TCAS philosophies
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Originally Posted by punkalouver
I direct you to the Eurocontrol ACAS Bulletin #9 and quote...
" 5. The factor of collision risk reduction thanks to TCAS II in the operational world, taking into account some non TCAS II equipped aircraft, inaccurate pilot responses and lack of responses, altitude reporting inaccuracies, etc."
" 5. The factor of collision risk reduction thanks to TCAS II in the operational world, taking into account some non TCAS II equipped aircraft, inaccurate pilot responses and lack of responses, altitude reporting inaccuracies, etc."
And I'm sure they arrived at this figure by finding out that there were 80% fewer mid-air collisions since the mandatory introduction of ACAS-II per billion flight hours, compared to before. Or did they?
Otherwise, this figure is completely bogus. (I'm certain it is bogus anyway, since luckily the number of mid-air collisions is too low to derive any statistical significance from it.)
There have been some irresponsible statements made much earlier in this thread. It is rational to Follow The RA even if it contradicts an ATC instruction.
Bernd
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Originally posted by bsieker
And I'm sure they arrived at this figure by finding out that there were 80% fewer mid-air collisions since the mandatory introduction of ACAS-II per billion flight hours, compared to before. Or did they?
And I'm sure they arrived at this figure by finding out that there were 80% fewer mid-air collisions since the mandatory introduction of ACAS-II per billion flight hours, compared to before. Or did they?
I don't have the details of how they came to their conclusion or Joernstu came to his conclusion, but I am left with a choice of believing an organization called Eurocontrol and their statements and excellent newsletter or the supposed risk evaluation of some guy on a website called Joernstu.
Choice made. I believe the collision risk is less with TCAS installed.
Interesting that they underlined "operational world" in their statement. Maybe they are reading this thread. Perhaps this "risk evaluation of would be episodes" should be sent to them and they can reply with their "bogus" data as you call it. After all, safety is our common goal.
Last edited by punkalouver; 9th Dec 2007 at 23:54.
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It is rational to Follow The RA even if it contradicts an ATC instruction.
Problem is, as soon as you introduce humans into your system, the question of rationality becomes a lot wider. A course taken by a human will be rational, if he acts acording to the limited information he has. If he chooses, the best way for him to solve his problem will be course A, course A will be a rational choice. You cannot decide on the rationality of a humans actions by looking at the outcome alone - the pilot's cristal ball isn't near as good enough for this ;-)
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Well thank you, I'm glad you agree with me. After all it was a statement(way back in the thread) that contradicting the RA was a rational choice that got me involved in this thread.
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Well thank you, I'm glad you agree with me. After all it was a statement(way back in the thread) that contradicting the RA was a rational choice that got me involved in this thread.
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Originally Posted by punkalouver
After all it was a statement(way back in the thread) that contradicting the RA was a rational choice that got me involved in this thread.
PBL
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I'd say Eurocontrol and I are on the same wavelength about how to proceed in such a situation. The BFU as well. I take them seriously and don't refer to statements from them or one of them as bogus. It is not for the TCAS experts to take me seriously. It is me taking them seriously which I do.
Why don't you send this problem or situation to the appropriate Eurocontrol department(we already know the BFU's opinion) and we can see what their reply is. I will start holding my breath now.
Why don't you send this problem or situation to the appropriate Eurocontrol department(we already know the BFU's opinion) and we can see what their reply is. I will start holding my breath now.
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Originally Posted by punkalouver
I'd say Eurocontrol and I are on the same wavelength about how to proceed in such a situation. The BFU as well.
As far as I know, the colleagues at Eurocontrol were reading this thread when there was technical discussion (I doubt they are bothering any more, and I can't be bothered to ask).
The BFU has nobody expert in safety-critical digital systems,
and why should they. They don't design them, build them or analyse them.
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Hmm, so now I am youthful and inexperienced by reading Eurocontrol newsletters that say to FOLLOW THE RA, ageeing with them and feeling we are on the same wavelength. As well, the BFU in their final report recommends "never manouver in the opposite sense to an RA(directly from the report that deals with your scenario). I am youthfully on the same wavelength with them despite my inexperience.
I thought about your scenario the other day as I was flying along at a high altitude. There was 180° opposite traffic almost on our track that we knew was several thousand feet below us. We saw their contrail well before we crossed paths. For much of the time their contrail appeared above us. It was definitely above the horizon until it got much closer and became obvious that it was much below us. Sort of like the cloud tops that often appear to be at our level initially the pass by down below. Your scenario has the option to visually manouver to avoid the visually aquired traffic which is opposite to the RA that has alerted you to a strong collision potential. As I have previously said, visual illusions, especially at night can make it extremely difficult to accurately assess the trajectory of another aircraft in this situation.
In your scenario, which is the accident scenario, it is safer to climb. Why, because we know how extremely dangerous it is to descend as proven by the European collision and other near collisions and it is unlikely that the TCAS is wrong. The other guy will likely be descending as well because he is well trained. Manouvering visually may make things worse in many cases (especially at high speeds, high altitude and night). How easy is it to manouver visually around a rotating beacon and a set of nav lights closing in at 500 miles per hour, possibly against a backgound of many ground lights). Is this your actual experience and non-youthfulness speaking on how easy it would have been for the 154 to descend and visually manouver around the 757).
How dangerous is it to climb or maintain level flight(assuming that there really is an aircraft out there that you can't see)? I don't know, but I say less dangerous. Why? The big sky theory. The chances of actually hitting that aircraft are still extremely small. ATC is going to calling for an immediate climb or descent if your aircaft will be within 5 miles of each other(or whatever the minimum separation is). TCAS is calling for a manouver when the collision potential is much higher. It is nice to have hours upon end in an office to analyze various scenarios. When you have few seconds to make your decision, certain procedures should already be clear in your mind. Sure, there is always the obscure scenario where acting contrary to the SOP saves the day. But that is a rare day. and it wasn't the Day(or night) over Germany.
That the BFU has no experts on TCAS is not surprising. Safety boards typically bring in outside experts during an investigation.
It is unfortunate to hear that you are close enough to Eurocontrol to be
aware that they were reading this thread yet you "can't be bothered" to attempt to discuss with them your scenario and their recommendations and reasons for their recommendations for your scenario.
In case you happen to find the time, their address, fax and phone number are on their newsletter.
I thought about your scenario the other day as I was flying along at a high altitude. There was 180° opposite traffic almost on our track that we knew was several thousand feet below us. We saw their contrail well before we crossed paths. For much of the time their contrail appeared above us. It was definitely above the horizon until it got much closer and became obvious that it was much below us. Sort of like the cloud tops that often appear to be at our level initially the pass by down below. Your scenario has the option to visually manouver to avoid the visually aquired traffic which is opposite to the RA that has alerted you to a strong collision potential. As I have previously said, visual illusions, especially at night can make it extremely difficult to accurately assess the trajectory of another aircraft in this situation.
In your scenario, which is the accident scenario, it is safer to climb. Why, because we know how extremely dangerous it is to descend as proven by the European collision and other near collisions and it is unlikely that the TCAS is wrong. The other guy will likely be descending as well because he is well trained. Manouvering visually may make things worse in many cases (especially at high speeds, high altitude and night). How easy is it to manouver visually around a rotating beacon and a set of nav lights closing in at 500 miles per hour, possibly against a backgound of many ground lights). Is this your actual experience and non-youthfulness speaking on how easy it would have been for the 154 to descend and visually manouver around the 757).
How dangerous is it to climb or maintain level flight(assuming that there really is an aircraft out there that you can't see)? I don't know, but I say less dangerous. Why? The big sky theory. The chances of actually hitting that aircraft are still extremely small. ATC is going to calling for an immediate climb or descent if your aircaft will be within 5 miles of each other(or whatever the minimum separation is). TCAS is calling for a manouver when the collision potential is much higher. It is nice to have hours upon end in an office to analyze various scenarios. When you have few seconds to make your decision, certain procedures should already be clear in your mind. Sure, there is always the obscure scenario where acting contrary to the SOP saves the day. But that is a rare day. and it wasn't the Day(or night) over Germany.
That the BFU has no experts on TCAS is not surprising. Safety boards typically bring in outside experts during an investigation.
It is unfortunate to hear that you are close enough to Eurocontrol to be
aware that they were reading this thread yet you "can't be bothered" to attempt to discuss with them your scenario and their recommendations and reasons for their recommendations for your scenario.
In case you happen to find the time, their address, fax and phone number are on their newsletter.
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punkalouver, in all your argumentation, you continously overlook, that the topic of this threat is the discussion on TCAS philosophies. This cannot be limited to the teaching material published by any organisation.
I wonder - if you really have read the Eurocontrol bulletins as you said you have, why hasn't it occured to you, that all the cases published there have one causal factor in common: TCAS. Some of the problems described are related to training, but some of them seem to be very hard to mitigate, e.g. the interception of a A340 by a military jet transmitting altitude information described in Bulletin 9. Apart from changing the practice by the airforce there seems to be little, that can prevent this kind of incident from happening. What strikes me in this incident is, that only the disregard of the A340 crew to follow the TCAS RA when reaching critical altitude led to a reversal RA. TCAS could have noticed that the intruder (airforce) was not acting according to the TCAS logic and could have issued a reversal earlier - but this will be solved in TCAS 7.1 as Eurocontrol promised.
Interestingly enough, you quote the BFU report but seem not to recognise, that the first point stated by the BFU report under "systematic causes" (page 119 in the german version) is the insufficient integration of TCAS into the aviation system.
I wonder - if you really have read the Eurocontrol bulletins as you said you have, why hasn't it occured to you, that all the cases published there have one causal factor in common: TCAS. Some of the problems described are related to training, but some of them seem to be very hard to mitigate, e.g. the interception of a A340 by a military jet transmitting altitude information described in Bulletin 9. Apart from changing the practice by the airforce there seems to be little, that can prevent this kind of incident from happening. What strikes me in this incident is, that only the disregard of the A340 crew to follow the TCAS RA when reaching critical altitude led to a reversal RA. TCAS could have noticed that the intruder (airforce) was not acting according to the TCAS logic and could have issued a reversal earlier - but this will be solved in TCAS 7.1 as Eurocontrol promised.
Interestingly enough, you quote the BFU report but seem not to recognise, that the first point stated by the BFU report under "systematic causes" (page 119 in the german version) is the insufficient integration of TCAS into the aviation system.
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Originally posted by joernstu
punkalouver, in all your argumentation, you continously overlook, that the topic of this threat is the discussion on TCAS philosophies. This cannot be limited to the teaching material published by any organisation.
punkalouver, in all your argumentation, you continously overlook, that the topic of this threat is the discussion on TCAS philosophies. This cannot be limited to the teaching material published by any organisation.
1) that the actions of the TU-154 crew were rational
2)The statement "I cannot decide, what kind of action would induce the lowest risk - following an RA, not following an RA or flying without TCAS at all as the basis for my risk evaluation would be episodes. I think the same goes for you as your information basis is still only episodes."
There are occasional pilots out there who will read or hear about about some obscure or one-off scenario(not necessarily TCAS related) and as a result decide that they have a better plan of action than the SOP. Perhaps it is how to deal with a certain type of fire or ditching procedure. I have flown with these types. Statements like your coming from a supposed accident analysis panel or whatever it is called I believe increases the likelyhood of some people disregarding or going against an RA.
Originally posted by joernstu
I wonder - if you really have read the Eurocontrol bulletins as you said you have, why hasn't it occured to you, that all the cases published there have one causal factor in common: TCAS.
I wonder - if you really have read the Eurocontrol bulletins as you said you have, why hasn't it occured to you, that all the cases published there have one causal factor in common: TCAS.
Originally posted by joernstu
Interestingly enough, you quote the BFU report but seem not to recognise, that the first point stated by the BFU report under "systematic causes" (page 119 in the german version) is the insufficient integration of TCAS into the aviation system.
Interestingly enough, you quote the BFU report but seem not to recognise, that the first point stated by the BFU report under "systematic causes" (page 119 in the german version) is the insufficient integration of TCAS into the aviation system.
So the training and regulations were not proper or were contradictory. This could lead to problems in many areas. I believe the BFU is correct. This is a regulatory issue which I believe has been corrected.
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Young man, this is getting really tedious. Let me try to put another perspective on things.
You introduce the notion of responsibility. This is not a foreign notion to engineers, but part of most of the codes of conduct of most professional engineering societies.
The engineering facts which you choose not to like, inter alia that, given the decision presented to the Tu-154 crew, it would have been rational for them to choose to go against the TCAS RA, were discovered, as far as I can tell, by me, and have been published in an engineering organ after peer review by two published TCAS experts, one a Fellow of the Royal Aeronautical Society who liked the paper, and one by an engineer for a major ANSP, who did not like what he read but was unable to construct any valid counterarguments.
It is in the code of conduct of many professional engineering societies that if one becomes aware of significant safety issues with engineered systems, one is obliged to make these issues known at least to the profession and to users of these systems. This obligation falls under the concept of "professional responsibility".
I did that, and continue to do so.
Instead, you suggest this very action is "irresponsible". That is a perjorative term. Were you to be a professional engineer and a member of a professional engineering organisation, you would be censured by that organisation for saying such things publically. For most societies censure the public defaming of work of fellow engineering professionals.
Defaming is or course different from technical criticism, which is generally encouraged. But you have been repeatedly asked over almost six months for arguments contravening the engineering fact that you do not like, and you have repeatedly evaded the question. While repeating your defamation.
If you pretend to be a professional, the only way you can get away with that behavior without censure is that this is an anonymous forum and nobody knows who you are. I think that it in general a good thing, because there are all sorts of facts that people don't like and which they attempt to suppress, and it is good to have a place in which they can be brought up and discussed without political consequences. But by the same token I don't think the forum should be used to propagate abuse.
So I'll just ask you to behave like a professional. If you are not sure what that involves, let me suggest you check out a few codes of conduct of engineering societies which are available on the WWW.
PBL
Originally Posted by punkalouver
I have just responded and perhaps added to 2 very, in my opinion, irresponsible statements.
1) that the actions of the TU-154 crew were rational
1) that the actions of the TU-154 crew were rational
The engineering facts which you choose not to like, inter alia that, given the decision presented to the Tu-154 crew, it would have been rational for them to choose to go against the TCAS RA, were discovered, as far as I can tell, by me, and have been published in an engineering organ after peer review by two published TCAS experts, one a Fellow of the Royal Aeronautical Society who liked the paper, and one by an engineer for a major ANSP, who did not like what he read but was unable to construct any valid counterarguments.
It is in the code of conduct of many professional engineering societies that if one becomes aware of significant safety issues with engineered systems, one is obliged to make these issues known at least to the profession and to users of these systems. This obligation falls under the concept of "professional responsibility".
I did that, and continue to do so.
Instead, you suggest this very action is "irresponsible". That is a perjorative term. Were you to be a professional engineer and a member of a professional engineering organisation, you would be censured by that organisation for saying such things publically. For most societies censure the public defaming of work of fellow engineering professionals.
Defaming is or course different from technical criticism, which is generally encouraged. But you have been repeatedly asked over almost six months for arguments contravening the engineering fact that you do not like, and you have repeatedly evaded the question. While repeating your defamation.
If you pretend to be a professional, the only way you can get away with that behavior without censure is that this is an anonymous forum and nobody knows who you are. I think that it in general a good thing, because there are all sorts of facts that people don't like and which they attempt to suppress, and it is good to have a place in which they can be brought up and discussed without political consequences. But by the same token I don't think the forum should be used to propagate abuse.
So I'll just ask you to behave like a professional. If you are not sure what that involves, let me suggest you check out a few codes of conduct of engineering societies which are available on the WWW.
PBL
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All I can say in response to the last post is to suggest that anyone(preferably people not associated with myself or PBL) who is interested in this back and forth posting, to read what I have printed and post what they think I have said here is unprofessional.
I don't disagree or necessarily know what what engineering facts you have discovered. There are no facts on this thread or any of your studies that I have ever said I don't like. I assume they are correct.
I strongly disagree with the two posts that I previously mentioned and stand by them. I don't have technical studies to throw into the forum to back up my arguements. All I have is real world results to look at. Publications giving example after example of saves by TCAS, near collisions caused by improper procedures regarding TCAS and near and actual collisions caused by ignoring TCAS. Then of course there is the occasional TCAS related incident.
As for the not responding for six months, I have no technical engineering or studies to give mathematical probabilities of how much safer it is to follow the RA in the midair collision incident. Just real world actions and opinions.
Perhaps you could respond on how to visually avoid that 757(probably seen only as dim lights) closing in at 1000 km/h or more, probably descending as well, and quite possibly against a background of lights. There are no mathematical formulas for this and theory and statistics don't work in a split decision moment like this. Perhaps blind luck does.
Now new terms have been brought in.
Defamation. Which rightly or wrongly makes me think lawsuit in my part of the world and makes me glad for anonymity.
abuse. Please, contact the moderator and ask him to review this thread and give an opinion on what abuse I have given out on this thread and please publish the response. There has been no abuse here. I know there will be no follow up on this one.
Maybe its time to lighten up with this enlightening link.
http://www.successunlimited.co.uk/humour/engineer.htm
I don't disagree or necessarily know what what engineering facts you have discovered. There are no facts on this thread or any of your studies that I have ever said I don't like. I assume they are correct.
I strongly disagree with the two posts that I previously mentioned and stand by them. I don't have technical studies to throw into the forum to back up my arguements. All I have is real world results to look at. Publications giving example after example of saves by TCAS, near collisions caused by improper procedures regarding TCAS and near and actual collisions caused by ignoring TCAS. Then of course there is the occasional TCAS related incident.
As for the not responding for six months, I have no technical engineering or studies to give mathematical probabilities of how much safer it is to follow the RA in the midair collision incident. Just real world actions and opinions.
Perhaps you could respond on how to visually avoid that 757(probably seen only as dim lights) closing in at 1000 km/h or more, probably descending as well, and quite possibly against a background of lights. There are no mathematical formulas for this and theory and statistics don't work in a split decision moment like this. Perhaps blind luck does.
Now new terms have been brought in.
Defamation. Which rightly or wrongly makes me think lawsuit in my part of the world and makes me glad for anonymity.
abuse. Please, contact the moderator and ask him to review this thread and give an opinion on what abuse I have given out on this thread and please publish the response. There has been no abuse here. I know there will be no follow up on this one.
Maybe its time to lighten up with this enlightening link.
http://www.successunlimited.co.uk/humour/engineer.htm
Pegase Driver
Thread Starter
Punkalouver:For the record : I am not associated with PBL (nor yourself.)
I am also not an engineer, just a simple Controller with some extra knowledge.
I however think that you should open your mind beyond what you read in the Eurocontrol ACAS bulletins. They are meant for the education of the public users , (i.e pilots and controllers) , and provide standard basic solutions to selected illustrative incidents . They are not the TCAS Bible .They do not cover the philosopy of the system , which is what we try to discuss here.
You said :
We only have one in Europe :so let's take it as an example ( because we all know this one quite well by now) I asume you wrote this because you mean the TU154 pilot ignored TCAS ?
Now this is how I see it :
The collision was not caused ONLY because the 154 ignored TCAS.
To occur this collison needed more :
1) To have both aircraft fitted with TCAS ( because with no TCAS there would not have been a collision ) and
2) for the other aircrfat to follow his RA .
The 757 followed his own RAs more or less as the book said ,and still collided.
(so TCAS did not help/protect him at all )
Finally on this point : based on the regulations in force in July 2002 , it was not irrational for the Tu154 crew to follow the ATC instruction.
Next :
Nobody has. Therefore when I see statements like it is 4 times safer to follow RAs , I smile a bit behind my PC. In any case the numbers are far too small to deduct any useful statistics.
Remaining in Europe ,and only looking at facts : since 1970, there were only 2 high altitude collisions before Ueberlingen.( Nantes in 1973 and Zagred in 1976 ) Those 2 collisions would most probably have been prevented if TCAS would have been available then. However in the period 1976-1994 . No collision and No TCAS either. For the period 1994 -2000 a large portion of aircraft at High altitude in Europe were fitted with TCAS , but not all, especially not those of the former Soviet Union States .Again no collision during that period.
But since mandatory carriage of TCAS in Europe ( 2000) 2 years later one collision partlially caused by TCAS.
So, allow me to question the philosophical statement that " TCAS is good for you "
So when you say that ( quoting you ) :
I also smile a bit. We did not have a collision in 26 years despite many , many millions of flights in that period, and suddendly, we now have a system that would have saved dozens of collisons every year ?
TCAS was introduced in the USA without a proper safety case , for political reasons. It was later introduced in Europe for legal reasons (it would not have been sustainable legally for a State to have a collision in its airspace that could have been prevented by a system that was technically available then ).
Now it is its technical ( in abroad sense ) shortcomings that are being discussed.
I am also not an engineer, just a simple Controller with some extra knowledge.
I however think that you should open your mind beyond what you read in the Eurocontrol ACAS bulletins. They are meant for the education of the public users , (i.e pilots and controllers) , and provide standard basic solutions to selected illustrative incidents . They are not the TCAS Bible .They do not cover the philosopy of the system , which is what we try to discuss here.
You said :
actual collisions caused by ignoring TCAS
Now this is how I see it :
The collision was not caused ONLY because the 154 ignored TCAS.
To occur this collison needed more :
1) To have both aircraft fitted with TCAS ( because with no TCAS there would not have been a collision ) and
2) for the other aircrfat to follow his RA .
The 757 followed his own RAs more or less as the book said ,and still collided.
(so TCAS did not help/protect him at all )
Finally on this point : based on the regulations in force in July 2002 , it was not irrational for the Tu154 crew to follow the ATC instruction.
Next :
I have no technical engineering or studies to give mathematical probabilities of how much safer it is to follow the RA in the midair collision incident.
Remaining in Europe ,and only looking at facts : since 1970, there were only 2 high altitude collisions before Ueberlingen.( Nantes in 1973 and Zagred in 1976 ) Those 2 collisions would most probably have been prevented if TCAS would have been available then. However in the period 1976-1994 . No collision and No TCAS either. For the period 1994 -2000 a large portion of aircraft at High altitude in Europe were fitted with TCAS , but not all, especially not those of the former Soviet Union States .Again no collision during that period.
But since mandatory carriage of TCAS in Europe ( 2000) 2 years later one collision partlially caused by TCAS.
So, allow me to question the philosophical statement that " TCAS is good for you "
So when you say that ( quoting you ) :
Publications giving example after example of saves by TCAS,
TCAS was introduced in the USA without a proper safety case , for political reasons. It was later introduced in Europe for legal reasons (it would not have been sustainable legally for a State to have a collision in its airspace that could have been prevented by a system that was technically available then ).
Now it is its technical ( in abroad sense ) shortcomings that are being discussed.
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Originally posted by ATC Watcher
Now it is its technical ( in abroad sense ) shortcomings that are being discussed.
Now it is its technical ( in abroad sense ) shortcomings that are being discussed.
Originally posted by ATC Watcher
TCAS was introduced in the USA without a proper safety case , for political reasons.
TCAS was introduced in the USA without a proper safety case , for political reasons.
1) 25 September 1978; Pacific Southwest 727-200 vs Cessna172; San Diego, CA-143 dead.
2) 6 June 1971; Hughes Airwest DC9-31 vs. F-4; Near Duarte, CA-50 dead.
3) 9 September 1969; Allegheny DC9-31 vs. Piper Cherokee; Near Fairland, IN-84 dead
4) 19 July 1967; Piedmont 727 vs.Cessna 310; Hendersonville, NC-82 dead.
5) 9 March 1967; TWA DC9-14 vs. Beech Baron; Near Urbana, OH-26 dead.
Keep in mind that there have been way more airline flights in the 21 since the L.A. collision than the 21 previous years. This reality is what makes me smile behind my PC.
Originally posted by ATC Watcher
based on the regulations in force in July 2002 , it was not irrational for the Tu154 crew to follow the ATC instruction.
based on the regulations in force in July 2002 , it was not irrational for the Tu154 crew to follow the ATC instruction.
The TU-154 AOM contains general recommendations regarding the use of TCAS. The AOM reference draws attention to the fact that manouvering opposite to TCAS can lead to a collision.
The TU-154 AOM stated that manouvering opposite to the RA is PROHIBITED.
One final thought about the rationality of manouvering visually to avoid that 757(against the RA) based on "engineering facts". Exactly what facts were used to determine that one can successfully visually manouver around this fast moving jet. Is it just assumed that it can be successfuly accomplished or is there actual data on how easily it is done(in daytime, at night, over brightly lit areas, in marginal visibility or with different cloud formations in the background and the illusions they can create with false horizons which I have also seen with northern lights, etc.). If so please publish this engineering data.
Like I said I have no engineering data. But I do have real world knowledge of a midair between two airliners caused by improper evasive action by one of them when none was required due to illusion.
http://www.prop-liners.com/midair.htm
And I know that according to a Flight Safety Foundation(perhaps the best known safety study group) publication, a JAL 747 captain figured the could go against the RA and visually avoid a DC-10. He was right. He missed by 135 meters and only injured 99 people on his plane and lodged a galley cart in the ceiling(following an RA is a one-quarter G manouver by the way).
http://www.flightsafety.org/fsd/fsd_mar04.pdf
And finally our much talked about TU-154 captain who attempted to visually manouver by a 757. Results catastophic.
I eagerly await these "engineering facts".
Last edited by punkalouver; 10th Dec 2007 at 00:06.
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Originally Posted by punkalouver
I fully agree that there are probably technical shortcomings and PBL is quite possibly aware of them. Have never said different
You list five midair collisions in the US in 11 years to 1978, and then there was one in the next 13 years until TCAS was mandated. It is hard to tell what you want to make of these figures, such as they are. But you do not attempt to account for confounding factors, and that omission is going to invalidate any conclusions you may want to draw.
The most obvious confounding factors are that there were two major revisions of airspace in the U.S. in those thirteen years from 1978 to 1991. The introduction of TCAs and then "Class" airspace had far more effect of separating commercial fast jets from GA traffic than any technical collision avoidance system could have had. If you think the midair collision figures say anything at all, then they say at least that.
PBL
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Originally Posted by punkalouver
It has been over 21 years now since the midair collision over L.A. of a DC-9 and a mode-C equipped Piper.
Originally Posted by Investigation Report
N4891F was equipped with a NARCO Model AT-50A transponder without a mode C altitude encoder.
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Originally Posted by punkalouver
From the final report in part:
The TU-154 AOM contains general recommendations regarding the use of TCAS. The AOM reference draws attention to the fact that manouvering opposite to TCAS can lead to a collision.
The TU-154 AOM stated that manouvering opposite to the RA is PROHIBITED.
The TU-154 AOM contains general recommendations regarding the use of TCAS. The AOM reference draws attention to the fact that manouvering opposite to TCAS can lead to a collision.
The TU-154 AOM stated that manouvering opposite to the RA is PROHIBITED.
The important section (which is diametrically to your "quote") can be found on page 53 in the english report, where the TU154M FOM is quoted (although in translation from russian):
Originally Posted by Investigation Report, p.53
TU154 Flight Operations Manual
[...]
(2) For the avoidance of in-flight collisions is the visual control of the situation in the airspace by the crew and the correct execution of all instructions issued by ATC to be viewed as the most important tool. TCAS is an additional instrument which ensures the timely determination of on-coming traffic, the classification of risk and, if necessary, planning of an advice for a vertical avoidance manoeuvre.
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Originally Posted by punkalouver
And I know that according to a Flight Safety Foundation(perhaps the best known safety study group) publication, a JAL 747 captain figured the could go against the RA and visually avoid a DC-10. He was right. He missed by 135 meters and only injured 99 people on his plane and lodged a galley cart in the ceiling(following an RA is a one-quarter G manouver by the way).