CABLE vs FBW
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DC-ATE,
With the title being "CABLE vs FBW" I have the impression you're barking up the wrong tree.
Most of the issues being discussed in Rumour & News have nothing to do with the way control surface deflection commands are transmitted from the pointy end to the left-and-right flappy bits and the blunt end, and everything with what the various computers do between the pilot's control inputs, either via a joystick, or a yoke, and the commands to the control surfaces.
I'll stay a moment with the "cable vs fly-by-wire", i.e., the transmission mode.
Cable isn't all that great. They rub and chafe (and can break...). They need a lot of rigging and regular adjustment. In a long aircraft, they tend to be affected by the simple fact that an aircraft isn't rigid (DC-8 comes to mind).
Not to mention that, more often than not, they are moved by a relay jack up front, and in turn they move servo valves on hydraulic power controls at the other end.... so there's no direct manual connection anyway.
Fly-by-wire as such, or "electrical signalling" as us oldies called it, is not exactly new, and neither is it rocket science.
The Vulcan used it, and so did Concorde, so we're talking 40 years plus....
Concorde had dual monitored signalling channels AND a mechanical back-up with cables, PLUS a control wheel steering mode (strain gauges) in case something jammed the cockpit controls.
While those modes were regularly trained for, I can't remember anybody describing a reversion to mechanical or to CWS on Concorde in normal service... a few reversions from 'blue' to 'green', yes, but that was about it.
So Concorde already pretty well settled the "cable vs electrical signalling" issue. On the A320 etc. the redundancy issue is settled by four separate "electrical signalling" channels, IIRC. No more mechanical back-up, but still a few tricks up the PIC's sleeve, just in case...
I readily admit to being an ancient, and not properly conversant with the control laws and logic on the A320 or on the B737NG (which usually lead to the A/B wars
). But I think the "cable vs FBW" notion as such is a non-issue. I would say that 'FBW' is mostly used as a misnomer for the various computer control modes used in the Airbus family.
Over to you.
CJ
With the title being "CABLE vs FBW" I have the impression you're barking up the wrong tree.
Most of the issues being discussed in Rumour & News have nothing to do with the way control surface deflection commands are transmitted from the pointy end to the left-and-right flappy bits and the blunt end, and everything with what the various computers do between the pilot's control inputs, either via a joystick, or a yoke, and the commands to the control surfaces.
I'll stay a moment with the "cable vs fly-by-wire", i.e., the transmission mode.
Cable isn't all that great. They rub and chafe (and can break...). They need a lot of rigging and regular adjustment. In a long aircraft, they tend to be affected by the simple fact that an aircraft isn't rigid (DC-8 comes to mind).
Not to mention that, more often than not, they are moved by a relay jack up front, and in turn they move servo valves on hydraulic power controls at the other end.... so there's no direct manual connection anyway.
Fly-by-wire as such, or "electrical signalling" as us oldies called it, is not exactly new, and neither is it rocket science.
The Vulcan used it, and so did Concorde, so we're talking 40 years plus....
Concorde had dual monitored signalling channels AND a mechanical back-up with cables, PLUS a control wheel steering mode (strain gauges) in case something jammed the cockpit controls.
While those modes were regularly trained for, I can't remember anybody describing a reversion to mechanical or to CWS on Concorde in normal service... a few reversions from 'blue' to 'green', yes, but that was about it.
So Concorde already pretty well settled the "cable vs electrical signalling" issue. On the A320 etc. the redundancy issue is settled by four separate "electrical signalling" channels, IIRC. No more mechanical back-up, but still a few tricks up the PIC's sleeve, just in case...
I readily admit to being an ancient, and not properly conversant with the control laws and logic on the A320 or on the B737NG (which usually lead to the A/B wars
). But I think the "cable vs FBW" notion as such is a non-issue. I would say that 'FBW' is mostly used as a misnomer for the various computer control modes used in the Airbus family.Over to you.
CJ
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FBW on the E-jets has two modes. An analogue "direct mode" with no software processing and an augmented "normal mode" where pilots inputs are summed with processed inputs from the flight control modules. Direct mode is nothing more than a multi channel replacement for cables where the pilot has full authority over the control surface. In this mode the only FBW v Cable argument can be weight and serviceability. FBW wins hands down in both.
Given the choice between cables and pullies or electronically signalled flight controls I'd take the latter.
Cables can fall off pullies and be easily jammed by loose objects.
Fly by wire or fly by light can seem to be an over complication, but in the case of civil aircraft the number of backup systems and modes covers the majority of eventualities.
Both control types on modern aircraft tend to have an artificial feel unit for powered control surfaces, so there is no improvement in the pilots feedback from the controls in the case of cables. In the case of more modern cable controlled powered control surfaces the cable only operates the hydraulic servos and offers no manual control of the surface in the event of a total hydraulics failure. Although there is often an electric trim tab
Of more interest to me is the processing of control inputs between the flght deck and the controls. The FBW systems can account for a higher number of variables than an arrangement of pulleys. This will hopefully lead to damage tollerant aircraft which can adapt to damage or failure of flight control systems. It also allows for a greater intigration of the automatics into the aircraft.
Cables can fall off pullies and be easily jammed by loose objects.
Fly by wire or fly by light can seem to be an over complication, but in the case of civil aircraft the number of backup systems and modes covers the majority of eventualities.
Both control types on modern aircraft tend to have an artificial feel unit for powered control surfaces, so there is no improvement in the pilots feedback from the controls in the case of cables. In the case of more modern cable controlled powered control surfaces the cable only operates the hydraulic servos and offers no manual control of the surface in the event of a total hydraulics failure. Although there is often an electric trim tab
Of more interest to me is the processing of control inputs between the flght deck and the controls. The FBW systems can account for a higher number of variables than an arrangement of pulleys. This will hopefully lead to damage tollerant aircraft which can adapt to damage or failure of flight control systems. It also allows for a greater intigration of the automatics into the aircraft.
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ChristiaanJ -
As I stated in another post, perhaps the "computer controlled" engines need to bne grouped in this discussion as well.
As to:
"(DC-8 comes to mind).
Not to mention that, more often than not, they are moved by a relay jack up front, and in turn they move servo valves on hydraulic power controls at the other end.... so there's no direct manual connection anyway."
That's not all true. The tabs are directly connect by cable. Read one of my previous posts.
And as to:
"Cable isn't all that great. They rub and chafe (and can break...). They need a lot of rigging and regular adjustment. In a long aircraft, they tend to be affected by the simple fact that an aircraft isn't rigid..."
Quite true. That's why there's periodic inspections.
And, I'm not interested in which aircraft are FBW/Computer controlled now or in the past. I'm trying to get some input on WHY folks think its SAFER.
And your:
"On the A320 etc. the redundancy issue is settled by four separate "electrical signalling" channels, IIRC. No more mechanical back-up, but still a few tricks up the PIC's sleeve, just in case..."
...points out the fact that they're not quite sure of themselves if they have to have that many back-ups.
On the DC-8.....CABLES were the back-up! Otherwise it was hydraulic power.
Your last:
"I would say that 'FBW' is mostly used as a misnomer for the various computer control modes used in the Airbus family."
I don't think it's a misnomer at all. It describes the system exactly: electric, read wire.
Gee...isn't this fun?!
As I stated in another post, perhaps the "computer controlled" engines need to bne grouped in this discussion as well.
As to:
"(DC-8 comes to mind).
Not to mention that, more often than not, they are moved by a relay jack up front, and in turn they move servo valves on hydraulic power controls at the other end.... so there's no direct manual connection anyway."
That's not all true. The tabs are directly connect by cable. Read one of my previous posts.
And as to:
"Cable isn't all that great. They rub and chafe (and can break...). They need a lot of rigging and regular adjustment. In a long aircraft, they tend to be affected by the simple fact that an aircraft isn't rigid..."
Quite true. That's why there's periodic inspections.
And, I'm not interested in which aircraft are FBW/Computer controlled now or in the past. I'm trying to get some input on WHY folks think its SAFER.
And your:
"On the A320 etc. the redundancy issue is settled by four separate "electrical signalling" channels, IIRC. No more mechanical back-up, but still a few tricks up the PIC's sleeve, just in case..."
...points out the fact that they're not quite sure of themselves if they have to have that many back-ups.
On the DC-8.....CABLES were the back-up! Otherwise it was hydraulic power.
Your last:
"I would say that 'FBW' is mostly used as a misnomer for the various computer control modes used in the Airbus family."
I don't think it's a misnomer at all. It describes the system exactly: electric, read wire.
Gee...isn't this fun?!
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The title, and therefore the whole argument of this thread is too -and by far - simplistic.
It should be about whether or not automation is necessary in our flight decks...and that's going very far back in time.
The main gripe of those arguing about FBW is the "out-of-the-loop" pilot discussion, but it is not a new one : with the big jets era, we've seen a lot of automated systems that were quite acceptable although they took a lot away from the guy in the nose ; to cite a few :
As for the engines, may I just remind the younger ones that the original 747 engine was so sensitive to throttle variations that they needed to be restrained in flight ?
All these systems, as I said have been quite welcomed by the pilot profession : A Mach trim acts without any pilot intervention but it was pretty important...so was the yaw damper...and no one questioned the usefulness of an antiskid although one could have one's foot to the pedal stop with not a single psi going to the brake cylinder ...
Were these protections a necessity ?
Well, just have a look at the AC DC-8 in Toronto when the crew thought wise to deploy the [b]ground spoilers/b] on landing....109 fatalities...
A quick research on the various accident data bases will show that cables and pullies were not that safe.
Now came the 320 and its followers along and aviation became another proposal altogether and the opponents became a lot more vocal (That thing is going to take away our skills...we're now truly out of the loop...)
Yeah ! Sure !
But people have a rather short memories : the so-called "hard limits" they were so against would have saved quite a few lives ; just two instances :
FBW C* laws are here to stay and I for one welcome them. Mind you, there could still be some gremlins hanging about in those softwares : One which is well known, and therefore designed into every system is about discrepancies between pilot inputs and response speeds from the controls....studied at length at Airbus Industries but they couldn't envisage the coupling that they got on the Bilbao incident (problem now solved).
On the other hand, I can't help but feel a bit sad that an accident that would have been avoided on a FBW equipped airliner happened on an MD-80 on August 16, 2005 with the loss of all aboard.
Just my two euro cents.
It should be about whether or not automation is necessary in our flight decks...and that's going very far back in time.
The main gripe of those arguing about FBW is the "out-of-the-loop" pilot discussion, but it is not a new one : with the big jets era, we've seen a lot of automated systems that were quite acceptable although they took a lot away from the guy in the nose ; to cite a few :
- Anti skid brakes
- Yaw dampers
- Air / Ground sensors allowing a config generated permission for brakes, steering, reversers...etc...
- Electronic auto-pilots and CWS modes allowing easier handling (the DC-10 uses it a lot)
As for the engines, may I just remind the younger ones that the original 747 engine was so sensitive to throttle variations that they needed to be restrained in flight ?
All these systems, as I said have been quite welcomed by the pilot profession : A Mach trim acts without any pilot intervention but it was pretty important...so was the yaw damper...and no one questioned the usefulness of an antiskid although one could have one's foot to the pedal stop with not a single psi going to the brake cylinder ...
Were these protections a necessity ?
Well, just have a look at the AC DC-8 in Toronto when the crew thought wise to deploy the [b]ground spoilers/b] on landing....109 fatalities...
A quick research on the various accident data bases will show that cables and pullies were not that safe.
Now came the 320 and its followers along and aviation became another proposal altogether and the opponents became a lot more vocal (That thing is going to take away our skills...we're now truly out of the loop...)
Yeah ! Sure !
But people have a rather short memories : the so-called "hard limits" they were so against would have saved quite a few lives ; just two instances :
- EAL DC-8 on a degraded stability in turbulence just after take-off...58 fatalities (25/2/64)
- JAL DC-8 in Moscow, with a "supercritical AoA" ... 61 fatalities (28/11/72)
FBW C* laws are here to stay and I for one welcome them. Mind you, there could still be some gremlins hanging about in those softwares : One which is well known, and therefore designed into every system is about discrepancies between pilot inputs and response speeds from the controls....studied at length at Airbus Industries but they couldn't envisage the coupling that they got on the Bilbao incident (problem now solved).
On the other hand, I can't help but feel a bit sad that an accident that would have been avoided on a FBW equipped airliner happened on an MD-80 on August 16, 2005 with the loss of all aboard.
Just my two euro cents.
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Just to add a little log to the fire, the 747 classic (and I suspect the -400) is all cable and pulleys from the control column to the hydraulic actuators, but if you lose all hydraulics, which is highly unlikely with 4 systems, you do not have any 'manual' back-up. You cannot move the controls by conventional cable link.
Does that mean it is fly by (cable) wire???
Rgds
CL747
Does that mean it is fly by (cable) wire???
Rgds
CL747
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It seems to me that Cables vs FBW misses something. There needs to be a third category. Some of the discussion here is treating "cables" as aircraft capable of a manual reversion where you can fly by actual cables attached to tabs that will move surfaces aerodynamically. And, on the other end meaning the Airbus FBW system.
In the Boeing line the 727's and 737's fit the "cable" definition, but the 747 does not. If all of the redundant hydraulic systems are drained, there is nothing tying pilot to surfaces, yet it is not FBW either.
There may be similar trust in cables and hydraulics, and less trust in computers and electrons by some in this discussion.
In the Boeing line the 727's and 737's fit the "cable" definition, but the 747 does not. If all of the redundant hydraulic systems are drained, there is nothing tying pilot to surfaces, yet it is not FBW either.
There may be similar trust in cables and hydraulics, and less trust in computers and electrons by some in this discussion.
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Lemurian =
"Well, just have a look at the AC DC-8 in Toronto when the crew thought wise to deploy the [b]ground spoilers/b] on landing....109 fatalities...
A quick research on the various accident data bases will show that cables and pullies were not that safe.
Now came the 320 and its followers along and aviation became another proposal altogether and the opponents became a lot more vocal (That thing is going to take away our skills...we're now truly out of the loop...)
Yeah ! Sure !
But people have a rather short memories : the so-called "hard limits" they were so against would have saved quite a few lives ; just two instances :
EAL DC-8 on a degraded stability in turbulence just after take-off...58 fatalities (25/2/64)
JAL DC-8 in Moscow, with a "supercritical AoA" ... 61 fatalities (28/11/72) "
-----
Toronto: nothing to do with the fact that it was cable operated.
Lake Pontchartrain: same thing.
Moscow: Don't have a report.
-----
".....DC-4 engine : valves here, valves there, a baro tube pushing a membrane which in turn pushes a rod that actuates the opening of yet another valve...and what did the "poppet valve do ?". They were brilliant pieces of engineering (just have a look of how the constant speed of a propeller was achieved !), but may I just remind you that not one of these marvels could qualify for the shortest ETOPS performance (If I remember well, the most beautiful of these machines, the Connie was also called "the best Trimotor over the Atlantic")."
-----
Ah.....brings tears to me eyes! Speeder spring and poppet valve. How 'bout the A, B, C, and D chambers?
The fact that the Connie MIGHT have been referred to as you say had nothing to do with the fact that it was cable operated.
-----
"On the other hand, I can't help but feel a bit sad that an accident that would have been avoided on a FBW equipped airliner happened on an MD-80 on August 16, 2005 with the loss of all aboard."
-----
If you're referring to West Caribbean Airways MD-82, I don't see where being cable operated had anything to do with that. They lost both engines. And, I'm not familiar with the MD-82 and whether it is controlled the same as the DC-8.
"Well, just have a look at the AC DC-8 in Toronto when the crew thought wise to deploy the [b]ground spoilers/b] on landing....109 fatalities...
A quick research on the various accident data bases will show that cables and pullies were not that safe.
Now came the 320 and its followers along and aviation became another proposal altogether and the opponents became a lot more vocal (That thing is going to take away our skills...we're now truly out of the loop...)
Yeah ! Sure !
But people have a rather short memories : the so-called "hard limits" they were so against would have saved quite a few lives ; just two instances :
EAL DC-8 on a degraded stability in turbulence just after take-off...58 fatalities (25/2/64)
JAL DC-8 in Moscow, with a "supercritical AoA" ... 61 fatalities (28/11/72) "
-----
Toronto: nothing to do with the fact that it was cable operated.
Lake Pontchartrain: same thing.
Moscow: Don't have a report.
-----
".....DC-4 engine : valves here, valves there, a baro tube pushing a membrane which in turn pushes a rod that actuates the opening of yet another valve...and what did the "poppet valve do ?". They were brilliant pieces of engineering (just have a look of how the constant speed of a propeller was achieved !), but may I just remind you that not one of these marvels could qualify for the shortest ETOPS performance (If I remember well, the most beautiful of these machines, the Connie was also called "the best Trimotor over the Atlantic")."
-----
Ah.....brings tears to me eyes! Speeder spring and poppet valve. How 'bout the A, B, C, and D chambers?
The fact that the Connie MIGHT have been referred to as you say had nothing to do with the fact that it was cable operated.
-----
"On the other hand, I can't help but feel a bit sad that an accident that would have been avoided on a FBW equipped airliner happened on an MD-80 on August 16, 2005 with the loss of all aboard."
-----
If you're referring to West Caribbean Airways MD-82, I don't see where being cable operated had anything to do with that. They lost both engines. And, I'm not familiar with the MD-82 and whether it is controlled the same as the DC-8.
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Centreline747 -
"Just to add a little log to the fire, the 747 classic (and I suspect the -400) is all cable and pulleys from the control column to the hydraulic actuators, but if you lose all hydraulics, which is highly unlikely with 4 systems, you do not have any 'manual' back-up. You cannot move the controls by conventional cable link.
Does that mean it is fly by (cable) wire??? "
That being the case (I'm not qualified on the 747), it's not cable operated in the same manner as the DC-8 is, is it?
"Just to add a little log to the fire, the 747 classic (and I suspect the -400) is all cable and pulleys from the control column to the hydraulic actuators, but if you lose all hydraulics, which is highly unlikely with 4 systems, you do not have any 'manual' back-up. You cannot move the controls by conventional cable link.
Does that mean it is fly by (cable) wire??? "
That being the case (I'm not qualified on the 747), it's not cable operated in the same manner as the DC-8 is, is it?
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DC-ATE
Are you a bit dishonest ? because if that's the case, there is no point at all in this discussion.
You advocate purely mechanical links between the pilot and the flight controls (plus or minus a hydraulic servo) and claim it was safer ("if it ain't broke, don't change it").
The three instances happened with unprotected flight controls, i.e. not FBW.
As for the MD-80, the flight controls of which are basicaly trim tabs, the crew couldn't manage a clean best glide angle, and speed, which could have helped a lot their relight attempts, and I'm not even talking about the characteristics of that airflow over the wing and it's influence on the engines'intakes....and they went down to crash on a series of consecutive stalls... It wouldn't have happened on an FBW airplane.
On th same subject, just imagine another unprotected airliner during the descent and ditching of USAir 1549...just 5 knots over stall speed but still under absolute control on all axises... If anything, that instance would make me a believer of the advantages of an FBW airplane.
Toronto: nothing to do with the fact that it was cable operated.
Lake Pontchartrain: same thing.
Moscow: Don't have a report.
Lake Pontchartrain: same thing.
Moscow: Don't have a report.
You advocate purely mechanical links between the pilot and the flight controls (plus or minus a hydraulic servo) and claim it was safer ("if it ain't broke, don't change it").
The three instances happened with unprotected flight controls, i.e. not FBW.
As for the MD-80, the flight controls of which are basicaly trim tabs, the crew couldn't manage a clean best glide angle, and speed, which could have helped a lot their relight attempts, and I'm not even talking about the characteristics of that airflow over the wing and it's influence on the engines'intakes....and they went down to crash on a series of consecutive stalls... It wouldn't have happened on an FBW airplane.
On th same subject, just imagine another unprotected airliner during the descent and ditching of USAir 1549...just 5 knots over stall speed but still under absolute control on all axises... If anything, that instance would make me a believer of the advantages of an FBW airplane.
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Originally Posted by Lemurian
....and they went down to crash on a series of consecutive stalls... It wouldn't have happened on an FBW airplane.
Fundamental confusion between FBW - fly-by-wire - as a concept, and what has been added since.
FBW as such has nothing to do with stall protection, etc.
In the olden days, we had fly-by-wire (see my earlier post), which just replaced less reliable and heavier wires.
In those days we had stick shakers, stick pushers and suchlike, as stall protection. Which you could ignore at your own discretion.... if you knew what you were doing.
Then came Alpha-Floor and all that, and if you didn't understand that, and didn't understand either that an engine needed time to spool up, and that you didn't do an "air show" below limits with a full load of passengers at an airfield you'd never been to before, yes.... you'd end up with something like Habsheim.
CJ
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Lemurian -
The Toronto accident was pilot error. The F/O actuated the spoilers 60' above ground on a DC-8.....strickly a NO, NO!
Lake Pontchartrain was an apparent failure of the PTC.
And, as I said, I don't have the info on the Moscow accident.
I won't discuss the MD82, because I know nothing about the DC-9 series A/C.
And as to:
"Are you a bit dishonest ? "
Would you care to elaborate on that remark?
The Toronto accident was pilot error. The F/O actuated the spoilers 60' above ground on a DC-8.....strickly a NO, NO!
Lake Pontchartrain was an apparent failure of the PTC.
And, as I said, I don't have the info on the Moscow accident.
I won't discuss the MD82, because I know nothing about the DC-9 series A/C.
And as to:
"Are you a bit dishonest ? "
Would you care to elaborate on that remark?
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DC-ATE :
On a 'Bus ( for instance), the ground spoilers would not deploy in an in-flight configuration, and in an alpha prot situation, the spoilers would have been retracted.
And btw, the co-pilot was only arming the ground spoilers, not extending them.
Wrong : the PTC had been MELed and was inoperative on that flight. The elevator position was from crew action (manual wheel).
The JAL DC-8 crashed in Moscow because of -another- spoiler extension just after takeoff, causing the AoA to increase beyond stall.
As to my remark, or my question, rather, it still stands : Are these accidents related to flight controls or not ?
Christiaanj
Sorry, Christiaanj, you can't dissociate the concept of FBW and the safety aspects it brought to our industry because they are at the heart of this discussion, some claiming their distrust of the concept, others with a different agenda. As a matter of fact, the protection concept appeared right at the beginning of the A300 test bed electrical signalling study : they were the natural inherent progression of the initial design. That Boeing chose a different path for its projects belongs to another discussion.
I have been flying the 'Bus for thirteen years now, after some experience on classic hydraulic-boosted flight controls - and some cable-and-pulleys- types and I've found the electrically signalled flight controls to be far superior, in terms of comfort, ease of flying, accuracy and safety.
This term of safety needs to be elaborated on a bit further : People only think of safety through the envelope protection of the different FBW realisations...OK, but the qualities I've eluded at also participate : flying with an always in-trim aircraft, with exactly the same perceived respone whatever the configuration or the speed takes a lot out of one's mind, making one quite a bit more available for the main task of flight management.
Please note that on my previous post I was already disputing the title of the thread, which should be more about flight deck automation -and its ultimate realisation : the FBW, envelope-protected airliner- rather than just replacing mechanical links with a bundle of electrical wires.
The problem goes far beyond that as there are moments when the task at hand exceeds one's capabilities : think of all the instances of windshear-caused accidents. Are they pilot errors ? Now compare the last instants of these cockpits with a "WINDSHEAR TOGA" maneuver in a 'Bus...didn't we make some real progress here by providing the guy in charge with an easier/safer tool which gives him the full maneuvering capability of the FBW system ?
All that said, I'm not naive enough to think for one second that FBW is the ultimate panacea and that it did not introduce a few traps in flying...Most of them are human factors-related : what confidence in the system, what about trust, what about complacency, and human-machine integration ?
I for one don't take anything for granted. I'm certainly not the only one around.
Onthat aspect, this study deserves some careful reading as it goes a lot beyond the "if it's not a DC-3, I won't take it"- type of argument :
Perceived Human Factor Problems In Flight-Deck Automation
The Toronto accident was pilot error. The F/O actuated the spoilers 60' above ground on a DC-8.....strickly a NO, NO!
And btw, the co-pilot was only arming the ground spoilers, not extending them.
Lake Pontchartrain was an apparent failure of the PTC.
The JAL DC-8 crashed in Moscow because of -another- spoiler extension just after takeoff, causing the AoA to increase beyond stall.
As to my remark, or my question, rather, it still stands : Are these accidents related to flight controls or not ?
Christiaanj
Fundamental confusion between FBW - fly-by-wire - as a concept, and what has been added since.
FBW as such has nothing to do with stall protection, etc.
I have been flying the 'Bus for thirteen years now, after some experience on classic hydraulic-boosted flight controls - and some cable-and-pulleys- types and I've found the electrically signalled flight controls to be far superior, in terms of comfort, ease of flying, accuracy and safety.
This term of safety needs to be elaborated on a bit further : People only think of safety through the envelope protection of the different FBW realisations...OK, but the qualities I've eluded at also participate : flying with an always in-trim aircraft, with exactly the same perceived respone whatever the configuration or the speed takes a lot out of one's mind, making one quite a bit more available for the main task of flight management.
Please note that on my previous post I was already disputing the title of the thread, which should be more about flight deck automation -and its ultimate realisation : the FBW, envelope-protected airliner- rather than just replacing mechanical links with a bundle of electrical wires.
In those days we had stick shakers, stick pushers and suchlike, as stall protection. Which you could ignore at your own discretion.... if you knew what you were doing.
All that said, I'm not naive enough to think for one second that FBW is the ultimate panacea and that it did not introduce a few traps in flying...Most of them are human factors-related : what confidence in the system, what about trust, what about complacency, and human-machine integration ?
I for one don't take anything for granted. I'm certainly not the only one around.
Onthat aspect, this study deserves some careful reading as it goes a lot beyond the "if it's not a DC-3, I won't take it"- type of argument :
Perceived Human Factor Problems In Flight-Deck Automation
I found the title of the thread quite unambiguous. it was really just questioning how the flying controls received their signals and was it relevant to the Hudson river incident.
Well, it was relevant in that the crew would have had the flying controls degraded two steps from Normal Law, through Alternate Law to Direct Law. This means that the controls move proportionally in realtion to the stick movement. Just like they would in a cable controlled aircraft such as an older Boeing design. The crew would have also lost a lot of the protections such as V alpha Max which would initiate an auto go around - if they still had engines!
So there is a difference, but it's no big deal and not of huge relevance. It just downgraded itself down to a 737!
Well, it was relevant in that the crew would have had the flying controls degraded two steps from Normal Law, through Alternate Law to Direct Law. This means that the controls move proportionally in realtion to the stick movement. Just like they would in a cable controlled aircraft such as an older Boeing design. The crew would have also lost a lot of the protections such as V alpha Max which would initiate an auto go around - if they still had engines!
So there is a difference, but it's no big deal and not of huge relevance. It just downgraded itself down to a 737!
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Lemurian -
"And btw, the co-pilot was only arming the ground spoilers, not extending them."
Ah...you yourself stated in #25:
"the crew thought wise to deploy the [b]ground spoilers/b] on landing...."
The F/O did not "arm" them; he EXTENDED them.
Are you being a bit dishonest?
Without reading the reports on the other two, I won't comment. I do recall something about the PTC being deferred. But so what? Stuff happens.
"And btw, the co-pilot was only arming the ground spoilers, not extending them."
Ah...you yourself stated in #25:
"the crew thought wise to deploy the [b]ground spoilers/b] on landing...."
The F/O did not "arm" them; he EXTENDED them.
Are you being a bit dishonest?
Without reading the reports on the other two, I won't comment. I do recall something about the PTC being deferred. But so what? Stuff happens.
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DC-ATE
So, stuff happens on a cable-and-pullies airplane and you find it acceptable and you refuse to consider any of the progress made through FBW...
To say the least, strange attitude !
OK, I'm out of here.
Technical discussions are alright, but this is turning to a dialogue of the deafs...my fault, I suppose.
Bye.
I do recall something about the PTC being deferred. But so what? Stuff happens.
To say the least, strange attitude !
OK, I'm out of here.
Technical discussions are alright, but this is turning to a dialogue of the deafs...my fault, I suppose.
Bye.
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Lemurian -
Two of the accidents you listed were the (apparent) result of PILOT ERROR. The fact that the spoilers are 'mechanical' really did not matter.
05 July 1970
Air Canada
Toronto, Ontario, Canada
60 feet above the ground during landing, the speedbrakes were inadvertantly deployed by the First Officer, which resulted in an excessive sink rate. The no.4 engine struck the runway, and a go-around was initiated. The aircraft proceeded to climb out normally, but while on a downwind for a second landing attempt, the aircraft exploded. Ruptured fuel line during the first hard landing.
28 November 1972
Japan Airlines
Moscow, Russia
The aircraft crashed on takeoff after the accidental deployment of the spoilers by the Flight Engineer.
"OK, I'm out of here.
Technical discussions are alright, but this is turning to a dialogue of the deafs...my fault, I suppose."
OK.....have a good day.
Two of the accidents you listed were the (apparent) result of PILOT ERROR. The fact that the spoilers are 'mechanical' really did not matter.
05 July 1970
Air Canada
Toronto, Ontario, Canada
60 feet above the ground during landing, the speedbrakes were inadvertantly deployed by the First Officer, which resulted in an excessive sink rate. The no.4 engine struck the runway, and a go-around was initiated. The aircraft proceeded to climb out normally, but while on a downwind for a second landing attempt, the aircraft exploded. Ruptured fuel line during the first hard landing.
28 November 1972
Japan Airlines
Moscow, Russia
The aircraft crashed on takeoff after the accidental deployment of the spoilers by the Flight Engineer.
"OK, I'm out of here.
Technical discussions are alright, but this is turning to a dialogue of the deafs...my fault, I suppose."
OK.....have a good day.
Only half a speed-brake
Could Cali CFIT had been avoided through last-stop measure of some SW logic auto-retracting speedbrakes when TO/GA thrust is set?
FD (the un-real)