LH A320 reportedly within 0.5m of crashing at FRA !!
Guest
Posts: n/a
Slightly off topic but...
I seem to remember a documentary about Airbus A320 and FBW incidents etc which had on it the ex Lufhthansa chief safety pilot being interviewed and if my memory serves me correct he actually resigned from LH in protest at their decision to buy these A/C.
Can anyone else confirm this? I'm fairly sure I'm right.
[This message has been edited by Pengineer (edited 05 June 2001).]
I seem to remember a documentary about Airbus A320 and FBW incidents etc which had on it the ex Lufhthansa chief safety pilot being interviewed and if my memory serves me correct he actually resigned from LH in protest at their decision to buy these A/C.
Can anyone else confirm this? I'm fairly sure I'm right.
[This message has been edited by Pengineer (edited 05 June 2001).]
Guest
Posts: n/a
411A & Ironbutt57 --- SOG's
Out of all of this I noticed that having had the wires changed on the CAPTAINS sidestick the engineer carries out the control check ( without external check) using the CO-PILOTS sidestick. Well excuse me but which one had the work carried out on it!!!!!!!!!!!!!!
------------------
Keep smiling!!!!
Out of all of this I noticed that having had the wires changed on the CAPTAINS sidestick the engineer carries out the control check ( without external check) using the CO-PILOTS sidestick. Well excuse me but which one had the work carried out on it!!!!!!!!!!!!!!
------------------
Keep smiling!!!!
Join Date: Jul 2000
Location: Hamburg,Germany
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There is something i wanted to ask about this incident, too:
If the wing was only still 0.5 feet (or meters) from the surface, how should it have lasted 5 more seconds (anyone wrote this) until impact ? Did the captain try to correct the course during rotation or after take off ? I can't believe that within 5 seconds a A320 shouldn't have made enough height to avoid touching the ground with a wing ? Who can say somnething about this point ?
Interestingly this incident isn't discussed on the german pilots site at the moment.
Makes me wonder .... so it's all right ?
cheers
ef
If the wing was only still 0.5 feet (or meters) from the surface, how should it have lasted 5 more seconds (anyone wrote this) until impact ? Did the captain try to correct the course during rotation or after take off ? I can't believe that within 5 seconds a A320 shouldn't have made enough height to avoid touching the ground with a wing ? Who can say somnething about this point ?
Interestingly this incident isn't discussed on the german pilots site at the moment.
Makes me wonder .... so it's all right ?
cheers
ef
Guest
Posts: n/a
PFD – sadly the independent checking system has all but disappeared in civil aviation.
Abulafia – CRM training had little to do with the F/O's input, more like lightning recognition of the situation and the application of common sense.
Pengineer – The man you refer to is a personal friend and former colleague of mine - Captain Heino H. Ceasar, indeed the former Chief Flight Safety Pilot at LH, and who left on attaining retirement age (from the B747-200) and not 'in protest' at LH's acquisition of Airbus equipment. He had lots of, shall we say, strong opinions, about all the products he flew, all the way back to long-range piston types.
Abulafia – CRM training had little to do with the F/O's input, more like lightning recognition of the situation and the application of common sense.
Pengineer – The man you refer to is a personal friend and former colleague of mine - Captain Heino H. Ceasar, indeed the former Chief Flight Safety Pilot at LH, and who left on attaining retirement age (from the B747-200) and not 'in protest' at LH's acquisition of Airbus equipment. He had lots of, shall we say, strong opinions, about all the products he flew, all the way back to long-range piston types.
Guest
Posts: n/a
pengineer:
I think I know the film you mentioned as I produced and directed it*. But you're wrong! To my knowledge the former Lufthansa CF, Cpt. Heino Caesar did not resign in protest. He simply retired reaching his retirement age.
Cpt. Caesar was involved in the early stage of the Lufthansa decision to go for the A320 as he was the company safety pilot. He published some quite remarkable articles with the FSF and other special publications in regards to automation in the cockpit and the man-machine interface.
Regards
TvB
* The film is titled "fatal logic" and is dealing with the Lufthansa landing accident in WAW and in general with the design philosophy of AI. This film was realized in cooperation with the German Pilots Union (VC) and tried to shed some light onto the line of notorious "pilot errors" - whenever it came to an Airbus accident.
Those who are interested in the further development of this story might check the article "Thinking of Airbus" under the "Special Features" section on my webpage at www.aviationsafetyonline.com
I think I know the film you mentioned as I produced and directed it*. But you're wrong! To my knowledge the former Lufthansa CF, Cpt. Heino Caesar did not resign in protest. He simply retired reaching his retirement age.
Cpt. Caesar was involved in the early stage of the Lufthansa decision to go for the A320 as he was the company safety pilot. He published some quite remarkable articles with the FSF and other special publications in regards to automation in the cockpit and the man-machine interface.
Regards
TvB
* The film is titled "fatal logic" and is dealing with the Lufthansa landing accident in WAW and in general with the design philosophy of AI. This film was realized in cooperation with the German Pilots Union (VC) and tried to shed some light onto the line of notorious "pilot errors" - whenever it came to an Airbus accident.
Those who are interested in the further development of this story might check the article "Thinking of Airbus" under the "Special Features" section on my webpage at www.aviationsafetyonline.com
Guest
Posts: n/a
there is no issue here .....
the control scenario is checked on the ground ( spoiler deflection & all aileron inputs ) ..... there is no error margin .....crew input ...& ecam confirmation .. think lufty is thingkin bout the xtra 30 % .....2 much......??
the control scenario is checked on the ground ( spoiler deflection & all aileron inputs ) ..... there is no error margin .....crew input ...& ecam confirmation .. think lufty is thingkin bout the xtra 30 % .....2 much......??
Guest
Posts: n/a
enginefailure:
check out the threat before you write. It starts at page 1. Everything was quoted here and as for the German Pilots Forum pls. check:
http://www.pilots.de/ubb/NonCGI/Forum1/HTML/000797.html
- if you understand German.
After all this cross- and double checking your engine should be running..., ehh...your questions should be answered.
Regards
------------------
check out the threat before you write. It starts at page 1. Everything was quoted here and as for the German Pilots Forum pls. check:
http://www.pilots.de/ubb/NonCGI/Forum1/HTML/000797.html
- if you understand German.
After all this cross- and double checking your engine should be running..., ehh...your questions should be answered.
Regards
------------------
Guest
Posts: n/a
Streamline;
I flew a few British airplanes when I was a youngun and I was not impressed with their manuals either. I am only talking here about Boeing really, since I am not aware of the Airbus manuals. But from what I have read here I can see that the tendency of airline managers to write procedures themselves exists in Airbus fleets too.
I know that for the latest generation of airplanes Boeing spent a lot of time and money to get the best procedures for their product, and the design of the systems and switches were optimised for those procedures so that everything works as well as it can. They had specialists in time and motion, engineering, flight crew (including trained and qualified test pilots), education, medicine and so on to conference, suggest, test and apply it all. The end result is what we, the greasy end, have to work with.
Yet many airlines don't even bother to try it before they substitute their own procedures. They have no idea what affect this will have on the safe or efficient operation of the airplane, and often are not aware of the damage they do. They justify it by saying it is "standardization", or it is intended to reduce training cost, or simply (usually) it is done because the old codger writing the new procedures does so to make it comfortable to himself.
It goes without saying that the airline managers and their helpers do not have the qualifications of those who designed the original procedures. The pilots accept the way the airline tells them to do it, and most of the time they are not aware of the deficiencies, nor even that what they are doing is not 'standard' (what the manufacturer intended).
If the changes were beneficial, then you can be assured that the manufacturer would pick them up and make them part of their own procedures. This practically does not happen, which should tell you something.
Many of the changes made do result, by themselves and as part of the whole procedure, in a less safe and less efficient way of doing it.
Changing the B744 procedures to agree in part with the 747 Classic, for example, is a terribly short sighted way to do it. But Lufthansa (among others) does exactly this.
The new airplanes are downgraded (dumbed down) for a short term benefit and once the procedures are written, it is extemely hard to change them.
Ansett bought new F27-400s with F27-100 flight instruments, for example, intending to save money on training, and I have heard some airlines have tried to do the same with the newer glass cockpit types (CX for one). This is an extreme example of what I am talking about of course, but even if the change is simply to move the control check to the taxi phase instead of doing it before start, as the manufacturer intended, has adverse affects on safety and cost.
In fact I know of no changes that result in an improvement. Maybe you do?
I flew a few British airplanes when I was a youngun and I was not impressed with their manuals either. I am only talking here about Boeing really, since I am not aware of the Airbus manuals. But from what I have read here I can see that the tendency of airline managers to write procedures themselves exists in Airbus fleets too.
I know that for the latest generation of airplanes Boeing spent a lot of time and money to get the best procedures for their product, and the design of the systems and switches were optimised for those procedures so that everything works as well as it can. They had specialists in time and motion, engineering, flight crew (including trained and qualified test pilots), education, medicine and so on to conference, suggest, test and apply it all. The end result is what we, the greasy end, have to work with.
Yet many airlines don't even bother to try it before they substitute their own procedures. They have no idea what affect this will have on the safe or efficient operation of the airplane, and often are not aware of the damage they do. They justify it by saying it is "standardization", or it is intended to reduce training cost, or simply (usually) it is done because the old codger writing the new procedures does so to make it comfortable to himself.
It goes without saying that the airline managers and their helpers do not have the qualifications of those who designed the original procedures. The pilots accept the way the airline tells them to do it, and most of the time they are not aware of the deficiencies, nor even that what they are doing is not 'standard' (what the manufacturer intended).
If the changes were beneficial, then you can be assured that the manufacturer would pick them up and make them part of their own procedures. This practically does not happen, which should tell you something.
Many of the changes made do result, by themselves and as part of the whole procedure, in a less safe and less efficient way of doing it.
Changing the B744 procedures to agree in part with the 747 Classic, for example, is a terribly short sighted way to do it. But Lufthansa (among others) does exactly this.
The new airplanes are downgraded (dumbed down) for a short term benefit and once the procedures are written, it is extemely hard to change them.
Ansett bought new F27-400s with F27-100 flight instruments, for example, intending to save money on training, and I have heard some airlines have tried to do the same with the newer glass cockpit types (CX for one). This is an extreme example of what I am talking about of course, but even if the change is simply to move the control check to the taxi phase instead of doing it before start, as the manufacturer intended, has adverse affects on safety and cost.
In fact I know of no changes that result in an improvement. Maybe you do?
Guest
Posts: n/a
There is an interesting analogy to non-standard wiring of flight control sticks in the field of anaesthesiology. It makes interesting reading and I quote from it below. Maybe someone in the aviation world can calculate the incremental reduction in risk that common design aspects across a family of aircraft could generate.
In the book ‘The best American Science writing 2000’, Atul Gawande writes about the incidence of fatalities resulting from general anaesthesia. In the US, between 1960 and 1980, this averaged at 1 in 10,000 operations. Acceptable risk? Maybe not if you weigh the ratio against total operations annually. In 1982, this equated to 6000 patient killed or brain damaged. Fortunately, the incidence is greatly reduced today, thanks to an engineer named Jeffrey Cooper. To quote from the book,
“An unassuming, fastidious man, Cooper had been hired in 1972, when he was twenty-six years old, by the Massachusetts General Hospital bioengineering unit, to work on developing machines for anesthesiology researchers. He gravitated toward the operating room, however, and spent hours there observing the anesthesiologists, and one of the first things he noticed was how poorly the anesthesia machines were designed. For example, a clockwise turn of a dial decreased the concentration of potent anesthetics in about half the machines but increased the concentration in the other half. He decided to borrow a technique called "critical incident analysis"--which had been used since the nineteen-fifties to analyze mishaps in aviation--in an effort to learn how equipment might be contributing to errors in anesthesia. The technique is built around carefully conducted interviews, designed to capture as much detail as possible about dangerous incidents: how specific accidents evolved and what factors contributed to them. This information is then used to look for patterns among different cases.
Getting open, honest reporting is crucial. The Federal Aviation Administration has a formalized system for analyzing and reporting dangerous aviation incidents, and its enormous success in improving airline safety rests on two cornerstones. Pilots who report an incident within ten days have automatic immunity from punishment, and the reports go to a neutral, outside agency, NASA, which has no interest in using the information against individual pilots. For Jeffrey Cooper, it was probably an advantage that he was an engineer, and not a physician, so that anesthesiologists regarded him as a discreet, unthreatening interviewer.
The result was the first in-depth, scientific look at errors in medicine. His detailed analysis of three hundred and fifty-nine errors provided a view of the profession unlike anything that had been seen before. Contrary to the prevailing assumption that the start of anesthesia ("takeoff") was the most dangerous part, anesthesiologists learned that incidents tended to occur in the middle of anesthesia, when vigilance waned. The most common kind of incident involved errors in maintaining the patient's breathing, and these were usually the result of an undetected disconnection or misconnection of the breathing tubing, mistakes in managing the airway, or mistakes in using the anesthesia machine. Just as important, Cooper enumerated a list of contributory factors, including inadequate experience, inadequate familiarity with equipment, poor communication among team members, haste, inattention, and fatigue.
The study provoked widespread debate among anesthesiologists, but there was no concerted effort to solve the problems until Jeep Pierce came along. Through the anesthesiology society at first, and then through a foundation that he started, Pierce directed funding into research on how to reduce the problems Cooper had identified, sponsored an international conference to gather ideas from around the world, and brought anesthesia-machine designers into safety discussions.
It all worked. Hours for anesthesiology residents were shortened. Manufacturers began redesigning their machines with fallible human beings in mind. Dials were standardized to turn in a uniform direction; locks were put in to prevent accidental administration of more than one anesthetic gas; controis were changed so that oxygen delivery could not be turned down to zero.”
……”Today, anesthesia deaths from misconnecting the breathing system or intubating the esophagus rather than the trachea are virtually unknown. In a decade, the over-all death rate dropped to just one in more than two hundred thousand cases--less than a twentieth of what it had been.
Reference
Gawande, A., “When doctors make mistakes”, In “The best American science writing 2000”, Ed. James Gleick, ECCO Harper-Collins, New York 2000.
In the book ‘The best American Science writing 2000’, Atul Gawande writes about the incidence of fatalities resulting from general anaesthesia. In the US, between 1960 and 1980, this averaged at 1 in 10,000 operations. Acceptable risk? Maybe not if you weigh the ratio against total operations annually. In 1982, this equated to 6000 patient killed or brain damaged. Fortunately, the incidence is greatly reduced today, thanks to an engineer named Jeffrey Cooper. To quote from the book,
“An unassuming, fastidious man, Cooper had been hired in 1972, when he was twenty-six years old, by the Massachusetts General Hospital bioengineering unit, to work on developing machines for anesthesiology researchers. He gravitated toward the operating room, however, and spent hours there observing the anesthesiologists, and one of the first things he noticed was how poorly the anesthesia machines were designed. For example, a clockwise turn of a dial decreased the concentration of potent anesthetics in about half the machines but increased the concentration in the other half. He decided to borrow a technique called "critical incident analysis"--which had been used since the nineteen-fifties to analyze mishaps in aviation--in an effort to learn how equipment might be contributing to errors in anesthesia. The technique is built around carefully conducted interviews, designed to capture as much detail as possible about dangerous incidents: how specific accidents evolved and what factors contributed to them. This information is then used to look for patterns among different cases.
Getting open, honest reporting is crucial. The Federal Aviation Administration has a formalized system for analyzing and reporting dangerous aviation incidents, and its enormous success in improving airline safety rests on two cornerstones. Pilots who report an incident within ten days have automatic immunity from punishment, and the reports go to a neutral, outside agency, NASA, which has no interest in using the information against individual pilots. For Jeffrey Cooper, it was probably an advantage that he was an engineer, and not a physician, so that anesthesiologists regarded him as a discreet, unthreatening interviewer.
The result was the first in-depth, scientific look at errors in medicine. His detailed analysis of three hundred and fifty-nine errors provided a view of the profession unlike anything that had been seen before. Contrary to the prevailing assumption that the start of anesthesia ("takeoff") was the most dangerous part, anesthesiologists learned that incidents tended to occur in the middle of anesthesia, when vigilance waned. The most common kind of incident involved errors in maintaining the patient's breathing, and these were usually the result of an undetected disconnection or misconnection of the breathing tubing, mistakes in managing the airway, or mistakes in using the anesthesia machine. Just as important, Cooper enumerated a list of contributory factors, including inadequate experience, inadequate familiarity with equipment, poor communication among team members, haste, inattention, and fatigue.
The study provoked widespread debate among anesthesiologists, but there was no concerted effort to solve the problems until Jeep Pierce came along. Through the anesthesiology society at first, and then through a foundation that he started, Pierce directed funding into research on how to reduce the problems Cooper had identified, sponsored an international conference to gather ideas from around the world, and brought anesthesia-machine designers into safety discussions.
It all worked. Hours for anesthesiology residents were shortened. Manufacturers began redesigning their machines with fallible human beings in mind. Dials were standardized to turn in a uniform direction; locks were put in to prevent accidental administration of more than one anesthetic gas; controis were changed so that oxygen delivery could not be turned down to zero.”
……”Today, anesthesia deaths from misconnecting the breathing system or intubating the esophagus rather than the trachea are virtually unknown. In a decade, the over-all death rate dropped to just one in more than two hundred thousand cases--less than a twentieth of what it had been.
Reference
Gawande, A., “When doctors make mistakes”, In “The best American science writing 2000”, Ed. James Gleick, ECCO Harper-Collins, New York 2000.
Guest
Posts: n/a
Date: Mon, 18 Jun 2001 12:54:17 +0200
From: "Peter B. Ladkin" <[email protected]>
Subject: A320 Incident
Tim van Beveren reported in *Flight International*, 22-28 May 2001, on a 20
Mar 2001 incident to a Lufthansa Airbus A320 on takeoff from Frankfurt.
This incident was reported at greater length and detail in *Air Safety
Week*, 4 Jun 2001, by David Evans and Tim van Beveren.
The captain was Pilot Flying (PF). there was some degree of turbulence
during takeoff, shortly after rotation, which resulted in the left wing
moving down. The captain applied correction (right lateral roll control) but
the wing dipped further left, reaching 21 degrees bank, and the wingtip is
reported to have come within half a meter of the ground, and according to
computer modelling of the digital flight data recorder the airplane "came
within a few seconds of striking the ground".
The First Officer, the pilot not flying (PNF), realising there could be a
control problem, switched "priority" to his sidestick controller and
recovered the aircraft. The aircraft was flown up to 12,000ft on autopilot,
the crew confirmed the problem, that the CAP's sidestick was controlling for
roll in the reverse sense (normally, putting the sidestick to the left
commands left roll; to the right commands right roll. Control-reversal here
means that CAP's sidestick gave right roll on a left movement and left roll
on a right movement).
The aircraft had just come out of maintenance. Maintenance is a known
risk -- James Reason, an authority on human factors in aviation safety and
Professor of Psychology at the University of Manchester, amongst others, has
detailed how significant problems may arise through maintenance of complex
systems.
It has happened many times that aircraft have come out of maintenance with
control systems reversed in one or more of the three axes (roll, pitch,
yaw). This has been the cause of a number of accidents with general aviation
aircraft, but my informal requests for information turned up no recent
accidents to commercial aircraft due to this cause. Evans and van Beveren
report that "reversed controls are deemed impossible on transport-category
aircraft" and that Boeing claims that the B737 aircraft cannot be
reverse-connected without it being discovered before flight, normally
through mandatory post-maintenance checks, but at the latest by the pilot's
preflight check, as the controls could not be moved.
At Lufthansa's code-sharing partner, United Air Lines, certified inspectors
must be stationed both inside and outside the cockpit to conduct a
functional check after the flight control system has been worked on; a
flight test is also required before the aircraft is returned to service
after this kind of repair. It is believed that either of these measures
would have caught the control-reversal problem, and so general
maintenance
procedures at Lufthansa Technik will be subject to detailed inquiry.
There have been a number of reports as to what fault caused the lateral
control reversal, including the two sources above. However, I have found
none of the explanations so far satisfactory, as they raise further puzzles
that they do not solve.
The following architectural description of the A320 primary flight control
system (PFCS) is drawn from Cary R. Spitzer, Digital Avionics Systems,
Second Edition, McGraw-Hill 1993. The A320 sidestick controller generates
input to five of the seven flight control computers which form part of the
primary flight control system (PFCS). These five are the two Elevator
Aileron Computers (ELACs) and the three Spoiler Elevator Computers (SECs).
Each wing has two outboard ailerons, and five inboard spoilers (overwing
surfaces which can be raised). Lateral (roll) control proceeds via four of
the five spoilers and the two ailerons. Each of the two ELACS and three SECs
control some combination of these 12 control surfaces. There is a
significant amount of control redundancy.
Initial reports said that Lufthansa Technik personnel had been repairing
one of the two ELACs, and had found a damaged pin on a connector. They
had replaced the connector and this had apparently caused the control
reversal. This explanation made no sense to me as it stood, because
(a) the connectors are standardised. Replacing one with another should
give exactly the same connections as were there before;
(b) if one ELAC was receiving reversed signals, and the other was not,
and the three SECs were not, then
(i) the PFCS architecture would detect a discrepancy on the channels, and
(ii) on each side, one aileron would operate counter to the other, but
all spoilers would operate correctly-sensed, and it is hard to see
how this could lead to the extreme control discrepancy reportedly
experienced by the PF.
The Aviation Safety Week report on June 4 suggested that "Repair work
involving complete rewiring "upstream" of the connector pins was conducted
over several work shifts". The ELAC connector with the damaged pin has 140
pins and is one of four such for the ELAC, for a total of 560 pins.
It seems to me that to get control reversal without the phenomena in (b)
above, there must have been a reversed signal downstream of the sidestick
but upstream of where the sidestick movement is multiplexed into the five
input signals to the five PFCS computers which receive them. I do not yet
have, nor have I heard, a coherent suggestion as to how that could occur.
There has been considerable discussion of and speculation concerning:
maintenance procedures at Lufthansa Technik, which has one of the very
highest reputations for maintenance quality; wiring, wiring conventions and
connectors in the A320 series; why the pilots did not discover the
discrepancy during the usual preflight control checks (the A320 displays
control surface displacement on the cockpit display, the ECAM, when the
sidestick is intentionally moved and the airplane is on the ground, as
during a preflight control system check). I think it is fair to say that few
hard facts have emerged yet concerning any of these, and I find it hard to
make any useful inferences about what actually went on from the publicly
available information.
What emerges most clearly so far from this incident is that the simple
physical complexity of the control system has confused some. Amongst other
things, explanations have been proposed by presumably technically
competent
people that do not fit the control system architecture. It is hard to see
how that phenomenon could have occurred with the simpler architectures of
mechanical control systems. On the other hand, the PNF was able to take over
normal control of the aircraft with one button push (the "control priority"
takeover on the sidestick), which could also not happen with the simpler
mechanical architectures.
We have very little information so far on the incident. It is certain that
the puzzles will be solved further along the investigative line, and very
likely that the results of the investigation will be highly significant for
the care and feeding of fly-by-wire architectures.
Peter Ladkin, University of Bielefeld, http://www.rvs.uni-bielefeld.de
[end quote]
From: "Peter B. Ladkin" <[email protected]>
Subject: A320 Incident
Tim van Beveren reported in *Flight International*, 22-28 May 2001, on a 20
Mar 2001 incident to a Lufthansa Airbus A320 on takeoff from Frankfurt.
This incident was reported at greater length and detail in *Air Safety
Week*, 4 Jun 2001, by David Evans and Tim van Beveren.
The captain was Pilot Flying (PF). there was some degree of turbulence
during takeoff, shortly after rotation, which resulted in the left wing
moving down. The captain applied correction (right lateral roll control) but
the wing dipped further left, reaching 21 degrees bank, and the wingtip is
reported to have come within half a meter of the ground, and according to
computer modelling of the digital flight data recorder the airplane "came
within a few seconds of striking the ground".
The First Officer, the pilot not flying (PNF), realising there could be a
control problem, switched "priority" to his sidestick controller and
recovered the aircraft. The aircraft was flown up to 12,000ft on autopilot,
the crew confirmed the problem, that the CAP's sidestick was controlling for
roll in the reverse sense (normally, putting the sidestick to the left
commands left roll; to the right commands right roll. Control-reversal here
means that CAP's sidestick gave right roll on a left movement and left roll
on a right movement).
The aircraft had just come out of maintenance. Maintenance is a known
risk -- James Reason, an authority on human factors in aviation safety and
Professor of Psychology at the University of Manchester, amongst others, has
detailed how significant problems may arise through maintenance of complex
systems.
It has happened many times that aircraft have come out of maintenance with
control systems reversed in one or more of the three axes (roll, pitch,
yaw). This has been the cause of a number of accidents with general aviation
aircraft, but my informal requests for information turned up no recent
accidents to commercial aircraft due to this cause. Evans and van Beveren
report that "reversed controls are deemed impossible on transport-category
aircraft" and that Boeing claims that the B737 aircraft cannot be
reverse-connected without it being discovered before flight, normally
through mandatory post-maintenance checks, but at the latest by the pilot's
preflight check, as the controls could not be moved.
At Lufthansa's code-sharing partner, United Air Lines, certified inspectors
must be stationed both inside and outside the cockpit to conduct a
functional check after the flight control system has been worked on; a
flight test is also required before the aircraft is returned to service
after this kind of repair. It is believed that either of these measures
would have caught the control-reversal problem, and so general
maintenance
procedures at Lufthansa Technik will be subject to detailed inquiry.
There have been a number of reports as to what fault caused the lateral
control reversal, including the two sources above. However, I have found
none of the explanations so far satisfactory, as they raise further puzzles
that they do not solve.
The following architectural description of the A320 primary flight control
system (PFCS) is drawn from Cary R. Spitzer, Digital Avionics Systems,
Second Edition, McGraw-Hill 1993. The A320 sidestick controller generates
input to five of the seven flight control computers which form part of the
primary flight control system (PFCS). These five are the two Elevator
Aileron Computers (ELACs) and the three Spoiler Elevator Computers (SECs).
Each wing has two outboard ailerons, and five inboard spoilers (overwing
surfaces which can be raised). Lateral (roll) control proceeds via four of
the five spoilers and the two ailerons. Each of the two ELACS and three SECs
control some combination of these 12 control surfaces. There is a
significant amount of control redundancy.
Initial reports said that Lufthansa Technik personnel had been repairing
one of the two ELACs, and had found a damaged pin on a connector. They
had replaced the connector and this had apparently caused the control
reversal. This explanation made no sense to me as it stood, because
(a) the connectors are standardised. Replacing one with another should
give exactly the same connections as were there before;
(b) if one ELAC was receiving reversed signals, and the other was not,
and the three SECs were not, then
(i) the PFCS architecture would detect a discrepancy on the channels, and
(ii) on each side, one aileron would operate counter to the other, but
all spoilers would operate correctly-sensed, and it is hard to see
how this could lead to the extreme control discrepancy reportedly
experienced by the PF.
The Aviation Safety Week report on June 4 suggested that "Repair work
involving complete rewiring "upstream" of the connector pins was conducted
over several work shifts". The ELAC connector with the damaged pin has 140
pins and is one of four such for the ELAC, for a total of 560 pins.
It seems to me that to get control reversal without the phenomena in (b)
above, there must have been a reversed signal downstream of the sidestick
but upstream of where the sidestick movement is multiplexed into the five
input signals to the five PFCS computers which receive them. I do not yet
have, nor have I heard, a coherent suggestion as to how that could occur.
There has been considerable discussion of and speculation concerning:
maintenance procedures at Lufthansa Technik, which has one of the very
highest reputations for maintenance quality; wiring, wiring conventions and
connectors in the A320 series; why the pilots did not discover the
discrepancy during the usual preflight control checks (the A320 displays
control surface displacement on the cockpit display, the ECAM, when the
sidestick is intentionally moved and the airplane is on the ground, as
during a preflight control system check). I think it is fair to say that few
hard facts have emerged yet concerning any of these, and I find it hard to
make any useful inferences about what actually went on from the publicly
available information.
What emerges most clearly so far from this incident is that the simple
physical complexity of the control system has confused some. Amongst other
things, explanations have been proposed by presumably technically
competent
people that do not fit the control system architecture. It is hard to see
how that phenomenon could have occurred with the simpler architectures of
mechanical control systems. On the other hand, the PNF was able to take over
normal control of the aircraft with one button push (the "control priority"
takeover on the sidestick), which could also not happen with the simpler
mechanical architectures.
We have very little information so far on the incident. It is certain that
the puzzles will be solved further along the investigative line, and very
likely that the results of the investigation will be highly significant for
the care and feeding of fly-by-wire architectures.
Peter Ladkin, University of Bielefeld, http://www.rvs.uni-bielefeld.de
[end quote]
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Is anybody seriously considering the routine of the PF control check? Many PNF checks of flight control operation on the flight control system page would not pick up incorrect sense. Many PNF say "checked" before surface indications return to neutral. This immediately invalidates the pilot flight control checks. Captains therefore have increased responsibility to ensure that controls are actually correctly checked.
I guess many FBW pilots are now meeting the new challenge. The question is of course, why not previously to this near fatal incident?
I guess many FBW pilots are now meeting the new challenge. The question is of course, why not previously to this near fatal incident?
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Peter
Small correction to your A320 explanation.
I'm sure you just forgot.
On each wing side there is just one aileron surface. This surface is controlled by 2 servo controls, one of which is active while the other is in damping mode. The 2 servos are never active at the same time.
FF
Small correction to your A320 explanation.
I'm sure you just forgot.
On each wing side there is just one aileron surface. This surface is controlled by 2 servo controls, one of which is active while the other is in damping mode. The 2 servos are never active at the same time.
FF
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We do all our flightcontrols checks PRIOR taxi (A319/A320/A321/A330). It has been mentioned several times, that the feedback of the travel direction is taken from the sidestick and not from the aileron itself. I don't agree, because if all the hydraulics are depressurized (engines not running), the aileron droop is visible on the FCTL ECAM page. With a centered stick, there would be no directional feedback.
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UPDATE
Hello everybody.
Has been some time that we have discussed this issue here and I just want to point your attention to the final report of the German Accident Investigation Board (BFU). An English language version is available at the BFU web page at
http://www.bfu-web.de/berichte/e_index.htm ,
file no 5X004-0/01 for download as a pdf file.
Everybody flying A3we should have a look into the "synopsis" and specially to the "contributing factors"
Happy landings
Tim van Beveren
(still independent) aviaton safety editor
Has been some time that we have discussed this issue here and I just want to point your attention to the final report of the German Accident Investigation Board (BFU). An English language version is available at the BFU web page at
http://www.bfu-web.de/berichte/e_index.htm ,
file no 5X004-0/01 for download as a pdf file.
Everybody flying A3we should have a look into the "synopsis" and specially to the "contributing factors"
Happy landings
Tim van Beveren
(still independent) aviaton safety editor
Last edited by TvB; 28th Feb 2004 at 23:02.
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I'm sorry to intrude here but...
Do pilots really bother to look out the window and check visually the control input results? How many of you DO look outside? Don't get me wrong here, but procedures made day after day after day, one day, will result on skipping some detail, out of simple trust on the system, because you know the system is too damn good.
Just my two cents...
GDL
Do pilots really bother to look out the window and check visually the control input results? How many of you DO look outside? Don't get me wrong here, but procedures made day after day after day, one day, will result on skipping some detail, out of simple trust on the system, because you know the system is too damn good.
Just my two cents...
GDL
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Amazing
I just realised that since I posted my update remark, the topic (which was dormant for almost two years) got more then 1.700 hits in less then 6 hrs. That's what I call traffic; - must be the headline though... 
Nevertheless, honestly: how many have been aware of this incident, its cause and implications?
Nevertheless, honestly: how many have been aware of this incident, its cause and implications?