He stepped on the Rudder and redefined Va
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Originally Posted by Teldorserious
Rabbit by your own post you mentioned that your NTSB guys show you the real deal but offical findings are different, for reasons you can't fathom. It's called politics and economics.
Here is a link to the Summary of this accident. From this page you will be able to download a full copy of the report ... if you are interested.
Accident Investigations - NTSB - National Transportation Safety Board
Last edited by AirRabbit; 30th Sep 2013 at 03:06.
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Air - Their report will say the pilots shouldn't use too much rudder...but what isn't in the report is that Airbus has quietly inspected, fixed, and stiffened up all the tails.
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air rabbit
the transports I fly DO have placards for gear extension speeds and flap speeds. don't yours?
and speeds for failure of rudder limiter to engage and for rudder limiter to disengage are all right there.
methinks you protect airbus too much.
and yes I've flown a transport cat plane that did have a placard for the following: do not use more than half control wheel throw above FL400
all sorts of things happen in real life...we even had a special provision for the flight attendants to NOT wear high heal shoes as they were damaging the floorboards in the cabin.
wake up to reality
a plane crashed, pilot blamed
but enough other pilots have spoken up on this forum and in other places to make everyone wonder.
SHEESH
the transports I fly DO have placards for gear extension speeds and flap speeds. don't yours?
and speeds for failure of rudder limiter to engage and for rudder limiter to disengage are all right there.
methinks you protect airbus too much.
and yes I've flown a transport cat plane that did have a placard for the following: do not use more than half control wheel throw above FL400
all sorts of things happen in real life...we even had a special provision for the flight attendants to NOT wear high heal shoes as they were damaging the floorboards in the cabin.
wake up to reality
a plane crashed, pilot blamed
but enough other pilots have spoken up on this forum and in other places to make everyone wonder.
SHEESH
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Guys, guys, Teldiserous is the latest incarnation of SSG and has never sat behind the controls of ANY aircraft. A flight simmer at best, and has proven time after time to have little to no understanding of aircraft ops.
I'm no troll as he claims, if anyone should have doubts I'll happily put those doubts to rest.
I'm no troll as he claims, if anyone should have doubts I'll happily put those doubts to rest.
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Please contain your comments to things pertinent to the thread's subject matter. Brian's comments may irritate you but they don't get to the point of being offensive. Certainly, you have a right of reply but not open slather to be offensive.
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How about a hypothetical conversation with an Airbus test pilot -
'How did you determine Va'
'How did you determine Va'
Va = Vs * sqrt(n).
No Rocket Science, not brand related.
Line Ops
Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident in which one or more of the main contributors, usually of dubious credentials and having lost the logical part of the argument, didn't resort to the usual accusations of corruption and collusion on the part of the manufacturer/regulator/investigator? I'm not holding my breath. 
For those who haven't flown big jets yet, and who may be impressed by all the derring-do being pedalled by some contributors here, here's my humble line-pilot experience - for what it's worth.
In the period (1971 - 2001) that I flew six different types of swept-wing big jets for a living on boring, public-transport operations, I never used the rudder except to:
(1) keep the a/c straight on T/O (backed up, if necessary, with into-wind aileron but without "cracking" the roll spoilers);
(2) to help induce a mild sideslip just before the flare when using the wing-down crosswind-landing technique (not on the B707!);
(3) to decrab, as necessary, on a crosswind landing;
(4) to keep the a/c straight during the landing run;
(5) to counter asymmetric thrust following an engine failure.
Note that only (1) and (4) involved rapid reversal of input, and only on the ground at low airspeeds. There were one or two colleagues who would use a bit of rudder to increase the rate of entry into a turn (usually when they were trying to captutre the ILS localiser), but this was frowned upon because it involved sideslip. Except in (2), and a little bit in (5), you do not induce sideslip on a big jet, partly because it is uncomfortable for the passengers and cabin crew. But in any case, it is simply bad flying. We do not need full rudder to pick up a wing in a stall because:
(a) IIRC, certification demands that aileron is usable (and recommended) in the recovery from a simple stall;
(b) we do not stall the aeroplane in public transport ops. However, in the extreme case, a stall normally occurs at a low airspeed.
Can I repeat another point I tried to make in a previous post? The A300-600 flight controls and tail-assembly structure are similar to the A310 I flew in the 1980s, although the VS dimensions may be slightly different.
Despite what flarepath would lead us to believe, there is a rudder travel limiter which becomes effective above a certain IAS (a bit above minimum-clean speed, IIRC). That limiter is a fuction of two computers called FACs. If it fails, the ECAM system (which was pioneered on the A310), announces something like "F/CTL: Rudder travel Limit INOP. Use rudder with care above xxx kt." This is accompanied by a master-caution W/L and a SC (single chime). Very similar to the A320 and its successors.
What the above-mentioned contributors are also in denial about is that, despite being reminded by tdracer and others, Boeing has quite clearly recognised the need to warn pilots not to cycle the rudder from stop to stop on its own airplanes. But who ever did?
Owain, I'm wondering if the B52 may have ailerons and elevators that use balance panels like the B707? In which case loss of hydraulics with the rudder, which may have an hydraulic booster like the B707, would not affect them. The main point about that a/c was that, as Armchairflyer says and you would know far better than I do, there was enough of the fin left to provide some degree of directional stability (unlike that B747 in Japan, caused by a botched repair to the rear pressure bulkhead).
For those who haven't flown big jets yet, and who may be impressed by all the derring-do being pedalled by some contributors here, here's my humble line-pilot experience - for what it's worth.
In the period (1971 - 2001) that I flew six different types of swept-wing big jets for a living on boring, public-transport operations, I never used the rudder except to:
(1) keep the a/c straight on T/O (backed up, if necessary, with into-wind aileron but without "cracking" the roll spoilers);
(2) to help induce a mild sideslip just before the flare when using the wing-down crosswind-landing technique (not on the B707!);
(3) to decrab, as necessary, on a crosswind landing;
(4) to keep the a/c straight during the landing run;
(5) to counter asymmetric thrust following an engine failure.
Note that only (1) and (4) involved rapid reversal of input, and only on the ground at low airspeeds. There were one or two colleagues who would use a bit of rudder to increase the rate of entry into a turn (usually when they were trying to captutre the ILS localiser), but this was frowned upon because it involved sideslip. Except in (2), and a little bit in (5), you do not induce sideslip on a big jet, partly because it is uncomfortable for the passengers and cabin crew. But in any case, it is simply bad flying. We do not need full rudder to pick up a wing in a stall because:
(a) IIRC, certification demands that aileron is usable (and recommended) in the recovery from a simple stall;
(b) we do not stall the aeroplane in public transport ops. However, in the extreme case, a stall normally occurs at a low airspeed.
Can I repeat another point I tried to make in a previous post? The A300-600 flight controls and tail-assembly structure are similar to the A310 I flew in the 1980s, although the VS dimensions may be slightly different.
Despite what flarepath would lead us to believe, there is a rudder travel limiter which becomes effective above a certain IAS (a bit above minimum-clean speed, IIRC). That limiter is a fuction of two computers called FACs. If it fails, the ECAM system (which was pioneered on the A310), announces something like "F/CTL: Rudder travel Limit INOP. Use rudder with care above xxx kt." This is accompanied by a master-caution W/L and a SC (single chime). Very similar to the A320 and its successors.
What the above-mentioned contributors are also in denial about is that, despite being reminded by tdracer and others, Boeing has quite clearly recognised the need to warn pilots not to cycle the rudder from stop to stop on its own airplanes. But who ever did?
Owain, I'm wondering if the B52 may have ailerons and elevators that use balance panels like the B707? In which case loss of hydraulics with the rudder, which may have an hydraulic booster like the B707, would not affect them. The main point about that a/c was that, as Armchairflyer says and you would know far better than I do, there was enough of the fin left to provide some degree of directional stability (unlike that B747 in Japan, caused by a botched repair to the rear pressure bulkhead).
Last edited by Jetdriver; 30th Sep 2013 at 16:14.
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Chris,
I really don't know much about the details of B52 design. I am going from this extract taken from the B52 history site:
That suggests to me that they may have retained roll and pitch controls - I note that there is no mention of a power pack supplying hydraulics to the rudder, but as I said, I am looking for confirmation. This in contradistinction to the A300 which would definitely have been without any form of control.
As to flight without a rudder, I think the vestigial fin left on that B52 would not have added much directional stability. OTOH, the B52 had a lot more fuselage aft of the wing root than ahead of it. My experience (strictly ground based!) would suggest that aircraft with highly swept wings can be flown without a fin, although they might wallow quite a bit ("interesting" dutch roll characteristics!) and one wouldn't want to attempt anything more than very gentle turns. Engine failures would be a definite no-no.
Bottom line is that the B52 survived, so it must be possible in at least one case.
I really don't know much about the details of B52 design. I am going from this extract taken from the B52 history site:
An unusual feature of the B-52 was the use of a pneumatic system as the primary power source in the operation of all auxiliary functions aboard the aircraft. High pressure, high temperature air was bled from the second stage compressor of each jet engine, and carried by ducts to the desired locality in the aircraft where it was transformed into electrical or hydraulic energy by air turbine-driven power packs. There were ten turbine-driven hydraulic pumps which supplied pressure at 3000 pounds per square inch to drive the brakes, steering mechanism, spoilers, bomb bay doors, and the adjustable stabilizer. The pneumatic system also drove air turbine alternators which provided the electrical power for the aircraft.
As to flight without a rudder, I think the vestigial fin left on that B52 would not have added much directional stability. OTOH, the B52 had a lot more fuselage aft of the wing root than ahead of it. My experience (strictly ground based!) would suggest that aircraft with highly swept wings can be flown without a fin, although they might wallow quite a bit ("interesting" dutch roll characteristics!) and one wouldn't want to attempt anything more than very gentle turns. Engine failures would be a definite no-no.
Bottom line is that the B52 survived, so it must be possible in at least one case.
Originally Posted by bubbers44
Yes, I know the rudder deflections on FDR but as I said recently my friend had uncomanded out of control deflections and they were not touching the rudders in their A300.
Originally Posted by bubbers44
Whatever! That is what happened.
Originally Posted by Teldorserious
what isn't in the report is that Airbus has quietly inspected, fixed, and stiffened up all the tails.
Quote from Owain Glyndwr:
As to flight without a rudder, I think the vestigial fin left on that B52 would not have added much directional stability. OTOH, the B52 had a lot more fuselage aft of the wing root than ahead of it. My experience (strictly ground based!) would suggest that aircraft with highly swept wings can be flown without a fin, although they might wallow quite a bit ("interesting" dutch roll characteristics!) and one wouldn't want to attempt anything more than very gentle turns. Engine failures would be a definite no-no.
Point taken. Very different fuselage profile from the B747...
As to flight without a rudder, I think the vestigial fin left on that B52 would not have added much directional stability. OTOH, the B52 had a lot more fuselage aft of the wing root than ahead of it. My experience (strictly ground based!) would suggest that aircraft with highly swept wings can be flown without a fin, although they might wallow quite a bit ("interesting" dutch roll characteristics!) and one wouldn't want to attempt anything more than very gentle turns. Engine failures would be a definite no-no.
Point taken. Very different fuselage profile from the B747...
That was prior to the B52G models which did away with the bleed air feed services. A lot if leaks that sent hit air thru all kinds of places it didn't belong. That said, the "finless" BUFF was an early model.
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It's not about brand B being tougher than brand A and never was. While the 747SP deserves kudos for hanging together in that China Airlines incident, you're talking about a completely different scenario causing completely different load factors on the airframe.
That incident involved a spiral dive - to cut a long description short, the torsional/bending loads are spread across the airframe and occur primarily to structures with spars, such as the wings and horizontal stab. The vertical stab will take some heavy punishment, but the loads only occur in one direction. Reversed sideslips of the kind that brought down AA587 apply almost all the torsion loads to the vertical stab - which is dangerous enough, but when you add in the reversals it quickly becomes more than any design of that size and that nature can handle.
As the photo earlier in the thread shows, not even the 747 has a spar or structural member going from the fuselage to the vertical stab. Like the A300 and pretty much every other aircraft of the type, the vertical stab is simply bolted on through lugs.
Brian - thanks for the clarification on the identity of our FUD merchant.
Utter rubbish. Inspected and fixed those that needed fixing yes, but there was no programme to "quietly" make changes to all of them because it simply wasn't necessary.
@Chris Scott - Amen!
That incident involved a spiral dive - to cut a long description short, the torsional/bending loads are spread across the airframe and occur primarily to structures with spars, such as the wings and horizontal stab. The vertical stab will take some heavy punishment, but the loads only occur in one direction. Reversed sideslips of the kind that brought down AA587 apply almost all the torsion loads to the vertical stab - which is dangerous enough, but when you add in the reversals it quickly becomes more than any design of that size and that nature can handle.
As the photo earlier in the thread shows, not even the 747 has a spar or structural member going from the fuselage to the vertical stab. Like the A300 and pretty much every other aircraft of the type, the vertical stab is simply bolted on through lugs.
Brian - thanks for the clarification on the identity of our FUD merchant.
Airbus has quietly inspected, fixed, and stiffened up all the tails.
Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident...
Last edited by DozyWannabe; 30th Sep 2013 at 14:07.
Chris, regarding:
Reading some of the vitriol that passes for "discussion", one wonders what airlines spent all that time and money on CRM for and why, that is, if indeed those contributing are actually transport pilots.
I second your comments which are very well stated, (specifically, points 1 - 5, & a-b), regarding rudder use. Your comments characterize and reflect my own experience in handling transport aircraft.
Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident in which one or more of the main contributors, usually of dubious credentials and having lost the logical part of the argument, didn't resort to the usual accusations of corruption and collusion on the part of the manufacturer/regulator/investigator? I'm not holding my breath.
I second your comments which are very well stated, (specifically, points 1 - 5, & a-b), regarding rudder use. Your comments characterize and reflect my own experience in handling transport aircraft.
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Originally Posted by flarepilot
the transports I fly DO have placards for gear extension speeds and flap speeds. don't yours
and speeds for failure of rudder limiter to engage and for rudder limiter to disengage are all right there.
methinks you protect airbus too much.
and yes I've flown a transport cat plane that did have a placard for the following: do not use more than half control wheel throw above FL400
and speeds for failure of rudder limiter to engage and for rudder limiter to disengage are all right there.
methinks you protect airbus too much.
and yes I've flown a transport cat plane that did have a placard for the following: do not use more than half control wheel throw above FL400
Originally Posted by flarepilot
wake up to reality
a plane crashed, pilot blamed
but enough other pilots have spoken up on this forum and in other places to make everyone wonder.
SHEESH
a plane crashed, pilot blamed
but enough other pilots have spoken up on this forum and in other places to make everyone wonder.
SHEESH
Did the AAMT course once offered by AA have anything to do with the magnitude of response used in this second encounter? I don’t know. And I don’t think anyone can say for sure. I know that the AAMT course did discuss the use of the rudder – but as I recall my exposure to that particular course (and no, I wasn’t employed by AA), was that the use of the rudder would be appropriate to assist in bringing the nose back to the horizon if using down-elevator was inappropriate or ineffectual after reaching an unacceptably high pitch attitude. Once achieving an angle of bank, pressuring the bottom rudder would bring the nose back to the desired attitude with respect to the horizon. I am also aware that AA did modify the content of this course to be sure that they weren’t encouraging an inordinate use of the rudder – and, I understand, eventually dropped the course altogether. However, if this course did contribute to the accident, it would leave open the question as to why the substantial use of rudder seen prior to the separation of the vertical tail did not occur during the first wingtip vortex encounter?
I hope this clarifies my comments for you.
Moderator
Wouldn't it be nice - particularly on Tech Log - to see a dispassionate debate on the causes of an accident...
Sometimes we mod folks tear our hair out trying to tread that fine line between too much interference (stifling debate to the point of overt censorship) and seeing some folk get too excited (too far beyond the reasonable bounds of polite discussion).
The only alternative to getting the balance wrong on most occasions .. is going fishing, I guess. Consequence of being a fallible human.
Sometimes we mod folks tear our hair out trying to tread that fine line between too much interference (stifling debate to the point of overt censorship) and seeing some folk get too excited (too far beyond the reasonable bounds of polite discussion).
The only alternative to getting the balance wrong on most occasions .. is going fishing, I guess. Consequence of being a fallible human.
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@AirRabbit
I doff my cap to you for a thoughtful, well-reasoned and insightful post.
One thing I remember from the time was a BBC Horizon documentary that stated a significant number of that FO's colleagues on AA's A300 fleet had transferred to Boeing types because they believed whole-heartedly in the "weak tail" scenario. Such actions speak to camaraderie and loyalty and they are no doubt noble, even if the evidence points elsewhere.
But if we are to be rational about things then we must follow the evidence, even if we don't like where it may lead. Heaven knows I've been accused enough times of "defending" or "protecting" Airbus when sticking to the evidence is all I've been doing. At the end of the day, even with the speculation over why the FO may have handled the rudder the way he appeared to, there is no arguing with the fact that the vertical stab did not fail until the forces on it exceeded the load limit by a factor of 2.2 times, exceeding the Ultimate load reserve by a factor of 1.47 times.
I doff my cap to you for a thoughtful, well-reasoned and insightful post.
One thing I remember from the time was a BBC Horizon documentary that stated a significant number of that FO's colleagues on AA's A300 fleet had transferred to Boeing types because they believed whole-heartedly in the "weak tail" scenario. Such actions speak to camaraderie and loyalty and they are no doubt noble, even if the evidence points elsewhere.
But if we are to be rational about things then we must follow the evidence, even if we don't like where it may lead. Heaven knows I've been accused enough times of "defending" or "protecting" Airbus when sticking to the evidence is all I've been doing. At the end of the day, even with the speculation over why the FO may have handled the rudder the way he appeared to, there is no arguing with the fact that the vertical stab did not fail until the forces on it exceeded the load limit by a factor of 2.2 times, exceeding the Ultimate load reserve by a factor of 1.47 times.
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I, along with a lot of other pilots on this thread, believe overiding an autopilot or autothrottle not doing what you want it to do is improper and should never be done on an Airbus because of Airbus policy.
I guess that is why I always flew Boeings because they were just an airplane and you could overide anything you chose to overide. I know I can correct a situation hand flying but Airbus says, NO, push this button. I think Airbus has made their pilots into flying robots. AF447 demonstrated this when all they needed was one pilot who knew how to hand fly but he was taking his break. Maybe he should have stayed in the cockpit to take care of the children of the magenta line. Pilots should always be pilots and not let the company make you into a computer operator.
I guess that is why I always flew Boeings because they were just an airplane and you could overide anything you chose to overide. I know I can correct a situation hand flying but Airbus says, NO, push this button. I think Airbus has made their pilots into flying robots. AF447 demonstrated this when all they needed was one pilot who knew how to hand fly but he was taking his break. Maybe he should have stayed in the cockpit to take care of the children of the magenta line. Pilots should always be pilots and not let the company make you into a computer operator.
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Originally Posted by john_tullamarine
Sometimes we mod folks tear our hair out trying to tread that fine line between too much interference (stifling debate to the point of overt censorship) and seeing some folk get too excited (too far beyond the reasonable bounds of polite discussion).
The only alternative to getting the balance wrong on most occasions .. is going fishing, I guess. Consequence of being a fallible human.
The only alternative to getting the balance wrong on most occasions .. is going fishing, I guess. Consequence of being a fallible human.
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Said document is here: http://www.airbus.com/fileadmin/medi..._SOP_SEQ02.pdf
and the relevant section is at the bottom of page 7.
If you read it in context, all it says is that a pilot should not try to override AP or A/THR by manipulating the controls without first explicitly using the disconnect button.
Note that it also says (emphasis mine):
If doubt exists regarding the aircraft flight path or
speed control, the flight crew should not try to reprogram the automated systems.
The flight crew should use Selected Guidance or hand flying together with the use of navaids raw data, until time and conditions permit a reprogramming of the AP/FD or FMS.
speed control, the flight crew should not try to reprogram the automated systems.
The flight crew should use Selected Guidance or hand flying together with the use of navaids raw data, until time and conditions permit a reprogramming of the AP/FD or FMS.
" You, sir, and this forum, deserve at least a handful of “atta-boys” for the kinds of information exchange you provide to all of us – and there’s probably no way to measure the value that has produced."
yessir, very well said, AR, +1
yessir, very well said, AR, +1