AF 447 Thread No. 11
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Re: F-GLZU
FWIW, the way I read he traces, and as I wrote earlier:
When airspeed is greater than Valpha-prot (*), lift at alpha-prot is greater than weight, Nz is greater than one, flight path gradient increases, pitch attitude increases for constant AoA,
The reverse applies when airspeed is less than Valpha-prot.
Agreed, there are minor pitch variations due to 'rough air' .However, I don't see that the trim speed matters. The elevator will accommodate any mistrim until it reaches its stop.
(*) Judging from the traces, Valpha-prot is around M.69 - M.70
When airspeed is greater than Valpha-prot (*), lift at alpha-prot is greater than weight, Nz is greater than one, flight path gradient increases, pitch attitude increases for constant AoA,
The reverse applies when airspeed is less than Valpha-prot.
Agreed, there are minor pitch variations due to 'rough air' .However, I don't see that the trim speed matters. The elevator will accommodate any mistrim until it reaches its stop.
(*) Judging from the traces, Valpha-prot is around M.69 - M.70
Last edited by HazelNuts39; 11th Nov 2013 at 08:59. Reason: asterix added
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Originally Posted by Dozy
@CONF - I've invited you on several occasions to start your own Habsheim thread in AH&N (the logical place to have it, as the incident is over two decades old) - but you have not as yet done so.
Nice ... but not really the kind involved in Habsheim ...
@Chris - I think we do know that Alpha Floor was not a consideration for the pilot of AF296, as he *disabled* A/THR (and thus A. Floor) by holding down the disconnect switches to perform the flypast.
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@vilas
Could you post a link to that MOI please? I don't think I have ever met the term before.
@Confiture
Quote?
Final Report of the Commission d'Enquete on the accident: Section 1.11.3
Could you post a link to that MOI please? I don't think I have ever met the term before.
@Confiture
Quote?
Final Report of the Commission d'Enquete on the accident: Section 1.11.3
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Originally Posted by OG
Final Report of the Commission d'Enquete on the accident: Section 1.11.3
Now where is the quote that Alpha-Floor was effectively inhibited ... ?
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@Confiture
Ten lines later it says that the A/THR was disconnected immediately after take off and twenty one lines later it records that between 50 and 40 ft AGL the CdB confirmed that the A/THR was disengaged.
As I understand it, alpha floor is an A/THR dependent function.
So you accept that he meant to make the demonstration without alpha floor and the record shows that he took action to inhibit alpha floor - why didn't he fly the demonstration in a manner consistent with his intent and earlier actions?
Ten lines later it says that the A/THR was disconnected immediately after take off and twenty one lines later it records that between 50 and 40 ft AGL the CdB confirmed that the A/THR was disengaged.
As I understand it, alpha floor is an A/THR dependent function.
So you accept that he meant to make the demonstration without alpha floor and the record shows that he took action to inhibit alpha floor - why didn't he fly the demonstration in a manner consistent with his intent and earlier actions?
Last edited by Owain Glyndwr; 11th Nov 2013 at 21:15.
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Originally Posted by OG
Ten lines later it says that the A/THR was disconnected immediately after take off
and twenty one lines later it records that between 50 and 40 ft AGL the CdB confirmed that the A/THR was disengaged.
As I understand it, alpha floor is an A/THR dependent function.
So you accept that he meant to make the demonstration without alpha floor and the record shows that he took action to inhibit alpha floor
why didn't he fly the demonstration in a manner consistent with his intent and earlier actions?
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@Confiture
OK, but for my information what would these additional steps have been?
Following on from that, would these steps have been known to the pilot? If they were then why did he not apply them if his intent was to make the demonstration with Alpha -Floor inhibited? If he was unaware that he should take these extra measures then he made the flight believing that he had inhibited it. In which case my question:
remains valid.
At 118 kts????
Yes, but Alpha-floor could trigger whatever the status of the A/THR ... unless one of the steps to prevent Alpha-Floor to trigger has been applied. It appears that none of these steps were applied.
Following on from that, would these steps have been known to the pilot? If they were then why did he not apply them if his intent was to make the demonstration with Alpha -Floor inhibited? If he was unaware that he should take these extra measures then he made the flight believing that he had inhibited it. In which case my question:
- why didn't he fly the demonstration in a manner consistent with his intent and earlier actions?
too fast
Quote from gums:
Later jets had an auto throttle system ( Hornet), and I am not sure of the implementation. Most Nasal radiators and some of us in the SLUF and Viper flew AoA on approach and cross checked the speed to make sure we had the correct configuration.
"Nasal radiators"? LOL!
So the A-7 Corsair was nicknamed SLUF? We have a civil a/c - very much not FBW - that used to be called FLUF, until they really stretched it and put weird bananas on the wingtips. (Also referred to as the "crab")
OG,
Something about "....where angels fear to tread"...?
Later jets had an auto throttle system ( Hornet), and I am not sure of the implementation. Most Nasal radiators and some of us in the SLUF and Viper flew AoA on approach and cross checked the speed to make sure we had the correct configuration.
"Nasal radiators"? LOL!
So the A-7 Corsair was nicknamed SLUF? We have a civil a/c - very much not FBW - that used to be called FLUF, until they really stretched it and put weird bananas on the wingtips. (Also referred to as the "crab")
OG,
Something about "....where angels fear to tread"...?
Last edited by Chris Scott; 12th Nov 2013 at 10:23.
Possible changes in FBW protections after A340 AIRPROX
Quote from vilas:
The change to AOA protection mode disengagement was done through MOI in 2005. With this software change AOA protection is no longer active when alpha is less than alpha prot and side stick has not been deflected since the last autopilot disconnection.
Quote from my response:
Have you quoted the MOI in 2005 verbatim? If so, in an identical repeat of the A340 AIRPROX of 2001, it would have prevented the engagement of AoA mode (referred to by the AAIB as AoA protection Law). Taken literally, that would represent a radical inhibition of engagement, not an additional means of disengagement.
If, on the other hand, "is no longer active" actually means "will disengage", it would be an additional means (condition, or criterion) for disengagement. But it would not apply if either sidestick had been moved during a period of hand flying. That would seem odd, but perhaps I'm overlooking something.
Reply from vilas:
...I have quoted the MOI verbatim.
Thanks, vilas. Like OwainG, I am not familiar with (or have forgotten!) the term "MOI", but I presume it's a publication for informing operators of technical mods?
In my response, I overlooked a second possible inference that might be made from the MOI. I refer to this mid-sentence phrase:
"...AOA protection is no longer active when alpha is less than alpha prot ..."
Does it mean that, by 2005 (about 4 years after the A340 AIRPROX), AI had discontinued the phase-advanced engagement of AoA mode ("AoA protection Law") cited in the AAIB Bulletin of 2001? Page 11:
"Ten seconds after the autopilot disengaged, the corrected or phase-advanced angle of attack (a computed parameter which is is not recorded but can be calculated by [AI] from the DFDR data) reached the 'alpha prot' value. This [AoA] excursion beyond alpha prot caused a change in the pitch flight control law from normal law (Nz law) to angle of attack protection law (AoA law). If both sidesticks are at neutral, the AoA protection law seeks to hold the [AoA] constant at alpha prot until a sidestick pitch command is made."
Quote from HN39 (my emphasis):
My understanding is that activation/deactivation of any protection is recorded by the DFDR by a dedicated discrete parameter changing from OFF to ON, from ZERO to ONE, or whatever, and vice versa. I think it would have been a very strange omission if overspeed protection had been activated and caused the pitch-up and the AAIB report had made no mention of that fact.
Thanks for making that point.
The change to AOA protection mode disengagement was done through MOI in 2005. With this software change AOA protection is no longer active when alpha is less than alpha prot and side stick has not been deflected since the last autopilot disconnection.
Quote from my response:
Have you quoted the MOI in 2005 verbatim? If so, in an identical repeat of the A340 AIRPROX of 2001, it would have prevented the engagement of AoA mode (referred to by the AAIB as AoA protection Law). Taken literally, that would represent a radical inhibition of engagement, not an additional means of disengagement.
If, on the other hand, "is no longer active" actually means "will disengage", it would be an additional means (condition, or criterion) for disengagement. But it would not apply if either sidestick had been moved during a period of hand flying. That would seem odd, but perhaps I'm overlooking something.
Reply from vilas:
...I have quoted the MOI verbatim.
Thanks, vilas. Like OwainG, I am not familiar with (or have forgotten!) the term "MOI", but I presume it's a publication for informing operators of technical mods?
In my response, I overlooked a second possible inference that might be made from the MOI. I refer to this mid-sentence phrase:
"...AOA protection is no longer active when alpha is less than alpha prot ..."
Does it mean that, by 2005 (about 4 years after the A340 AIRPROX), AI had discontinued the phase-advanced engagement of AoA mode ("AoA protection Law") cited in the AAIB Bulletin of 2001? Page 11:
"Ten seconds after the autopilot disengaged, the corrected or phase-advanced angle of attack (a computed parameter which is is not recorded but can be calculated by [AI] from the DFDR data) reached the 'alpha prot' value. This [AoA] excursion beyond alpha prot caused a change in the pitch flight control law from normal law (Nz law) to angle of attack protection law (AoA law). If both sidesticks are at neutral, the AoA protection law seeks to hold the [AoA] constant at alpha prot until a sidestick pitch command is made."
Quote from HN39 (my emphasis):
My understanding is that activation/deactivation of any protection is recorded by the DFDR by a dedicated discrete parameter changing from OFF to ON, from ZERO to ONE, or whatever, and vice versa. I think it would have been a very strange omission if overspeed protection had been activated and caused the pitch-up and the AAIB report had made no mention of that fact.
Thanks for making that point.
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@OG - the only person claiming that the (permanent) disconnect didn't happen is one Christian Roger - SNPL member, card carrying member of the "cover-up" conspiracist crew, and member of Asseline's legal team.
It would appear that CONF iture is quoting assertions from this man's report as though they are fact.
However - this of course has nothing to do with the subject at hand, so moving swiftly on...
It would appear that CONF iture is quoting assertions from this man's report as though they are fact.
However - this of course has nothing to do with the subject at hand, so moving swiftly on...
Last edited by DozyWannabe; 12th Nov 2013 at 13:31.
Yeah Chris and others, the A-7 was truly called Sluf for Short Little Ugly "Feller". And staying off-topic a bit, we pilots in the first F-16 unit voted on "Viper". USAF didn't want a jet named after a reptile, so it became "Fighting Falcon" ( a civilian jet already had taken "Falcon").
The Sluf stick had a grip which contained force tranducers, and they used one for the prototype Viper FBW system with extra transducers. What they did was provide "augmented" commands to the control surfaces, and on check flights I could hold the stick between my knees and command roll and pitch by twisting the grip. So we were well on our way to FBW bacg in the late 60's. Pretty sure the Hornet has similar implementation, although their stick moves like the 'bus.
As Doze has iterated, pure "force feedback" has been absent for many years except a few implentations that use cables or pushrods for a limited number of surfaces. So anyone wishing for the "old days" are SOL. Only the Phantom and VooDoo had a pnematic bellows that kept you from pulling too hard at ridiculous high Q that the heavies cannot imagine, heh heh. Otherwise it was springs and things resembling shock absorbers to slow down rates and keep us from ripping the wings off.
I am still shocked that the AoA limits on the 'bus aren't active as long as the sensors are deemed reliable. So I learn a lotta stuff much of my time here.
Secondly, the overspeed "protection" features seem excessive, but the critical mach seems to be the "driver". I have also learned here just how close to edge of the envelope the thing flies. Surprised me, as we cruised well below our critical mach in the sub-sonic A-7 and A-37.
The Sluf stick had a grip which contained force tranducers, and they used one for the prototype Viper FBW system with extra transducers. What they did was provide "augmented" commands to the control surfaces, and on check flights I could hold the stick between my knees and command roll and pitch by twisting the grip. So we were well on our way to FBW bacg in the late 60's. Pretty sure the Hornet has similar implementation, although their stick moves like the 'bus.
As Doze has iterated, pure "force feedback" has been absent for many years except a few implentations that use cables or pushrods for a limited number of surfaces. So anyone wishing for the "old days" are SOL. Only the Phantom and VooDoo had a pnematic bellows that kept you from pulling too hard at ridiculous high Q that the heavies cannot imagine, heh heh. Otherwise it was springs and things resembling shock absorbers to slow down rates and keep us from ripping the wings off.
I am still shocked that the AoA limits on the 'bus aren't active as long as the sensors are deemed reliable. So I learn a lotta stuff much of my time here.
Secondly, the overspeed "protection" features seem excessive, but the critical mach seems to be the "driver". I have also learned here just how close to edge of the envelope the thing flies. Surprised me, as we cruised well below our critical mach in the sub-sonic A-7 and A-37.
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@vilas
Thank you, but a little more detail would be helpful since I cannot trace anything on the 'net'
Do you have a URL where the whole article can be read? Who is the MOI published by?
Airbus? or is it an unofficial document of some sort?
Modification operational Impact
Do you have a URL where the whole article can be read? Who is the MOI published by?
Airbus? or is it an unofficial document of some sort?
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BEA Report 3
1.12.4.2.1 3 Flightdeck Seats
On the RH-seat, there were no seatbelts fastened whatsover.
The most plausible scenario:
When Dubois asked Bonin if he had a licence -"T'as le PL, toi?" - just before he exited the flightdeck, Robert was already sitting on the LH-seat.
The hashed - censored DCVR- omits the fact that all 3 were discussing the answer of the licence and the only word that officially was allowed to come out was Dubois' reply of "Bon".
What followed before "Bon" and shortly after "Bon" is censored.
Bonin was napping when the A/P cut-off and in the ensuing alarms, panicked and accidentally used the S/S to pull himself out of his reclined position.
This caused the violent NU.
The following 3 minutes, absorbed by panic and impending tragedy, he didn't have time to adjust his seat or to stick one of his belts on.
Dubois wasn't seated on the jumpseat but someone else, most probably Mme Bonin.
This could further explain why Bonin refused to relinquish his grip on the S/S as matter of pride.
Dubois was seated with PAX when he felt the NU and swaying.
He didn't hear the buzzer because he wasn't in the CRA.
What were his first words as entered the flightdeck?
Not "what's up guys?" but "what the hell are you doing!"
On the RH-seat, there were no seatbelts fastened whatsover.
The most plausible scenario:
When Dubois asked Bonin if he had a licence -"T'as le PL, toi?" - just before he exited the flightdeck, Robert was already sitting on the LH-seat.
The hashed - censored DCVR- omits the fact that all 3 were discussing the answer of the licence and the only word that officially was allowed to come out was Dubois' reply of "Bon".
What followed before "Bon" and shortly after "Bon" is censored.
Bonin was napping when the A/P cut-off and in the ensuing alarms, panicked and accidentally used the S/S to pull himself out of his reclined position.
This caused the violent NU.
The following 3 minutes, absorbed by panic and impending tragedy, he didn't have time to adjust his seat or to stick one of his belts on.
Dubois wasn't seated on the jumpseat but someone else, most probably Mme Bonin.
This could further explain why Bonin refused to relinquish his grip on the S/S as matter of pride.
Dubois was seated with PAX when he felt the NU and swaying.
He didn't hear the buzzer because he wasn't in the CRA.
What were his first words as entered the flightdeck?
Not "what's up guys?" but "what the hell are you doing!"
Last edited by Winnerhofer; 12th Nov 2013 at 23:05.