Ueberlingen collision Trial started
Would an avionics question be pertinent here?
At our US company, the TCAS was out of service on the last leg, per MEL, on my last trip (a 100-seat turbofan). Only the normal, good old transponder mode C etc worked.
The MEL book had only one restriction, no PRM (parallel approaches, reduced lateral separation, radar monitored) approaches are allowed. No other limitations are required by the FAA. There was no mention of RVSM, altitude limitations (i.e. FL 290), autopilots etc.
It surprised both the First Officer and me that there were no other conditions, in order to operate 1,000' from aircraft at all altitudes. The RVSM is fairly new for us, and requires the digital altimeters and the large clean areas around static ports etc, but TCAS has been around many more years.
Does it seem like there is a contradiction here somewhere? Why would TCAS not be required to be operative, when we had no restrictions except for prohibiting PRM approaches?
This just now came back to me. One of our pilots who worked as a "Cruise FO" for two years with a 'north European' airline around '90-'91 was on our jumpseat about 14 years ago, going to ABQ. One dark night over eastern Russia the Captain went back to either sleep or puff on his pipe. This Cruise Pilot in the left seat was staring out ahead as they climbed to another altitude (before TCAS). "Kr****e" (his nickname over there) told me that he saw the lights of a large jet straight ahead on a collision course. He pushed the nose down a bit and missed the plane by not very much room! He told us something strange about ATC's response, when asked about the dangerous situation. Luckily they were in good VMC.
At our US company, the TCAS was out of service on the last leg, per MEL, on my last trip (a 100-seat turbofan). Only the normal, good old transponder mode C etc worked.
The MEL book had only one restriction, no PRM (parallel approaches, reduced lateral separation, radar monitored) approaches are allowed. No other limitations are required by the FAA. There was no mention of RVSM, altitude limitations (i.e. FL 290), autopilots etc.
It surprised both the First Officer and me that there were no other conditions, in order to operate 1,000' from aircraft at all altitudes. The RVSM is fairly new for us, and requires the digital altimeters and the large clean areas around static ports etc, but TCAS has been around many more years.
Does it seem like there is a contradiction here somewhere? Why would TCAS not be required to be operative, when we had no restrictions except for prohibiting PRM approaches?
This just now came back to me. One of our pilots who worked as a "Cruise FO" for two years with a 'north European' airline around '90-'91 was on our jumpseat about 14 years ago, going to ABQ. One dark night over eastern Russia the Captain went back to either sleep or puff on his pipe. This Cruise Pilot in the left seat was staring out ahead as they climbed to another altitude (before TCAS). "Kr****e" (his nickname over there) told me that he saw the lights of a large jet straight ahead on a collision course. He pushed the nose down a bit and missed the plane by not very much room! He told us something strange about ATC's response, when asked about the dangerous situation. Luckily they were in good VMC.
Last edited by Ignition Override; 3rd Jun 2007 at 04:16.
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As one of my colleagues so blantlantly put it...'if it werent for TCAS the accident woudnt happened
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It surprised both the First Officer and me that there were no other conditions, in order to operate 1,000' from aircraft at all altitudes. The RVSM is fairly new for us, and requires the digital altimeters and the large clean areas around static ports etc, but TCAS has been around many more years.
Does it seem like there is a contradiction here somewhere? Why would TCAS not be required to be operative, when we had no restrictions except for prohibiting PRM approaches?
Does it seem like there is a contradiction here somewhere? Why would TCAS not be required to be operative, when we had no restrictions except for prohibiting PRM approaches?
TCAS "caused" RVSM problems initially, since 2 aircraft 1000' apart, but slightly wobbling, would give off TAs - quite startling mid-Atlantic with an overtaker from behind
Now corrected in a software change...
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Skyguide - learning after Ueberlingen?
Interesting item in today's Tages Anzeiger.
http://www.tagesanzeiger.ch/dyn/news...ch/786287.html
To pre-empt complaints about "I can't read German", here a brief translation:
Skyguide apparently incapable of learning
Prior to the mid-air collision over Überlingen, Skyguide’s management had ignored all prior warnings by controllers. Are they now doing enough for safety? Doubts are justified.
Nobody can ever say that the mid-air collision at Überlingen on 1st July 2002 came out of the blue:
On 4th January 2002, air traffic controllers at Geneva write a letter to Skyguide management criticizing the practice at Zurich to allow partial control of air space by only one instead of two controllers. “The consequences are far too serious to be ignored”. On 6th March 2002, Skyguide boss Alain Rossier is the recipient of mail from the Zurich controllers’ association. “We are writing in the face of the desolate situation at Zurich ATC (…). Given the current personnel situation, we are unable to fulfil our mission (…). “ The letter goes on to describe a “Wild West” mentality, with everyone doing their job their own way. On 10th March 2002 a number of controllers warn the head of Zurich ATC, stating, “The daily situation is one of chaos”. Working conditions are said to be “unbearable”. And: “it is hard to imagine that we shall get through summer without trouble”.
Within four months, 71 passengers have to pay for the safety issues at Skyguide with their lives. At the time of the mid-air collision, only one controller is on duty – his colleague is on a break. After the crash, the Swiss civil aviation authority (Bazl) stops this practice and outlaws single man operations.
Prior to the Überlingen crash and even thereafter, a fatal pattern emerges: management implements changes without consultation of its operations staff – often in order to save costs. Some controllers voice concerns about safety implications. Management ignores them out of hand. Complaints are met with pressure tactics; people are discredited or even fired. Bazl only intervenes once matters become public – i.e. when it’s too late. This kind of safety culture may be fine for a shoe factory, but in ATC, even the slightest concerns have to be considered and risks eliminated. This is not happening at Skyguide, as demonstrated by the following four examples:
Example 1: Near Miss due to SMOP
On 13th December 2001, not one but two near misses occur within 90 seconds of each other in Zurich air space, a consequence of controller task saturation. The controller involved has been assigned his sector on the basis of SMOP (single man operation), as there is a shortage of controllers on that day. Despite internal criticism, Skyguide management adheres to this system – until Bazl outlaws it after the Überlingen mid-air collision. Skyguide even today justifies its practice, saying SMOP is a “generally accepted ATC practice” and in use in 14 countries, pointing out that Switzerland is one of only a few countries (if not the only one) where SMOP is prohibited in principle.
Example 2: Chaos with Eastern approaches
On 23rd October 2006, Zurich introduces ILS for Rwy 28. This allows Kloten Airport to be approached not only from the North and South, but also from the East under poor visibility. On 10th October 2006, 36 out of 61 controllers in a letter to management demand that this project be stopped for safety reasons. They raise concerns that the procedure has not been fully reviewed and will provoke dangerously close distances between aircraft to the extreme. Whilst global practice is to disentangle departures and approaches, Zurich is doing the opposite. The new procedure would not allow any controller even the slightest margin of lapse or error.
Management reacts by inviting the sceptical controllers to a meeting. By pure coincidence or not: at the same time, a new code of conduct is issued which lists all kinds of repercussions – right up to dismissal. Article 1 of the new code points out that an investigation may be initiated even for “unacceptable conduct causing disharmony within operations”. According to Skyguide, a meeting with Aerocontrol (the controller’s union) results in having demonstrated that “the concerns voiced in the letter have already been taken into consideration and procedures amended accordingly.” Subsequently, half of the signatories to the letter withdraw their concerns, the others quietly fume.
The position of Aerocontrol becomes more transparent in the days immediately leading up to the Überlingen trial. The union tells its members to shut up. “We wish to remind you that any contact with the media is prohibited (….) we prefer a coordinated strategy in dealing with the media, in which we have control over all statements”.
Example 3: Planning gone wrong and its consequences
Skyguide management plan to concentrate the upper sphere of Swiss air space at a new Upper Airspace Centre (UAC) in Geneva, enabling a reduction in personnel and consequential savings. In October 2004, controllers voice concerns, because 30 jobs are to be axed at Zurich before the new UAC is even opened. The controllers have little confidence in the new project on the one hand, and also believe that the job cuts in Zurich will have serious safety implications if the UAC project cannot be implemented as planned.
The protest by controllers has little effect on Skyguide’s management. However, an anonymous letter is sent to Federal Councillor Mortiz Leuenberger, whose portfolio includes civil aviation. The letter, sent in January 2006, points to “mismanagement and a continuous string of wrong decisions which cause grave concern to its authors”. The writing controllers criticize what they term a “cost intensive and useless exercise” and point to safety issues. “Skyguide cannot afford a second Überlingen”.
Indeed: two days before it is to go online, Bazl intervenes and pulls the plug on UAC, stating that the system is neither fail-safe nor properly tested. In addition, there appears to be any proof of proper training of controllers. In general, Skyguide is accused of awarding sufficient priority to safety. As a direct result of the collapse of the UAC project, there are now only 165 air traffic controllers at Zurich (instead of 206). This blatant shortage can only increase the risk of errors.
Example 4: Firings
Two of the authors of the letter of 10th March 2002 (“it is hard to imagine that we shall get through summer without trouble”) are women. As supervisors of assistant controllers they have often criticized shortcomings in safety and management, for instance in the context of the UAC and of non-adherence to duty rules.
In September 2005, one of the women receives the shocking news from her physician that she is suffering from leukaemia; six months later, Skyguide fires her after 27 years of service and excellent qualifications, citing that she had repeatedly acted without loyalty and against the interests of the Company. Her colleague is fired under the same pretext.
Both women go to court, and the verdict by the Bülach District Court (the same court with jurisdiction over the Überlingen mid-air collision case) is expected this autumn. Skyguide says that the two firings have to be seen against the background of “other issues, which we cannot make public for legal reasons.”
During the Überlingen trial, Prosecutor Bernhard Hecht tore into Skyguide for its “deficient awareness of risk” at management level and its “climate of carelessness” at operations level. Management clearly saw a greater priority in efficiency – read “profit” – than in safety. He called Skyguide’s management poor role models, being “careless, uncritical and uncommunicative.”
Skyguide, however, point out that Bazl are far stricter and more rigorous in any international comparison. In view of the number of aviation accidents in recent Swiss transport history this could be understood and seen as reasonable. But, says Skyguide, the logical consequence of this change in policy means, “that we have to find the common ground between us again”.
http://www.tagesanzeiger.ch/dyn/news...ch/786287.html
To pre-empt complaints about "I can't read German", here a brief translation:
Skyguide apparently incapable of learning
Prior to the mid-air collision over Überlingen, Skyguide’s management had ignored all prior warnings by controllers. Are they now doing enough for safety? Doubts are justified.
Nobody can ever say that the mid-air collision at Überlingen on 1st July 2002 came out of the blue:
On 4th January 2002, air traffic controllers at Geneva write a letter to Skyguide management criticizing the practice at Zurich to allow partial control of air space by only one instead of two controllers. “The consequences are far too serious to be ignored”. On 6th March 2002, Skyguide boss Alain Rossier is the recipient of mail from the Zurich controllers’ association. “We are writing in the face of the desolate situation at Zurich ATC (…). Given the current personnel situation, we are unable to fulfil our mission (…). “ The letter goes on to describe a “Wild West” mentality, with everyone doing their job their own way. On 10th March 2002 a number of controllers warn the head of Zurich ATC, stating, “The daily situation is one of chaos”. Working conditions are said to be “unbearable”. And: “it is hard to imagine that we shall get through summer without trouble”.
Within four months, 71 passengers have to pay for the safety issues at Skyguide with their lives. At the time of the mid-air collision, only one controller is on duty – his colleague is on a break. After the crash, the Swiss civil aviation authority (Bazl) stops this practice and outlaws single man operations.
Prior to the Überlingen crash and even thereafter, a fatal pattern emerges: management implements changes without consultation of its operations staff – often in order to save costs. Some controllers voice concerns about safety implications. Management ignores them out of hand. Complaints are met with pressure tactics; people are discredited or even fired. Bazl only intervenes once matters become public – i.e. when it’s too late. This kind of safety culture may be fine for a shoe factory, but in ATC, even the slightest concerns have to be considered and risks eliminated. This is not happening at Skyguide, as demonstrated by the following four examples:
Example 1: Near Miss due to SMOP
On 13th December 2001, not one but two near misses occur within 90 seconds of each other in Zurich air space, a consequence of controller task saturation. The controller involved has been assigned his sector on the basis of SMOP (single man operation), as there is a shortage of controllers on that day. Despite internal criticism, Skyguide management adheres to this system – until Bazl outlaws it after the Überlingen mid-air collision. Skyguide even today justifies its practice, saying SMOP is a “generally accepted ATC practice” and in use in 14 countries, pointing out that Switzerland is one of only a few countries (if not the only one) where SMOP is prohibited in principle.
Example 2: Chaos with Eastern approaches
On 23rd October 2006, Zurich introduces ILS for Rwy 28. This allows Kloten Airport to be approached not only from the North and South, but also from the East under poor visibility. On 10th October 2006, 36 out of 61 controllers in a letter to management demand that this project be stopped for safety reasons. They raise concerns that the procedure has not been fully reviewed and will provoke dangerously close distances between aircraft to the extreme. Whilst global practice is to disentangle departures and approaches, Zurich is doing the opposite. The new procedure would not allow any controller even the slightest margin of lapse or error.
Management reacts by inviting the sceptical controllers to a meeting. By pure coincidence or not: at the same time, a new code of conduct is issued which lists all kinds of repercussions – right up to dismissal. Article 1 of the new code points out that an investigation may be initiated even for “unacceptable conduct causing disharmony within operations”. According to Skyguide, a meeting with Aerocontrol (the controller’s union) results in having demonstrated that “the concerns voiced in the letter have already been taken into consideration and procedures amended accordingly.” Subsequently, half of the signatories to the letter withdraw their concerns, the others quietly fume.
The position of Aerocontrol becomes more transparent in the days immediately leading up to the Überlingen trial. The union tells its members to shut up. “We wish to remind you that any contact with the media is prohibited (….) we prefer a coordinated strategy in dealing with the media, in which we have control over all statements”.
Example 3: Planning gone wrong and its consequences
Skyguide management plan to concentrate the upper sphere of Swiss air space at a new Upper Airspace Centre (UAC) in Geneva, enabling a reduction in personnel and consequential savings. In October 2004, controllers voice concerns, because 30 jobs are to be axed at Zurich before the new UAC is even opened. The controllers have little confidence in the new project on the one hand, and also believe that the job cuts in Zurich will have serious safety implications if the UAC project cannot be implemented as planned.
The protest by controllers has little effect on Skyguide’s management. However, an anonymous letter is sent to Federal Councillor Mortiz Leuenberger, whose portfolio includes civil aviation. The letter, sent in January 2006, points to “mismanagement and a continuous string of wrong decisions which cause grave concern to its authors”. The writing controllers criticize what they term a “cost intensive and useless exercise” and point to safety issues. “Skyguide cannot afford a second Überlingen”.
Indeed: two days before it is to go online, Bazl intervenes and pulls the plug on UAC, stating that the system is neither fail-safe nor properly tested. In addition, there appears to be any proof of proper training of controllers. In general, Skyguide is accused of awarding sufficient priority to safety. As a direct result of the collapse of the UAC project, there are now only 165 air traffic controllers at Zurich (instead of 206). This blatant shortage can only increase the risk of errors.
Example 4: Firings
Two of the authors of the letter of 10th March 2002 (“it is hard to imagine that we shall get through summer without trouble”) are women. As supervisors of assistant controllers they have often criticized shortcomings in safety and management, for instance in the context of the UAC and of non-adherence to duty rules.
In September 2005, one of the women receives the shocking news from her physician that she is suffering from leukaemia; six months later, Skyguide fires her after 27 years of service and excellent qualifications, citing that she had repeatedly acted without loyalty and against the interests of the Company. Her colleague is fired under the same pretext.
Both women go to court, and the verdict by the Bülach District Court (the same court with jurisdiction over the Überlingen mid-air collision case) is expected this autumn. Skyguide says that the two firings have to be seen against the background of “other issues, which we cannot make public for legal reasons.”
During the Überlingen trial, Prosecutor Bernhard Hecht tore into Skyguide for its “deficient awareness of risk” at management level and its “climate of carelessness” at operations level. Management clearly saw a greater priority in efficiency – read “profit” – than in safety. He called Skyguide’s management poor role models, being “careless, uncritical and uncommunicative.”
Skyguide, however, point out that Bazl are far stricter and more rigorous in any international comparison. In view of the number of aviation accidents in recent Swiss transport history this could be understood and seen as reasonable. But, says Skyguide, the logical consequence of this change in policy means, “that we have to find the common ground between us again”.
Pegase Driver
Thread Starter
Nothing new in this article , but one can can only wonder as to why this article appears only 3 days before the verdict of the Ueberlingen trial is going to be made public...
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There is nothing such as a Collision Avoidance System betwenn Newsmen and Judges. But, knowing the judicial system in Switzerland, you can rely on that its decision won't be influenced by a press report. Remains the public: so far, it didn't really took into account SkyGuide mismanagement before getting to the airport... 
'nough said
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4 ATC managers have been convicted according to the BBC newsflash I just saw. No more info at present.
Last edited by amanoffewwords; 4th Sep 2007 at 15:37. Reason: corrected job titles
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Awaiting the details , but the TSR ( swiss news agency ) reported 4 of the 8 condemned , 4 others acquitted.
The 4 condemned are reported to be 3 management staff each received 12 months jail suspended sentences and the maintenance chief is condemned to 90 days-fine of 150 CHF each ( Swiss fine system ).
More later
The 4 condemned are reported to be 3 management staff each received 12 months jail suspended sentences and the maintenance chief is condemned to 90 days-fine of 150 CHF each ( Swiss fine system ).
More later
Ecce Homo! Loquitur...
BBC: Four guilty over Swiss air crash
A Swiss court has found four employees of an air traffic control firm guilty of manslaughter over the deaths of 71 people in a mid-air collision in 2002.
Three of the four managers convicted were given suspended prison terms and the fourth was ordered to pay a fine. Another four employees of the Skyguide firm were cleared of any wrongdoing.
Prosecutors had said a "culture of negligence" at the firm contributed to the mid-air collision, which killed mostly Russian children.
A Swiss court has found four employees of an air traffic control firm guilty of manslaughter over the deaths of 71 people in a mid-air collision in 2002.
Three of the four managers convicted were given suspended prison terms and the fourth was ordered to pay a fine. Another four employees of the Skyguide firm were cleared of any wrongdoing.
Prosecutors had said a "culture of negligence" at the firm contributed to the mid-air collision, which killed mostly Russian children.
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The BBC should correct thier news flash.
The flash says (as of 3:45GMT) "4 ATC Controllers convicted..." but the story clearly states that they were actually management staff.
The flash says (as of 3:45GMT) "4 ATC Controllers convicted..." but the story clearly states that they were actually management staff.
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As I recall, the part of the system that warns the controller if two ac are on a collision track where not operational this terrible night. and because of that two controllers instead of one where on duty
I was wandering if some controllers used this part of the system as a reminder for them selves of when to issue a climb or descent order to ac.
If that is the case it increases the risk of forgetting to take action if the controller is used to act on the "warning."
I was wandering if some controllers used this part of the system as a reminder for them selves of when to issue a climb or descent order to ac.
If that is the case it increases the risk of forgetting to take action if the controller is used to act on the "warning."
Ecce Homo! Loquitur...
Additions to the BBC report:
............All eight men on trial had maintained their innocence. Seven had continued working for Skyguide until the time of the verdict.
The BBC's Imogen Foulkes, in Berne, says it is significant that the four Skyguide employees acquitted were all air traffic controllers - rather than managers. She says this shows the judges backed the prosecution's view that the managers at Skyguide were responsible for introducing negligent, potentially dangerous working practices.
Two separate investigations have already found what were described as organisational deficiencies within Skyguide. These deficiencies were said to have contributed to the accident........
............All eight men on trial had maintained their innocence. Seven had continued working for Skyguide until the time of the verdict.
The BBC's Imogen Foulkes, in Berne, says it is significant that the four Skyguide employees acquitted were all air traffic controllers - rather than managers. She says this shows the judges backed the prosecution's view that the managers at Skyguide were responsible for introducing negligent, potentially dangerous working practices.
Two separate investigations have already found what were described as organisational deficiencies within Skyguide. These deficiencies were said to have contributed to the accident........
As I recall, the part of the system that warns the controller if two ac are on a collision track where not operational this terrible night. and because of that two controllers instead of one where on duty
I was wandering if some controllers used this part of the system as a reminder for them selves of when to issue a climb or descent order to ac
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When reading the article at CNN.com at the end they state;
Rather debateble. Not the fact that it was wrong. But that it indeed was a mistake fully by the controller.
He also mistakenly told the Russian plane to descend -- sending it straight into the cargo jet.
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For Ppruners mastering German the following link gives a comprehensive report of the trial and the verdict:
http://www.nzz.ch/2005/10/30/il/articleD9VFI.html
Main points:
The one-man operation as applied in Zurich is not in accordance with safety requirements in Air Traffic Services. The organisation of ATC requires a backup for human failure.
Three managers, between 50 and 61 of age, one of them being the former manager of ATC Zurich, were found guilty for negligent behaviour resulting in the death of people and sentenced to 12 months suspended.
The Swiss one-man operation had been contested previous to the collision and had been suspended in Genève. In Zurich nothing had been changed despite repeated criticism, which the court noted as "industrial blindness".
The lack of information about the maintenance of communication lines was blamed to the project leader, who was on leave at the time of the collision but had failed to inform the adjacent centres; The 64 years old pensioned project leader was sentenced to a fine of 13.500 Swiss Franks. The technician on duty at the night of the collision was acquitted.
Also acquitted was a supervisor, a system manager and the controller who had taken a rest. The latter was acquitted thanks to a juridical contradiction. On the one hand he was charged to be negligent in obtaining information about his watch but on the other hand he had taken his rest despite this knowledge and in agreement with his (murdered) colleague.
Skyguide is discussing with their convicted staff whether to lodge an appeal. Two of the convicted staff are still employed, but not in their original function. The court called the convicted staff members to accept their conviction in the interest of all parties involved.
http://www.nzz.ch/2005/10/30/il/articleD9VFI.html
Main points:
The one-man operation as applied in Zurich is not in accordance with safety requirements in Air Traffic Services. The organisation of ATC requires a backup for human failure.
Three managers, between 50 and 61 of age, one of them being the former manager of ATC Zurich, were found guilty for negligent behaviour resulting in the death of people and sentenced to 12 months suspended.
The Swiss one-man operation had been contested previous to the collision and had been suspended in Genève. In Zurich nothing had been changed despite repeated criticism, which the court noted as "industrial blindness".
The lack of information about the maintenance of communication lines was blamed to the project leader, who was on leave at the time of the collision but had failed to inform the adjacent centres; The 64 years old pensioned project leader was sentenced to a fine of 13.500 Swiss Franks. The technician on duty at the night of the collision was acquitted.
Also acquitted was a supervisor, a system manager and the controller who had taken a rest. The latter was acquitted thanks to a juridical contradiction. On the one hand he was charged to be negligent in obtaining information about his watch but on the other hand he had taken his rest despite this knowledge and in agreement with his (murdered) colleague.
Skyguide is discussing with their convicted staff whether to lodge an appeal. Two of the convicted staff are still employed, but not in their original function. The court called the convicted staff members to accept their conviction in the interest of all parties involved.
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Originally Posted by KiloKilo
CNN:
He also mistakenly told the Russian plane to descend -- sending it straight into the cargo jet.
He also mistakenly told the Russian plane to descend -- sending it straight into the cargo jet.
Giving an aircraft in a conflict situation a clearance which will resolve that situation is absolutely the right thing to do. The only procedural exception is when the controller *knows* that an aircraft is operating under an ACAS RA, in which case heshe is to issue at most informational advisories only.
(It should be clear that I am not going to follow ATC Watcher's plea not to re-open the discussion of the accident. I beg forgiveness. From the comments so far, it seems to me that there is certain information about TCAS that has not made it out into the wider pilot community and I think it might be opportune to point to it here.)
Nielsen was not advised of the RA until some half-minute into the situation, because DHL's FO was in the loo and the CAP was concentrating on his flight duties.
Nielsen undertook two actions which one can characterise as mistaken. One was allowing the loss of required horizontal separation. The other was in reporting the conflicting traffic to Bakshirian at 2 o'clock when the traffic was actually at 10 o'clock and in sight. (I am not going to address here the causes of these actions. These have been well laid out elsewhere.)
This latter turned out to be crucial. As I speculated in a WWW-available paper a month after the collision, and which was confirmed by the report, this led the Bakshirian crew to think they were in a three-aircraft conflict situation: themselves, traffic at 10 o'clock in sight, and further traffic at 2 o'clock that they didn't see. As I argued in my paper
in the 2004 Safety-Critical Systems and Software conference in Australia, available at
crpit.com/Vol47.html
alternatively at
http://http://www.rvs.uni-bielefeld.de/publications/Reports/SCSS04.pdf
this presented Bakshirian with a decision situation in which it was rational for them to choose to descend.
There are two crucial observations which follow from this, which have unfortunately been lost in the ensuing chatter.
1. Despite the "TCAS philosophy" which says that
TCAS activates when aircraft have violated separation; andtherefore when ATC has already failed; and therefore ATC is "out of the reckoning",
it is still possible for ATC to give legitimate input which will causally influence the outcome of an avoidance manoeuvre. In other words, the "TCAS philosophy" is based on a mistake.
When I say "legitimate", this does not mean "non-mistaken". People do make mistakes; indeed, the cognitive mistake made by Nielsen in his statement is common ("2 o'clock" is the participant-reciprocal of "10 o'clock). A system design which relies for its efficacy on operator actions, and TCAS is such, must explicitly take into account such common forms of human error.
2. One might also think that, had Nielsen known of the RA sooner, the outcome would have been avoided. Not necessarily so: it would have been within ICAO guidelines for Nielsen to have said "Bakshirian, advise intruder at your 2 o'clock" even if he knew of the RA, thus putting the Russians in exactly the same decision situation as they had in the actual scenario.
It is well known that a two-aircraft resolution algorithm such as employed by TCAS cannot resolve all conflicts. However, it is not even known whether the algorithm can even resolve all *three-aircraft* conflicts. (Is it known through work of Nancy Lynch and colleagues at MIT that it can resolve all two-aircraft conflicts.) Since 2002, I have offered a PhD to anyone who can either show that the TCAS algorithm mathematically resolves all three-aircraft conflicts, or alternatively produce a three-aircraft scenario which it cannot resolve (I have reduced the choice of such a scenario to a limited set of cases). Five years later, no one has successfully taken up that challenge. It stands; I issue it again here.
I cannot think it wise to advise people to *always, without exception* follow an RA, when we don't even know that the algorithm is correct (that is, correctly resolves all cases that concern us, such as three-aircraft conflicts), unless a risk analysis has been performed to show that the exceptions are expected to occur in only a negligible number of cases. To my knowledge, no such analysis has ever been performed.
I think it even less wise to suggest *mandating* the following of an RA, as the BFU issued as a safety recommendation. Forcing people to follow an algorithm which you can't show is correct is not something which sits well with modern ideas of society and choice. (BTW, I don't know that the BFU was aware of the issues I mention here at the time they issued their recommendation. But they could have been: I put the info on the WWW in August 2002.)
PBL
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Out of the box
(30 years since I was at Leeming as an air ftaffic control assistant) .
It is always tragic that people fix on a course of action and die but surely a simple solution would have been if both aircraft had turned left even for a few seconds then they would have each headed away from the other? The problem was surely they were both heading for the same piece of airspace and they needed to just not do that. A few seconds then back onto their headings with danger passed? Tell me why they couldnt have done that ? Isnt the decision to focus on the decent or climb rather than change heading the key factor here?
It is always tragic that people fix on a course of action and die but surely a simple solution would have been if both aircraft had turned left even for a few seconds then they would have each headed away from the other? The problem was surely they were both heading for the same piece of airspace and they needed to just not do that. A few seconds then back onto their headings with danger passed? Tell me why they couldnt have done that ? Isnt the decision to focus on the decent or climb rather than change heading the key factor here?
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And for French reading Ppruners I recommend: http://www.letemps.ch/template/regio...article=214204
This article in the Geneva based 'Le Temps' is even more outspoken than the German language paper of Zurich cited in my previous message.
In an editorial it is commented that an entire industrial culture has been sanctioned. For years on end Skyguide Directors had tolerated that a single controller handled the traffic, while only on paper a second one was attributed who was in fact paid for taking his rest in another room. The responsible managers had forgotten that safety is all about taking account of the unforseen and the possibility of human error.
That is the reason why the managers in their offices now foot the bill by getting severe punishment. Whereas THE FRONT-LINE EMPLOYEES HAVE QUITE CLEARLY BEEN DISCHARGED. The president of the tribunal has taken the occasion to REHABILITATE THE LATE DANISH CONTROLLER ON DUTY on the night of the tragedy, whereas his colleagues had the delicacy of putting all the blame on him.
Although the verdict is against individuals, Skyguide as an enterprise is at stake. The woolly reaction on the verdict by Skyguide will not improve anything. Their new director will have a job in restoring confidence.
So far the commentary of this newspaper, confirming that our colleague Peter Nielsen has been rehabilitated. The confidence in Skyguide as an organisation may be low, my confidence in the Swiss courts is very, very high.
Songbird
This article in the Geneva based 'Le Temps' is even more outspoken than the German language paper of Zurich cited in my previous message.
In an editorial it is commented that an entire industrial culture has been sanctioned. For years on end Skyguide Directors had tolerated that a single controller handled the traffic, while only on paper a second one was attributed who was in fact paid for taking his rest in another room. The responsible managers had forgotten that safety is all about taking account of the unforseen and the possibility of human error.
That is the reason why the managers in their offices now foot the bill by getting severe punishment. Whereas THE FRONT-LINE EMPLOYEES HAVE QUITE CLEARLY BEEN DISCHARGED. The president of the tribunal has taken the occasion to REHABILITATE THE LATE DANISH CONTROLLER ON DUTY on the night of the tragedy, whereas his colleagues had the delicacy of putting all the blame on him.
Although the verdict is against individuals, Skyguide as an enterprise is at stake. The woolly reaction on the verdict by Skyguide will not improve anything. Their new director will have a job in restoring confidence.
So far the commentary of this newspaper, confirming that our colleague Peter Nielsen has been rehabilitated. The confidence in Skyguide as an organisation may be low, my confidence in the Swiss courts is very, very high.
Songbird