Mid-Air Collision over Southern Germany (merged)
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Garp,
Sorry mate for not replying, had to go to work!! Ages ago, you spoke of 2 aircraft on parallel tracks 5 nm apart having 40 secs to collision if one turned the wrong way. Not true, although ATC separation would be lost.
If you think about the geometry and relative speeds, worst case, the turning aircraft would have to be ahead by about 50° on one side or the other before the turn to make the collision work. Otherwise it would pass safely behind.
That means that it would actually be about 7.5 nm away on the hypotenuse (blah...). Add that to the fact that it will take the aircraft about 15 secs to complete the turn onto the 90° course and you are actually looking at a little more time than you might expect, just over a minute.
The point is that an aircraft on a parallel track turned towards another, with perfect collision geometry, does not create an immediate RA. As an ATC mate you would have about 15 secs before seperation was lost (5nm) and 25 secs even if you didn't spot him turning the wrong way before a TA and about 40 before an RA would be triggered.
For you to have less time, with the aircraft 5 nm seperated, both aircraft would have to turn towards each other.
Hope that helps,
Ghost
Sorry mate for not replying, had to go to work!! Ages ago, you spoke of 2 aircraft on parallel tracks 5 nm apart having 40 secs to collision if one turned the wrong way. Not true, although ATC separation would be lost.
If you think about the geometry and relative speeds, worst case, the turning aircraft would have to be ahead by about 50° on one side or the other before the turn to make the collision work. Otherwise it would pass safely behind.
That means that it would actually be about 7.5 nm away on the hypotenuse (blah...). Add that to the fact that it will take the aircraft about 15 secs to complete the turn onto the 90° course and you are actually looking at a little more time than you might expect, just over a minute.
The point is that an aircraft on a parallel track turned towards another, with perfect collision geometry, does not create an immediate RA. As an ATC mate you would have about 15 secs before seperation was lost (5nm) and 25 secs even if you didn't spot him turning the wrong way before a TA and about 40 before an RA would be triggered.
For you to have less time, with the aircraft 5 nm seperated, both aircraft would have to turn towards each other.
Hope that helps,
Ghost
Last edited by Ghostflyer; 11th Jul 2002 at 08:46.
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The introduction of TCAS into the avaiaton environment has been in my experience very subtle and yet it is such a critical tool in the day to day runing of an Air Traffic environement. I, and I know of many others, had no formal awareness program on the fundemantals of TCAS and the implications it has on ATC. This is especially the case in an environments, such as many expat contracts ME/Asia/Africa, where ongoing knowledge and standards assessment is very loose. Any information and gen on the TCAS issue for example I have researched myself and have been helped by mates who are flying who can give me a better appreciation of the operation of TCAS. If you were to ask a number of Air Traffikers (outside the major institutions perhaps) of the priorities in the event of an RA, I am sure you will be suprised at the number that were not aware the pilots decision will overide any instructions you deem necessary to avoid the conflict. If this is the case in the ATC environment, I am sure there is possibly similar confusion in some of the operator environments. This accident will highlight many deficiencies throughout the industry on the fundementals of TCAS operation and its integration with the ATC environment, lets hope through this sad and unecessary loss, the lessons will not be forgotten and an immediate response to rectify the issues are initiated.
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Fox3Snap, Yes !!
It should also be noted that many of the ATC "contract holders" are often only in it for the $$$$ and thus have no desire or reason to actually improve their staff in terms of courses about things like TCAS, RVSM, FANS-ATM, etc.....
Bottom line, Beancounters don't give a $h!t about safety !!
It should also be noted that many of the ATC "contract holders" are often only in it for the $$$$ and thus have no desire or reason to actually improve their staff in terms of courses about things like TCAS, RVSM, FANS-ATM, etc.....
Bottom line, Beancounters don't give a $h!t about safety !!
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Well said Fox3.
What we had, willy nilly, was a conflict of authority. Either TCAS is the one true god or ATC is. Yes, the rules clearly state TCAS trumps ATC every time, but the Russians thought otherwise. Why?
Just guessing, but I imagine that hitherto this situation had not been clearly foreseen. IOW, up till now most people were imagining scenarios where TCAS would conflict with a pre-existing ATC clearance, in which case no problemo. Here, however, we had an emergency instruction from TCAS more or less simultaneous with another from ATC.
It is not simply a case of Russians having backward SOPs. Last year, two JAL airliners on domestic routes were put on a collision course by a trainee controller. The TCAS on both planes went off with an RA and issued appropriate instructions. At the same time, ATC woke up to its error and ordered, unaware of the conflict with the TCAS instruction, the climbing jet to descend. Climbing jet complies, flies towards its stable mate, they acquire each other visually, manage evasive manoeuvres and, hair having gone white and trousers having been filled, squeak past each other and later land safely.
The Japanese authorities investigated and then requested ICAO to clarify the issue of conflicting emergency advice, which so far I don't think it has. The Japanese were recommending that TCAS always take precedence. It may be there in black and white but if there had been no potential for confusion, why would the Japanese refer it to ICAO?
If the detail of this incident had been circulated maybe the German mid-air might not have happened.
What we had, willy nilly, was a conflict of authority. Either TCAS is the one true god or ATC is. Yes, the rules clearly state TCAS trumps ATC every time, but the Russians thought otherwise. Why?
Just guessing, but I imagine that hitherto this situation had not been clearly foreseen. IOW, up till now most people were imagining scenarios where TCAS would conflict with a pre-existing ATC clearance, in which case no problemo. Here, however, we had an emergency instruction from TCAS more or less simultaneous with another from ATC.
It is not simply a case of Russians having backward SOPs. Last year, two JAL airliners on domestic routes were put on a collision course by a trainee controller. The TCAS on both planes went off with an RA and issued appropriate instructions. At the same time, ATC woke up to its error and ordered, unaware of the conflict with the TCAS instruction, the climbing jet to descend. Climbing jet complies, flies towards its stable mate, they acquire each other visually, manage evasive manoeuvres and, hair having gone white and trousers having been filled, squeak past each other and later land safely.
The Japanese authorities investigated and then requested ICAO to clarify the issue of conflicting emergency advice, which so far I don't think it has. The Japanese were recommending that TCAS always take precedence. It may be there in black and white but if there had been no potential for confusion, why would the Japanese refer it to ICAO?
If the detail of this incident had been circulated maybe the German mid-air might not have happened.
jetsy
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Conflict between TCAS and ATC Instructions
To answer Frangible's question about whether anyone had thought about a real-time conflict between TCAS RAs and ATC instructions, the answer is, 'Yes, way back in March 1991'!
Pilots of UK-registered aeroplanes equipped with TCAS II were required to be trained in accordance with the contents of Civil Air Publication (CAP) 579, published that month, which included the following text:
"Manoeuvres should never be made in a direction opposite to that given in an RA: this is because the sense may have been determined following an exchange of data with the established threat. For this reason:
(a) RAs may be disregarded only when pilots visually identify the potentially conflicting traffic and decide that no deviation from the current flight path is needed.
(b) If pilots receive simultaneously an instruction to manoeuvre from ATC and an RA, and both conflict, the advice given by ACAS (TCAS) should be followed."
The JAA have published similar guidelines in Temporary Guidance Leaflet No 11.
I have no idea what is taught elsewhere around the world.
Pilots of UK-registered aeroplanes equipped with TCAS II were required to be trained in accordance with the contents of Civil Air Publication (CAP) 579, published that month, which included the following text:
"Manoeuvres should never be made in a direction opposite to that given in an RA: this is because the sense may have been determined following an exchange of data with the established threat. For this reason:
(a) RAs may be disregarded only when pilots visually identify the potentially conflicting traffic and decide that no deviation from the current flight path is needed.
(b) If pilots receive simultaneously an instruction to manoeuvre from ATC and an RA, and both conflict, the advice given by ACAS (TCAS) should be followed."
The JAA have published similar guidelines in Temporary Guidance Leaflet No 11.
I have no idea what is taught elsewhere around the world.
Pegase Driver
Avman : Quote from you :
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But had the controller forgotten them completely - and still no TCAS - they would have collided at FL360.
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Caution not to give the wrong idea to the journos scanning this forum for headlines... there is no evidence whatsoever on what you say. And a lot of fellow controllers read this as well.
The fact is that the controler DID spot the conflict and DID issue clearances in trying to resolve it. Late but he did and before TCAS issued RAs .
Do not forget that once one of the pilot announced he was following an RA, responsiblities for separation for both ceases to be with the controller and passes to the pilot(s).
It is not faulty company procedures that caused this collision, it is the ACAS/ATM system incompatibility.
As to the JAL/JAL final report, I have heard it should come out in the next days, and if it contains what I beleive it contains, we are all going to have new ammended TCAS procedures very soon...
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But had the controller forgotten them completely - and still no TCAS - they would have collided at FL360.
------------------------------------------------------------------------------------
Caution not to give the wrong idea to the journos scanning this forum for headlines... there is no evidence whatsoever on what you say. And a lot of fellow controllers read this as well.
The fact is that the controler DID spot the conflict and DID issue clearances in trying to resolve it. Late but he did and before TCAS issued RAs .
Do not forget that once one of the pilot announced he was following an RA, responsiblities for separation for both ceases to be with the controller and passes to the pilot(s).
It is not faulty company procedures that caused this collision, it is the ACAS/ATM system incompatibility.
As to the JAL/JAL final report, I have heard it should come out in the next days, and if it contains what I beleive it contains, we are all going to have new ammended TCAS procedures very soon...
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Bias
To Carruthers:
Whenever I hear of an aviation incident involving a Russian civil aircraft, I wait for the inevitable barrage of accusations directed toward whatever facet of Russian aviation happened to be involved. Sure enough, I was not disappointed in this instance. Even among the very first reports, when actual details regarding the two aircraft were yet unconfirmed, accusations of incompetence were being leveled against the Russian pilots.
This bias against Russian aviation has been perpetrated in the Western media for long enough and is becoming tiresome. I have worked in the civil aviation industry for most of my working life, and most of those I have come in contact with are of the opinion that Russian pilots are among the most skilled and most highly experienced to be found anywhere. The majority have received extensive hands-on training in the military, rather than learning to fly in a classroom at a Western flight school.
Whenever I hear of an aviation incident involving a Russian civil aircraft, I wait for the inevitable barrage of accusations directed toward whatever facet of Russian aviation happened to be involved. Sure enough, I was not disappointed in this instance. Even among the very first reports, when actual details regarding the two aircraft were yet unconfirmed, accusations of incompetence were being leveled against the Russian pilots.
This bias against Russian aviation has been perpetrated in the Western media for long enough and is becoming tiresome. I have worked in the civil aviation industry for most of my working life, and most of those I have come in contact with are of the opinion that Russian pilots are among the most skilled and most highly experienced to be found anywhere. The majority have received extensive hands-on training in the military, rather than learning to fly in a classroom at a Western flight school.
jetsy
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"Russian pilots are among the most skilled and most highly experienced to be found anywhere. The majority have received extensive hands-on training in the military, rather than learning to fly in a classroom at a Western flight school."
Ditto on that one, Gary Ray. The problem (a lot of times) is not the Russian pilots, it's the "chines" they fly.
In this case it was a chain of unfortunate events. As you know, it takes blood at times to have problems fixed. Seems Swiss ATC is working towards improvements.
rgds.
Jet.
Ditto on that one, Gary Ray. The problem (a lot of times) is not the Russian pilots, it's the "chines" they fly.
In this case it was a chain of unfortunate events. As you know, it takes blood at times to have problems fixed. Seems Swiss ATC is working towards improvements.
rgds.
Jet.
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What do you mean by 'skilled' Gary? If you mean throwing Mig29's around at airshows maybe, but then a lot of them hit the ground. It's not the skill of the pilots in pure flying terms that is the problem but the third world equipment they use and their procedures. I find that the western media over hypes Russian achievments, for a recent world super power they don't sell much aviation equipment to anyone. Their mainstay airliners are ancient.
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Let us not lose sight of the following facts about this T154 and it's pilot.
The pilot is reported as been very experienced.
ATC had no apparent communication problems with the russian pilot.
It appears as though the russian pilot complied to TCAS RA, and then adjusted to the (desperate) ATC instruction (as may be the rule in Russia).
The aircraft was not old (younger than the B757).
The aircraft was equiped to European Standards.
SID
The pilot is reported as been very experienced.
ATC had no apparent communication problems with the russian pilot.
It appears as though the russian pilot complied to TCAS RA, and then adjusted to the (desperate) ATC instruction (as may be the rule in Russia).
The aircraft was not old (younger than the B757).
The aircraft was equiped to European Standards.
SID
ATC Watcher , I think that you're misinterpreting what I said. My comments were aimed at the argument for TCAS and my albeit simplified hypothesis was/is:
A) In general but using this case as an example, without TCAS, STCA or Controller intervention the a/c could have collided at their assigned cruising level (this is a presumption).
B) In this particular case, had TCAS RAs been followed without hesitation by both aircraft the evidence provided so far indicates that seperation would have been achieved.
C) In this particular case, even with late controller intervention but say no conflicting TCAS intervention (i.e. no TCAS onboard), again seperation would have been achieved.
I commented (re company procedures) on the basis of what was said in this Forum, that the TU-154 crew reacted to conflicting instructions, one human and one systems, perhaps as the result (once again from what has been said by professionals and official statements posted here) unclear company SOPs and/or training.
I'm not Russian bashing. I was only trying to highlight (the obvious) which is that TCAS is a damn good tool, but for it to be effective, ALL crews worldwide (hence company procedures) must adhere to a uniform response to RAs regardless of conflicting human voice intervention.
A) In general but using this case as an example, without TCAS, STCA or Controller intervention the a/c could have collided at their assigned cruising level (this is a presumption).
B) In this particular case, had TCAS RAs been followed without hesitation by both aircraft the evidence provided so far indicates that seperation would have been achieved.
C) In this particular case, even with late controller intervention but say no conflicting TCAS intervention (i.e. no TCAS onboard), again seperation would have been achieved.
I commented (re company procedures) on the basis of what was said in this Forum, that the TU-154 crew reacted to conflicting instructions, one human and one systems, perhaps as the result (once again from what has been said by professionals and official statements posted here) unclear company SOPs and/or training.
I'm not Russian bashing. I was only trying to highlight (the obvious) which is that TCAS is a damn good tool, but for it to be effective, ALL crews worldwide (hence company procedures) must adhere to a uniform response to RAs regardless of conflicting human voice intervention.
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FYI Alex...
I find that the western media over hypes Russian achievments, for a recent world super power they don't sell much aviation equipment to anyone.
Their mainstay airliners are ancient.
Western mainstay airliner : Boeing 737, first flight 1967.
Russian mainstay airliner : Tu-154, first flight 1968.
I don't mean to be combative with my first post, but I do think that we should be able to separate the facts from the anti-communist propaganda we grew up with.
DW.
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'Flight' survey says ignore TCAS
From http://news.bbc.co.uk/hi/english/wor...00/2124707.stm
Comments ? Anybody here 'surveyed' ?
a poll taken of European pilots by the authoritative Flight International magazine reveals that an overwhelming majority said they would have reacted in exactly the same way as the
Russian aircrew.
Russian aircrew.
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Unbeleivable, what survey of European pilots? Where conducted, by who of whom? Thiis simply cofirms that Flight is about as professional as the Sun. How pray does 'Mr speculation and duff gen Learmont' know the sequence or timing of the TCAS and ATC calls.
As for the 154 being newer than the 757, the 154 is 1950's technology, the Russians did try to build a 757ski but it was a dismal failure even with RB211's.
As for the 154 being newer than the 757, the 154 is 1950's technology, the Russians did try to build a 757ski but it was a dismal failure even with RB211's.
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As for the 154 being newer than the 757, the 154 is 1950's technology, the Russians did try to build a 757ski but it was a dismal failure even with RB211's.
You can't fly RVSM in Europe with 50's Technology. (And that Tu-154 is RVSM approved.)
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HuFac
The system broke down here. With the advent of RVSM this scenario (TCAS II RA at the "levels" as opposed to terminal airspace) was obviously not covered extensively enough for us (ATC) as well as the customers. My understanding is - let him/her go (responding to RA) and pass traffic....deal with your (as in mine - ATC; or yours - bust a level)) f&*ck up later!
Perfect records in Air Safety are what we ever strive for - even though it will always be an asymptote (never reaching zero - planes crash - we learn).
To hit the right mark one must aim above it, for every arrow that flies feels the attraction of the earth.
Henry Wadsworth Longfellow
Carruthers
What you know about "systemic" issues and chains of events in the accident sequence could probably be written on the back of a postage stamp with a crayon! Damned ordinary I'd say considering that the late Capt Hawkins and the eminent Prof Reason hail from your way.
As a controller I find the comments on the last few pages of this thread regarding pilot's perspectives of RAs most informative. Try and stay with it Carruthers old boy no name calling, there's a good chap, be a good man and....
Perfect records in Air Safety are what we ever strive for - even though it will always be an asymptote (never reaching zero - planes crash - we learn).
To hit the right mark one must aim above it, for every arrow that flies feels the attraction of the earth.
Henry Wadsworth Longfellow
Carruthers
What you know about "systemic" issues and chains of events in the accident sequence could probably be written on the back of a postage stamp with a crayon! Damned ordinary I'd say considering that the late Capt Hawkins and the eminent Prof Reason hail from your way.
As a controller I find the comments on the last few pages of this thread regarding pilot's perspectives of RAs most informative. Try and stay with it Carruthers old boy no name calling, there's a good chap, be a good man and....
Last edited by The Crimson Fruitbat; 13th Jul 2002 at 06:17.
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Swiss Concede Partial Responsibility for Crash -
Please see THIS LINK for an Assoicated Press story on this crash where the Swiss "accept partial" responsibility and offer Compensation to the families.
Please see THIS LINK for an Assoicated Press story on this crash where the Swiss "accept partial" responsibility and offer Compensation to the families.