtually no chance to miss the warning, though of course a possibility exists that it will be ignored or misunderstood. Marvin Renslow proved an exception.
I think any agreement on these points may be impossible, except to agree to disagree.
End of shaker discussion pour moi.
Last edited by Lyman; 16th Jul 2012 at 23:12.
Training and "feel"
@ Cland..... my comment to Doze was a "barb" about the almost perfect flight control laws and reversion sequences, especially WRT to stall warning/avoidance. And with respect to energy required to overspeed at the limits of the envelope, I stand my ground. With even a "limit" of "x" gees above gee=one, kinetic energy is enough to do exactly what the dweeb did - pull and pull to the limits and run outta energy while transitting the stall protection limits, then get to new territory. pushing forward would have equally bad outcomes if the "overspeed" "protections" ( how I hate that term) are FUBAR due to invalid speed inputs to HAL.
Thanks, Wolf, for the IFR training comments. I followed the same procedure for many years when dual, and when in a chase plane for the single-seaters I watched and talked a lot on the inter-flight radio. In the Viper, we were in a back seat and the control stick did not move or reflect what Joebaggodunuts was doing up front. So watch the gauges and feel the jet, then take over if things are going to hell.
Back to Cland..... From the CVR fidelity ( could detect switch changes) and the comments by the troops, doesn't sound as if the AB330 has pronounced buffet in the stall regime. On the other hand, the older designs many of us flew from the 60's and on had distinct pre-stall indications. In my case, we had vastly larger margins from stall-onset to actual stall, as well as immensely larger speed margins before reaching VNe.
An example presented was to have a shaker or pusher when the jet had no clear pre-stall buffet or warning. So I flew the VooDoo, which fit the description when supersonic. But sub-sonic, the thing shook and wobbled and such that only a hamburger would have pulled harder. You could also feel "stick lightening" ( also feel it supersonic, but no buffet). I will bet a hundred bucks I could fly with you in a pre-AB330 heavy and show you the buffet or buzz indicating an approach to a stall.
I read the CVR again, and the experienced pilot is telling the other guy to stop climbing and to be "gentle". After a minute of fruitless talk, he calls for the aircraft commander. All the while the stall warning doofer is going off. I never wished to fly a "crewed jet", and what we saw in AF447 confirmed my fears. " I got it, no, you got it........" Least in the Viper we could completely cut out the student's stick very easily.
Thanks to JC for reviewing the CVR comments for first minute or so.
Thanks, Wolf, for the IFR training comments. I followed the same procedure for many years when dual, and when in a chase plane for the single-seaters I watched and talked a lot on the inter-flight radio. In the Viper, we were in a back seat and the control stick did not move or reflect what Joebaggodunuts was doing up front. So watch the gauges and feel the jet, then take over if things are going to hell.
Back to Cland..... From the CVR fidelity ( could detect switch changes) and the comments by the troops, doesn't sound as if the AB330 has pronounced buffet in the stall regime. On the other hand, the older designs many of us flew from the 60's and on had distinct pre-stall indications. In my case, we had vastly larger margins from stall-onset to actual stall, as well as immensely larger speed margins before reaching VNe.
An example presented was to have a shaker or pusher when the jet had no clear pre-stall buffet or warning. So I flew the VooDoo, which fit the description when supersonic. But sub-sonic, the thing shook and wobbled and such that only a hamburger would have pulled harder. You could also feel "stick lightening" ( also feel it supersonic, but no buffet). I will bet a hundred bucks I could fly with you in a pre-AB330 heavy and show you the buffet or buzz indicating an approach to a stall.
I read the CVR again, and the experienced pilot is telling the other guy to stop climbing and to be "gentle". After a minute of fruitless talk, he calls for the aircraft commander. All the while the stall warning doofer is going off. I never wished to fly a "crewed jet", and what we saw in AF447 confirmed my fears. " I got it, no, you got it........" Least in the Viper we could completely cut out the student's stick very easily.
Thanks to JC for reviewing the CVR comments for first minute or so.
And the abruptly increased temperature in the cockpit?
There are still some details that appear to be without explanation.
It is easy to overread or under read a CVR transcript. Human behavior psychologists believe that 10% of communication is the words themselves, 30% is the tone and the way the words are said, and up to 60% is nonverbal cues. I expect the exact words used account for > 10% when considering technical and procedural matters. On the other hand, we don't have a complete transcript (for understandable reasons) and so we may be missing some information which would help put things into context.
Why did the Captain not get a useful handover when he returned to the cockpit? Had things already degenerated that much. He got garbled bits if information plus lots of warnings and alarms plus a feeling that things were not right ( abnormal pitch attitude). It would have been perplexing to understand what had gone wrong in the brief interval since he had left the cockpit.
There are still some details that appear to be without explanation.
It is easy to overread or under read a CVR transcript. Human behavior psychologists believe that 10% of communication is the words themselves, 30% is the tone and the way the words are said, and up to 60% is nonverbal cues. I expect the exact words used account for > 10% when considering technical and procedural matters. On the other hand, we don't have a complete transcript (for understandable reasons) and so we may be missing some information which would help put things into context.
Why did the Captain not get a useful handover when he returned to the cockpit? Had things already degenerated that much. He got garbled bits if information plus lots of warnings and alarms plus a feeling that things were not right ( abnormal pitch attitude). It would have been perplexing to understand what had gone wrong in the brief interval since he had left the cockpit.
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@ Clandestino,
Quote:
Originally Posted by Turbine D
very gentle adjustments of the sidestick are required?
The reference you mentioned is the TAM incident. What I referred to in the BEA Final Report was in Appendix 6, Page 1.
Airbus "Unreliable Speed Indication" Procedure, A330 Air France FCOM:
Guess the TAM folks proved the Air France FCOM wrong?
Quote:
Originally Posted by Turbine D
And finally, would the pilots who have or do regularly fly Airbus aircraft, such as Clandestino, be clamoring for sidestick shakers if it were of true benefit?
I am sorry Sir, that I gave you credit for something that didn't deserve credit. I was just going by your previous information (Bio) that very recently changed including your location...
Quote:
Originally Posted by Turbine D
very gentle adjustments of the sidestick are required?
Originally posted by Clandestino: Bravo sierra perpetuated on PPRuNe. Read the report. Page 87. Slamming the stick from full back to full forward in ALT won't kill or even hurt you, if the average of pitch gyrations is centered on cruise pitch.
Airbus "Unreliable Speed Indication" Procedure, A330 Air France FCOM:
During this failure identification time, since the flight control laws may be affected, it is recommended to maneuver the aircraft with care until the ADR (s) is (are) switched off.
Quote:
Originally Posted by Turbine D
And finally, would the pilots who have or do regularly fly Airbus aircraft, such as Clandestino, be clamoring for sidestick shakers if it were of true benefit?
Originally posted by Clandestino: Who said I regularly fly Airbus? I was just a line jock, warming the RHS of 319/20 for a bit less than two years. Who gives a rat's stern about me? It is all in the certification standards!
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GPS and INS integration
dCLbydalpha
There is a lot of work in this area - and QANTAS and Honeywell are in the lead on it: See this ICAO document one of many - https://docs.google.com/viewer?url=h...%2F6104_en.pdf
The airworthiness authorities basically demand it. In reference to the example, how many combined GPS/Inertial sensors are certified by a civil air authority for navigation?
There is a lot of work in this area - and QANTAS and Honeywell are in the lead on it: See this ICAO document one of many - https://docs.google.com/viewer?url=h...%2F6104_en.pdf
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from BEA: "Control of the flight path does not correspond to what is expected. The amplitude of the actions may doubtless be explained by the highly charged emotional factors generated by the unexpected autopilot disconnection in the context of the flight."
Sounds a lot like some folks here.... Conclusion, doubtless correct, no need for explanation or analysis.. "Trust us, this is a government opinion."
Eliminated are ham handed tendencies persist, despite busts on sim, rote obedience to Stall Warn on TO, palsy, or bad curry from flight kitchen.
On the other hand, maybe it is a quote from one of Dozy's posts... There is a familiar ring to the rhetoric...
Sounds a lot like some folks here.... Conclusion, doubtless correct, no need for explanation or analysis.. "Trust us, this is a government opinion."
Eliminated are ham handed tendencies persist, despite busts on sim, rote obedience to Stall Warn on TO, palsy, or bad curry from flight kitchen.
On the other hand, maybe it is a quote from one of Dozy's posts... There is a familiar ring to the rhetoric...
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What possible significance is the temperature in the cockpit?
Why was there not a proper handover to the captain when he returned to the cockpit?
When he entered, he asked "What are you doing?" The PNF (in the LHS), the much more experienced of the two copilots, responded: "What's happening? I don't know...I don't know what's happening". The captain didn't even resume his place in the LHS where he could assume control, he got into the jump seat behind the console. Ten seconds later, six stall warnings sounded in the space of four seconds. No reaction from any of the three pilots. Seventeen seconds on, at FL250+, the PNF asks: "What do you think? What should we do?". The captain replies, "I don't know. It's going down". He's been on the flight deck a full minute, during which time neither of the two copilots has been able to explain what's been happening, yet he makes no effort to assume control.
In his book Erreurs de Pilotage 5, Otelli points out that STALL was verbally annunciated 75 times, taking up a total time of 54 seconds; the stall itself lasted 4 minutes and 24 seconds.
Why was there not a proper handover to the captain when he returned to the cockpit?
When he entered, he asked "What are you doing?" The PNF (in the LHS), the much more experienced of the two copilots, responded: "What's happening? I don't know...I don't know what's happening". The captain didn't even resume his place in the LHS where he could assume control, he got into the jump seat behind the console. Ten seconds later, six stall warnings sounded in the space of four seconds. No reaction from any of the three pilots. Seventeen seconds on, at FL250+, the PNF asks: "What do you think? What should we do?". The captain replies, "I don't know. It's going down". He's been on the flight deck a full minute, during which time neither of the two copilots has been able to explain what's been happening, yet he makes no effort to assume control.
In his book Erreurs de Pilotage 5, Otelli points out that STALL was verbally annunciated 75 times, taking up a total time of 54 seconds; the stall itself lasted 4 minutes and 24 seconds.
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Obviously it has no significance whatever, it is not covered in the "analysis".
On the other hand, evidence of absence is not absence of evidence.
"why should anyone give a rip?" is your question rhetorical, rock hound?
What are the odds the report is a fiction?
On the other hand, evidence of absence is not absence of evidence.
"why should anyone give a rip?" is your question rhetorical, rock hound?
What are the odds the report is a fiction?
Last edited by Lyman; 17th Jul 2012 at 02:14.
Rockhound, I have absolutely no idea what the significance of the cockpit temperature is. I am asking a question, not posing an explanation. Likewise I don't know what the PNF turned to maximum just before. He denied he had touched the A/C, so maybe the radar range (they were discussing a possible deviation to the left at the time).
All I am saying is that it may possibly be of significance. Out of the blue. In the middle of an 11 hour flight. Just one minute before other problems quickly unfold.
Obviously the PNF can't explain what he can't understand. But I would like to think he could have given the Captain a reasonably coherent account of the events that had transpired.
The Captain seemed very slow to act. Given he had only left the cockpit 11 minutes earlier, it is unlikely he had been asleep and was suffering from sleep inertia. So why?
Well in fairness, what was he expected to make of the following?
A quick explanation that the autopilot dropped out and they climbed and then entered a stall may have been sufficient to give the Captain the required situational awareness.
Although we don't have the audio, it is likely that PF and PNF were somewhat agitated (or more) when the Captain returned. Lack of clear handover. And then confusion, lack of assertiveness, and likely increased agitation.
All I am saying is that it may possibly be of significance. Out of the blue. In the middle of an 11 hour flight. Just one minute before other problems quickly unfold.
Obviously the PNF can't explain what he can't understand. But I would like to think he could have given the Captain a reasonably coherent account of the events that had transpired.
The Captain seemed very slow to act. Given he had only left the cockpit 11 minutes earlier, it is unlikely he had been asleep and was suffering from sleep inertia. So why?
Well in fairness, what was he expected to make of the following?
What’s happening? I don’t know I don’t know what’s happening
We’re losing control of the aeroplane there
We lost all control of the aeroplane we don’t understand anything we’ve tried everything
Although we don't have the audio, it is likely that PF and PNF were somewhat agitated (or more) when the Captain returned. Lack of clear handover. And then confusion, lack of assertiveness, and likely increased agitation.
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slats11;
That's the problem, they didn't know they were "stalled".
You're right though, a quick briefing by the PNF may have helped, but on the other-hand he probably thought the PF would do it.
A quick explanation that the autopilot dropped out and they climbed and then entered a stall may have been sufficient to give the Captain the required situational awareness.
You're right though, a quick briefing by the PNF may have helped, but on the other-hand he probably thought the PF would do it.
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They were pitched up 15 degrees at FL350 and when the stall warning went off they didn't know they were in a stall? Sorry I guess we have covered this many times before. Unbelievable.
Ok. You are correct. I really meant that a coherent explanation from the PNF ( who seemed to have the better SA) that the AP had dropped out and they had climbed together with the Captain noting the pitch up attitude followed by the stall warning ...... Surely this would have been enough to make sense.
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Nothing coherent (crew wise) happened in that cockpit from the A/P disconnect through to the end. It would seem that the BEA's Human Resources Group were not able to format a reasonable explanation for this behaviour either.
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Hi Rockhound,
It's a clue that you've just entered a region of much warmer air suddenly.
If the outside air temperature has risen faster than the hot air trim valves can respond, then you may have just entered the warm rising air of a big CB.
Best recheck the OAT for possible engine anti icing.
The two copilots were maxed out when the Captain returned to the flight deck. I don't understand why he didn't ask for the Altitude Alert deviation warning ("C chord") to be silenced so he could think straight. It was constantly filling in all the gaps between the other aural warnings until impact.
What possible significance is the temperature in the cockpit?
If the outside air temperature has risen faster than the hot air trim valves can respond, then you may have just entered the warm rising air of a big CB.
Best recheck the OAT for possible engine anti icing.
The two copilots were maxed out when the Captain returned to the flight deck. I don't understand why he didn't ask for the Altitude Alert deviation warning ("C chord") to be silenced so he could think straight. It was constantly filling in all the gaps between the other aural warnings until impact.
