Mid Air collision over S Germany
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Hello there Ioco,
Please accept my most sincere condolences for your loss.
The equipment you refer to is called TCAS (Traffic Collision Avoidance System).
There are some parameters of the system that can be configured, one of these parameters is the vertical (height above or below) aspect, the other is range (forward distance).
There is another parameter, angle from the nose (left and right) but I don't know if this is adjustable or not..
Assuming that the other aircraft was inside the angle (in this case about 90 degrees), I believe the maximum distance is about 40 nautical miles.
The aircraft would have been travelling at about 450 knots (ground speed), that equates to about 7.5 nautical miles /minute. Therefore, if all the parameters were set to maximum, and my above assumptions are correct. The other aircraft would have been displayed for about 5 minutes.
Hope this helps.
Please accept my most sincere condolences for your loss.
The equipment you refer to is called TCAS (Traffic Collision Avoidance System).
There are some parameters of the system that can be configured, one of these parameters is the vertical (height above or below) aspect, the other is range (forward distance).
There is another parameter, angle from the nose (left and right) but I don't know if this is adjustable or not..
Assuming that the other aircraft was inside the angle (in this case about 90 degrees), I believe the maximum distance is about 40 nautical miles.
The aircraft would have been travelling at about 450 knots (ground speed), that equates to about 7.5 nautical miles /minute. Therefore, if all the parameters were set to maximum, and my above assumptions are correct. The other aircraft would have been displayed for about 5 minutes.
Hope this helps.
Pegase Driver
J ust to complement what has just been said,
watch out Ioco not to jump to conclusions too hastily.
30 to 40 NM is correct IF the display was set up that way, and if it was the other a/c only appears as a symbol of info, i.e. not to be reacted upon.
Also I doubt very much that the crews were glued to their TCAS screen, as there was no reason at this place, time and Altitude to keep watching the TCAS screen.
The real warning, with an audio, came much, much later. The CVR tapes will tell you exactly how much.
You will know by early next week, as the tapes are damaged and need repair before being exploited.. My sincere condoleances for your loss.
watch out Ioco not to jump to conclusions too hastily.
30 to 40 NM is correct IF the display was set up that way, and if it was the other a/c only appears as a symbol of info, i.e. not to be reacted upon.
Also I doubt very much that the crews were glued to their TCAS screen, as there was no reason at this place, time and Altitude to keep watching the TCAS screen.
The real warning, with an audio, came much, much later. The CVR tapes will tell you exactly how much.
You will know by early next week, as the tapes are damaged and need repair before being exploited.. My sincere condoleances for your loss.
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Hello Ioco,
I wish you and your friend's family all possible strength. And I hope you find some answers quickly.
TCAS is Traffic Alert and Collision Avoidance System. The Alert word is important, because you need to know that TCAS is not just a last-ditch tool, but it also provides information to the crew to supplement their 'situational awareness'.
There are two forms of message that TCAS passes the crew, the first is Traffic Advisory(TA). In this case the system detects that there may be traffic in the vicinity which could pose a threat. However, it obviously has no knowledge of instructions passed to either it's own aircraft or any other by ATC. In this way, it maintains its independence from the rest of the ATC system, but it therefore also at times passes information to the crew which although useful, certainly would not cause or instruct the crew to deviate from their ATC instructions.
The second type of message is a Resolution Advisory (RA), in this case the system detects that the aircraft is in imminent danger of a collision. It calculates the best option to avert this collision, and gives a visual warning and an audible alert (eg 'climb, climb ') to the crew.
It is intended that this instruction from TCAS takes precedence over any instruction from ATC.
In this case it may be that a TA was passed to the crew at around the 90sec/ 1 min stage (note this is entirely speculation!!), but as I mentioned earlier, although this may give some kind of warning to the crew, they will not take any action based on this (although in reality crews very often call the controller and state that they have got a Traffic Advisory, and basically ask for some reassurance).
Not until the 15 to 25 second stage before collision will the TCAS system issue a RA to instruct the crew to take evasive action regardless of their ATC clearances.
Some news programmes I have seen tend to give the impression that TCAS is some kind of automatic flight control system which will climb or descend the aircraft without the crew's involvement. It absolutely is not. It is only a warning and instructive system.
Sincerest condolences,
Lukewarm
I wish you and your friend's family all possible strength. And I hope you find some answers quickly.
TCAS is Traffic Alert and Collision Avoidance System. The Alert word is important, because you need to know that TCAS is not just a last-ditch tool, but it also provides information to the crew to supplement their 'situational awareness'.
There are two forms of message that TCAS passes the crew, the first is Traffic Advisory(TA). In this case the system detects that there may be traffic in the vicinity which could pose a threat. However, it obviously has no knowledge of instructions passed to either it's own aircraft or any other by ATC. In this way, it maintains its independence from the rest of the ATC system, but it therefore also at times passes information to the crew which although useful, certainly would not cause or instruct the crew to deviate from their ATC instructions.
The second type of message is a Resolution Advisory (RA), in this case the system detects that the aircraft is in imminent danger of a collision. It calculates the best option to avert this collision, and gives a visual warning and an audible alert (eg 'climb, climb ') to the crew.
It is intended that this instruction from TCAS takes precedence over any instruction from ATC.
In this case it may be that a TA was passed to the crew at around the 90sec/ 1 min stage (note this is entirely speculation!!), but as I mentioned earlier, although this may give some kind of warning to the crew, they will not take any action based on this (although in reality crews very often call the controller and state that they have got a Traffic Advisory, and basically ask for some reassurance).
Not until the 15 to 25 second stage before collision will the TCAS system issue a RA to instruct the crew to take evasive action regardless of their ATC clearances.
Some news programmes I have seen tend to give the impression that TCAS is some kind of automatic flight control system which will climb or descend the aircraft without the crew's involvement. It absolutely is not. It is only a warning and instructive system.
Sincerest condolences,
Lukewarm
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As these are anonymous forums the origins of the contributions may be opposite to what may be apparent. In fact the press may use it, or the unscrupulous, to elicit certain reactions.,
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To maybe clear up a point, I had an aircraft last week inform me they had just lost their RVSM approved status due to the TCAS packing up. Seem to remember when the trials began over the Atlantic, a/c had to have 2 of 3; INS, GPS, and one other, and only 2 out of 3 needed to work, but then I could just be dreaming.......and things obviously change!!!
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New to this Forum but just heard BBC announce that the Russian pilot told the Swiss ATCO that they had a proximity warning which prompted the order to descend. The Germans say that their controllers had been watching for two minutes and trying to warn Swiss.
God have mercy on the dead and comfort the living
Text from BBC website:
According to German authorities, cockpit warning systems told the Tu-154 to climb and the cargo jet to descend, just 45 seconds before the collision.
But voice recorders reveal that one second later, Zurich air traffic controllers told the Russian pilots to descend.
The Russian crew did not respond, so the Zurich control tower repeated the order 14 seconds later, investigators say.
The Russian plane responded and the two aircraft collided 30 seconds later.
Although the aircraft were flying over Germany at the time, they were under the control of the Swiss air traffic control body, Skyguide.
Investigations are being carried out by both Swiss and German authorities.
The Swiss inquiry is looking into the possibility of homicide through negligence, which carries a three-year jail term for anyone found guilty.
Irregularities
Earlier, the German weekly Der Spiegel reported that German air traffic controllers had tried to warn Skyguide that the planes were on a collision course
But all attempts reportedly failed as the telephone network at Skyguide was down at the time for maintenance.
While Skyguide had initially pointed the finger at the Russian pilot's failure to respond promptly to the air controller's warning, it has been revealed that there were several other irregularities at the control centre on the night in question.
In addition to work apparently being carried out on the telephone network, the centre's collision warning system was down for maintenance and only one controller was on duty at the time of the crash.
The controller, who warned the Russian pilot to change course just 44 seconds before the collision, has been described as overburdened by a German team investigating the crash.
God have mercy on the dead and comfort the living
Text from BBC website:
According to German authorities, cockpit warning systems told the Tu-154 to climb and the cargo jet to descend, just 45 seconds before the collision.
But voice recorders reveal that one second later, Zurich air traffic controllers told the Russian pilots to descend.
The Russian crew did not respond, so the Zurich control tower repeated the order 14 seconds later, investigators say.
The Russian plane responded and the two aircraft collided 30 seconds later.
Although the aircraft were flying over Germany at the time, they were under the control of the Swiss air traffic control body, Skyguide.
Investigations are being carried out by both Swiss and German authorities.
The Swiss inquiry is looking into the possibility of homicide through negligence, which carries a three-year jail term for anyone found guilty.
Irregularities
Earlier, the German weekly Der Spiegel reported that German air traffic controllers had tried to warn Skyguide that the planes were on a collision course
But all attempts reportedly failed as the telephone network at Skyguide was down at the time for maintenance.
While Skyguide had initially pointed the finger at the Russian pilot's failure to respond promptly to the air controller's warning, it has been revealed that there were several other irregularities at the control centre on the night in question.
In addition to work apparently being carried out on the telephone network, the centre's collision warning system was down for maintenance and only one controller was on duty at the time of the crash.
The controller, who warned the Russian pilot to change course just 44 seconds before the collision, has been described as overburdened by a German team investigating the crash.
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Investigators are now saying that the Russian plane received a TCAS resolution to climb, and a descent instruction from the controller which he apparently complied with, the DHL 757 received a resolution advisory to descend.
I wonder why the Russian pilots chose to ignore the resolution to climb, don't they have to follow what the TCAS tells them?
Mike
I wonder why the Russian pilots chose to ignore the resolution to climb, don't they have to follow what the TCAS tells them?
Mike
In response to the post above about TCAS, it is NOT required for flight in RVSM airspace. It is worth noting in the light of this accident that our (and I guess most other operators) TCAS can be out of service for up to 10 days before it is fixed under the current dispatch regulations. During that time the aircraft is still able to fly in RVSM airspace and as far as I know ATC do not have to be informed of the defect. I suspect we may see a reduction in the allowable time to perhaps 24 hours or 3 flights which I think is the time allowed for things like GPWS and flight recorders.
Lets hope that some good can come out of the ashes of this one and things will be a bit safer as a result.
Lets hope that some good can come out of the ashes of this one and things will be a bit safer as a result.
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Hello, gents. This is my first post on this particular site, but visitors to ‘Reporting Points’ may recognise my ‘handle’. If I may use a few random quotes from this thread to illustrate my pet cause, the introduction of offset tracking (which I accept would not have prevented this particular tragedy):
Finally, one last quote from this thread:
My bet is that until a week ago, there would be many of you who would have said: “This could never happen in Western European airspace...
Some of you may care to take the time to read the following two submissions that have been on the Pprune Tech/Safety board for more than five years now:
http://www.pprune.org/go.php?go=/pub/tech/MidAir.html
and
http://www.pprune.org/go.php?go=/pub/tech/MidAir2.html
So do we wait until the scenario ‘Flanker’ gave us in the quote above actually results in a head-to-head midair before we lock yet another proverbial stable door behind a long gone horse? Or do we all, pilots and ATCOs alike, INSIST upon the speedy implementation of an embedded offset for all operations above 10,000’ for appropriately equipped aircraft?
I urge anyone reading this to consider this suggestion beyond (what seems to be) the immediate knee jerk reaction of saying “it can’t be done”. It is not a slight on the professionalism of ATCOs, just an acceptance that mistakes can – and, as has just been proven, do – occur in the most professional organisations. Why do we insist on placing pilots in a position of quite literally dodging speeding bullets when the technology is staring us all in the face that would ensure those ‘speeding bullets’ will pass exactly ‘.n’ miles abeam of them – every time?
From ’Fox3snapshot’: “…my point is that it is still important not to forget the basics of our procedural standards and build a bit of "fat" into the program to allow for, poor comms, possible language problems, co-ordination failures, radar failures etc.”
From ’120.4’: “The first lesson I learned at the college was that in this game sod's law works double but because things rarely go wrong, we have come to expect that they won't.” (my boldface)
From ‘Flanker’: “I was unfortunate enough to have a close, opposite direction same level (FL330) airmiss… Luckily we were VMC and I saw the guy coming.”
“This could never happen in UK airspace...”
Some of you may care to take the time to read the following two submissions that have been on the Pprune Tech/Safety board for more than five years now:
http://www.pprune.org/go.php?go=/pub/tech/MidAir.html
and
http://www.pprune.org/go.php?go=/pub/tech/MidAir2.html
So do we wait until the scenario ‘Flanker’ gave us in the quote above actually results in a head-to-head midair before we lock yet another proverbial stable door behind a long gone horse? Or do we all, pilots and ATCOs alike, INSIST upon the speedy implementation of an embedded offset for all operations above 10,000’ for appropriately equipped aircraft?
I urge anyone reading this to consider this suggestion beyond (what seems to be) the immediate knee jerk reaction of saying “it can’t be done”. It is not a slight on the professionalism of ATCOs, just an acceptance that mistakes can – and, as has just been proven, do – occur in the most professional organisations. Why do we insist on placing pilots in a position of quite literally dodging speeding bullets when the technology is staring us all in the face that would ensure those ‘speeding bullets’ will pass exactly ‘.n’ miles abeam of them – every time?
TCAS Unserviceability Periods
TCAS equipment serviceability has proved to be pretty good, but when a fault does appear, it tends to be something that cannot be fixed by a simple box change. For example, a problem with an aerial may not easily be rectified at a line station.
It is therefore reasonable to allow the aircraft time to return to its major base where rectification can be carried out. Remember, some aeroplanes may be on the other side of the world when the fault materialises. Therefore, the 10 day period has been thought reasonable either to allow that aeroplane to return to base or, if it is a small/medium sized aeroplane without comprehensive spares support facilities at home, time to get a repair kit shipped out.
One other point worth bearing in mind. It is extremely unlikely that two aeroplanes, both with unserviceable TCAS, will find themeselves in a situation that needs TCAS to resolve. Where only one of a pair has serviceable TCAS, the manoeuvre perfomed by its pilots should produce a sufficient difference of altitude to ensure that no collision occurs. (This would be also true if the other aircraft didn't have TCAS anyway.)
It is therefore reasonable to allow the aircraft time to return to its major base where rectification can be carried out. Remember, some aeroplanes may be on the other side of the world when the fault materialises. Therefore, the 10 day period has been thought reasonable either to allow that aeroplane to return to base or, if it is a small/medium sized aeroplane without comprehensive spares support facilities at home, time to get a repair kit shipped out.
One other point worth bearing in mind. It is extremely unlikely that two aeroplanes, both with unserviceable TCAS, will find themeselves in a situation that needs TCAS to resolve. Where only one of a pair has serviceable TCAS, the manoeuvre perfomed by its pilots should produce a sufficient difference of altitude to ensure that no collision occurs. (This would be also true if the other aircraft didn't have TCAS anyway.)
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A few words from one who was close to it:
being an incident investigator at the unit next to Swiss Radar (we expected DHX611)and taking care of our controllers this particular night I was running a few replays of the incident. Emotions were extreme. We saw it coming, our STCA (short time conflict alert) flashed the labels in bright red 132(!) seconds before the impact. Our controllers tried to reach Zürich over all landlines they had but could not get through until it happened. This is a horrible feeling. An incident like this showed up some times before but passed as a "close shave". It´s man against machine; TCAS says acft1 climb, acft2 descend. Controller´s solution is acft1 descend, acft2 climb. Both are ok but should have the same participants. Here we had two solutions with only one participant each. DHX611 (Dilmun) performs a TCAS descent, BTC2937 (Bashkirian)has a corresponding TCAS-RA "climb" but believes the controller and descends, too.
Both acft too close and too fast to let TCAS switch the RA for the "Dilmun" into a climb. Only solution for TCAS: "increase descent". This is from 1.500fpm to 2.500fpm, normally. Such a rate is ridiculous for a TU154 being asked to "expedite descent" . Both acft hit at FL354 in the descent.
Our thoughts are with the victims and with the one survivor: the controller at Skyguide who was in charge. We consider he cannot be happy no more for the rest of his life.
What can we do to solve this "man against machine" problem?
Edited to remove text which could identify the poor soul involved ..... PPRuNe Radar
being an incident investigator at the unit next to Swiss Radar (we expected DHX611)and taking care of our controllers this particular night I was running a few replays of the incident. Emotions were extreme. We saw it coming, our STCA (short time conflict alert) flashed the labels in bright red 132(!) seconds before the impact. Our controllers tried to reach Zürich over all landlines they had but could not get through until it happened. This is a horrible feeling. An incident like this showed up some times before but passed as a "close shave". It´s man against machine; TCAS says acft1 climb, acft2 descend. Controller´s solution is acft1 descend, acft2 climb. Both are ok but should have the same participants. Here we had two solutions with only one participant each. DHX611 (Dilmun) performs a TCAS descent, BTC2937 (Bashkirian)has a corresponding TCAS-RA "climb" but believes the controller and descends, too.
Both acft too close and too fast to let TCAS switch the RA for the "Dilmun" into a climb. Only solution for TCAS: "increase descent". This is from 1.500fpm to 2.500fpm, normally. Such a rate is ridiculous for a TU154 being asked to "expedite descent" . Both acft hit at FL354 in the descent.
Our thoughts are with the victims and with the one survivor: the controller at Skyguide who was in charge. We consider he cannot be happy no more for the rest of his life.
What can we do to solve this "man against machine" problem?
Edited to remove text which could identify the poor soul involved ..... PPRuNe Radar
Last edited by PPRuNe Radar; 10th Jul 2002 at 09:57.
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In all the discussion I see in this and other threads there is one thing that I miss and I think it is something we must not forget. Whatever happens and whatever incidents or accidents may occur, there will always be a very significant difference in approach between Air Traffic Controllers and Pilots and that is the fact that the Pilots life is directly at steak and not the life of the Air Traffic Controller.
All the discussion about lives being ruined anyway cannot take away that fact.
PS.
I am both
All the discussion about lives being ruined anyway cannot take away that fact.
PS.
I am both
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romewiz
<<What can we do to solve this "man against machine" problem>>
Its all laid out - you obey TCAS every time there is a conflict. As shown here, its the "backstop" when ATC or pilots fail to ensure the separation. Its rate of reaction, the fact there are (ideally) 2 co-ordinated actions given, its direct input to the pilot, and the fact it can "see" far quicker than ATC the effect of any action being taken.
What is needed, and probably will come out of this incident, is more training for crews and ATC as to the benefits and pitfalls of TCAS. Benefits mean ATC (and pilots) will hopefully trust it to sort out the vertical separation when things have already "gone wrong" - and restrict their own efforts to lateral separation.
I do not know how much training / sim practice the Russian crew had with TCAS - a guess is it was not enough to pick the correct choice of the 2 shouted instructions.
Whatever ATCOs think of TCAS, and I can understand their warieness of the system, encouraging anyone not to follow the SOPs is what will lead to more incidents like this one. The TCAS RA must be obeyed first, inform ATC when able / ASAP, but keep listening to and obeying that TCAS... The hopefully this will be the last incident of this type...
NoD
<<What can we do to solve this "man against machine" problem>>
Its all laid out - you obey TCAS every time there is a conflict. As shown here, its the "backstop" when ATC or pilots fail to ensure the separation. Its rate of reaction, the fact there are (ideally) 2 co-ordinated actions given, its direct input to the pilot, and the fact it can "see" far quicker than ATC the effect of any action being taken.
What is needed, and probably will come out of this incident, is more training for crews and ATC as to the benefits and pitfalls of TCAS. Benefits mean ATC (and pilots) will hopefully trust it to sort out the vertical separation when things have already "gone wrong" - and restrict their own efforts to lateral separation.
I do not know how much training / sim practice the Russian crew had with TCAS - a guess is it was not enough to pick the correct choice of the 2 shouted instructions.
Whatever ATCOs think of TCAS, and I can understand their warieness of the system, encouraging anyone not to follow the SOPs is what will lead to more incidents like this one. The TCAS RA must be obeyed first, inform ATC when able / ASAP, but keep listening to and obeying that TCAS... The hopefully this will be the last incident of this type...
NoD
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NigelonDraft
Extolling the virtues of TCAS is all well and good - but have you read Nasty Incident . There's a lot more to using TCAS than blind obedience - as this incident points out.
CM
Extolling the virtues of TCAS is all well and good - but have you read Nasty Incident . There's a lot more to using TCAS than blind obedience - as this incident points out.
CM
Last edited by Chilli Monster; 9th Jul 2002 at 17:50.
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Reading my way through this thread, and the one on "Reporting Points", I have found that I have learned more about TCAS in the last week than I ever knew. It has also made me aware of how little we in the UK teach our trainee controllers about TCAS. How much training goes on at operational units on this subject 'cos it's 2/3 of b*gger all at "the place where I work?