Mid-Air Collision over Southern Germany (merged)
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Rice Whine
Rather strange that you so swiftly dismiss statements by (in your own words) "public officials" as "rumour and inuendo (sic) ". The public officials on record include the D.A. as well as Frank Göldner (German BFU).
Do you have more reliable information on good authority? Are you saying that the presence of a third person at Zurich ACC on the night of the disaster is an unsubstantiated rumour?
Do you have more reliable information on good authority? Are you saying that the presence of a third person at Zurich ACC on the night of the disaster is an unsubstantiated rumour?
Keeping Danny in Sandwiches
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Do the Middle East registered DHL 757 have TCAS on the EHSI or on the VSI?
The VSI has no range selector and is short range and definitely second best.
The VSI has no range selector and is short range and definitely second best.
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Alpha Leader,
Do you have any knowledge concerning SOP's and working procedures in Zurich ACC?
Do you have any knowledge about the role of a CA (Controller Assistant) in Zurich ACC?
Do you reckon, that you can judge the significance of the presence of a CA on the night of the accident?
Do you have any knowledge concerning SOP's and working procedures in Zurich ACC?
Do you have any knowledge about the role of a CA (Controller Assistant) in Zurich ACC?
Do you reckon, that you can judge the significance of the presence of a CA on the night of the accident?
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Except for the initial info from the T154 CVR, there has been no other info; Radar Recordings, B757 CVR, DFR's, ATC Voice Recorders etc........... seems like a lid has suddenly been put on all info...
SID
SID
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TCAS and the mid-air over Germany
We are all saddened by this incident. As an ATC I feel for my colleagues, as a sometime passenger, I feel for pilots.
That said, I feel that our aviation system needs to decide which form of separation it wants. Either you employ ATCs to keep you apart or you rely on TCAS.
We have now seen the tragic possibilities which result from a pilot relying on two conflicting systems of separation. Imagine for a moment that neither aircraft had TCAS. Would the collision have occurred? Unlikely, as the ATC instruction would have been obeyed on receipt.
I realise this will not please some people, but what are your thoughts?
That said, I feel that our aviation system needs to decide which form of separation it wants. Either you employ ATCs to keep you apart or you rely on TCAS.
We have now seen the tragic possibilities which result from a pilot relying on two conflicting systems of separation. Imagine for a moment that neither aircraft had TCAS. Would the collision have occurred? Unlikely, as the ATC instruction would have been obeyed on receipt.
I realise this will not please some people, but what are your thoughts?
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TCAS is a last resort piece of equipment...IMHO the major change needed is for the datablocks for all aircraft recieving a TCAS RA to change color, or flash so the ATC controller is aware the aircraft is responding to a TCAS command...thus the controller is aware the aircraft is under TCAS command, not that of atc. As pilots we are aware of this, but the atc folks should be as well, so as to avoid issuance of conflicting atc clearances...tcas does not get distracted, it's "transmissions" don't get blocked, so in regards to a last minute avoidance maneuver, it must be (and is to date) the controlling factor, but I say let's put atc in the loop in some other form than a radio transmission.
The Reverend
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You obviously have to have both and adhere strictly to recommended procedures by following RAs. If European ATC can get it wrong, you should fly in Indian airspace controlled by Calcutta for instance and then ask the question.
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Alpha Leader
..You seem to be missing the point old boy.
I suggest you read my original post more carefully. You may notice that I make no mention of the accuracy of the statement regarding the presence of a third person, only the "rumour and innuendo" included in the statement that implies that the assistant was doing something improper.
I have no doubt that there was an assistant present on that fateful evening. What I am p1ssed about is the statement that SHE may have been using the only serviceable telephone or that SHE might have been distracting the duty controllers. It seems to me that his statement is bordering on libel and was irresponsible ... as have been many statements made by various officials in this instance.
I suggest you read my original post more carefully. You may notice that I make no mention of the accuracy of the statement regarding the presence of a third person, only the "rumour and innuendo" included in the statement that implies that the assistant was doing something improper.
I have no doubt that there was an assistant present on that fateful evening. What I am p1ssed about is the statement that SHE may have been using the only serviceable telephone or that SHE might have been distracting the duty controllers. It seems to me that his statement is bordering on libel and was irresponsible ... as have been many statements made by various officials in this instance.
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I doubt very much that it would be a major revamp if the software used to link TCAS and XPDR can immediately change the XPDR code to 7777 while an RA is issued.
This way ALL stay in the loop, the RA overrules everything, the ATCO may interfere with additional lateral issues and the benefit of both systems (ATC and ACAS) are available with even more precise and quicker information.
A lot of gadges have been developed in our still very young industry, some have gone through a constant adjustment due to unforeseen integration problems, reliability issues etc.
As for me, I am very happy to have all these helpful and assisting aids available, well coordinated it will be an absolute dream.
This way ALL stay in the loop, the RA overrules everything, the ATCO may interfere with additional lateral issues and the benefit of both systems (ATC and ACAS) are available with even more precise and quicker information.
A lot of gadges have been developed in our still very young industry, some have gone through a constant adjustment due to unforeseen integration problems, reliability issues etc.
As for me, I am very happy to have all these helpful and assisting aids available, well coordinated it will be an absolute dream.
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TCAS
As far as i know there is already some equipment available at ATC radar to indicate a TCAS RA on the radar screen.
Could any of the controllers here please correct me?
TCAS itself is (IMHO) a great tool that already has helped to avoid more than 1 midair collision, and i guess noboy can tell us how many really. I am alive myself due to the help of TCAS and I do not want to miss it in my aircraft.
The question now is how can we improve the existing TCAS and can contribute to an even more reliable and safe tool?
Out of question is training for flight crews, as my personal guess is that lack of TCAS training might have been a factor in the Lake Constance accident.
What about a TCAS whishlist for pilots and controllers?
The controllers have things like history after the aircraft symbol on the radar screens, together with an estimated future position in 1, 2 or 5 minutes or whatever they select to have displayed.
Is it a good idea to have the same possibility of history symbols displayed on the navigation display of the pilot? If yes, should it be relative to your own aircraft? Or better in reference to the ground, which itself moves on the moving map? Anyhow it would provide information of the direction of displayed TCAS traffic to the pilot.
On the other hand, does this overload the display? Is there too much information displayed to the pilot? Can the average pilot handle so many information as presented to him? Should he be able to select TCAS on with trails or without trails?
What about transmitting the selected altitude of the AFDS system together with TCAS data? That could indicate a climb or descent intention to other listening systems and could help to negotiate the decision for climb between two TCAS systems. Possibly it could avoid contrary commands from ATC and TCAS systems. Also some false TA could be avoided. And every pilot approaching or departing a high traffic airport would have less stress as he gets less false warnings due to high descent/climb or better said vertical approach rates as the TCAS system is based on closure rates. What is the risk then if a warning is suppressed or delayed? Just to make it clear, I am talking about TA, not RA!
We should remember of the intentions of all the accident investigation. All this research is not done to blame on who caused the accident or who is responsible, it is learn how can we avoid another accident and how can we improve the system in order to avoid another similar accident.
Could any of the controllers here please correct me?
TCAS itself is (IMHO) a great tool that already has helped to avoid more than 1 midair collision, and i guess noboy can tell us how many really. I am alive myself due to the help of TCAS and I do not want to miss it in my aircraft.
The question now is how can we improve the existing TCAS and can contribute to an even more reliable and safe tool?
Out of question is training for flight crews, as my personal guess is that lack of TCAS training might have been a factor in the Lake Constance accident.
What about a TCAS whishlist for pilots and controllers?
The controllers have things like history after the aircraft symbol on the radar screens, together with an estimated future position in 1, 2 or 5 minutes or whatever they select to have displayed.
Is it a good idea to have the same possibility of history symbols displayed on the navigation display of the pilot? If yes, should it be relative to your own aircraft? Or better in reference to the ground, which itself moves on the moving map? Anyhow it would provide information of the direction of displayed TCAS traffic to the pilot.
On the other hand, does this overload the display? Is there too much information displayed to the pilot? Can the average pilot handle so many information as presented to him? Should he be able to select TCAS on with trails or without trails?
What about transmitting the selected altitude of the AFDS system together with TCAS data? That could indicate a climb or descent intention to other listening systems and could help to negotiate the decision for climb between two TCAS systems. Possibly it could avoid contrary commands from ATC and TCAS systems. Also some false TA could be avoided. And every pilot approaching or departing a high traffic airport would have less stress as he gets less false warnings due to high descent/climb or better said vertical approach rates as the TCAS system is based on closure rates. What is the risk then if a warning is suppressed or delayed? Just to make it clear, I am talking about TA, not RA!
We should remember of the intentions of all the accident investigation. All this research is not done to blame on who caused the accident or who is responsible, it is learn how can we avoid another accident and how can we improve the system in order to avoid another similar accident.
Pegase Driver
As said before , downlinking RAs to ATC seem a good idea but impracticable. Most radar retirns take 10 sec, in Zurich 12 seconds update,
Then what do you do as a controller with such (old ) data ?
As far as the current system goes, under (radar ) control it is the responsiblity of the controller to provide separation.
Once a TCAS RA is announced and the pilot decides to follow it , that pilot takes that responsibity for separation. ( i.e away from the controller ) the controller can only pass traffic info and not interfere. Downlinking the RAs with 10 or 12 seconds delay, could provoke reactions that will make things worse.( I am thinking here about corrective reversal RAs , which pilots have to follow within 2,5 sec, for instance ).
Then what do you do as a controller with such (old ) data ?
As far as the current system goes, under (radar ) control it is the responsiblity of the controller to provide separation.
Once a TCAS RA is announced and the pilot decides to follow it , that pilot takes that responsibity for separation. ( i.e away from the controller ) the controller can only pass traffic info and not interfere. Downlinking the RAs with 10 or 12 seconds delay, could provoke reactions that will make things worse.( I am thinking here about corrective reversal RAs , which pilots have to follow within 2,5 sec, for instance ).
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ATC Watcher makes the most valid point of all. TCAS has the most up to date information and if the pilot reacts quickly then he has probably already manouevred before we see anything happening on radar. Whilst it is not an infallible system, it offers a more dynamic solution than a last second radar based decision.
Keeping Danny in Sandwiches
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ATC Watcher
I do wonder if the answer if for separation to be taken away from ATC when the TA is activated which would give everyone a little bit more time to think. The problem with the RA is when it happens there is little if any thinking time.
I do wonder if the answer if for separation to be taken away from ATC when the TA is activated which would give everyone a little bit more time to think. The problem with the RA is when it happens there is little if any thinking time.
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As an ATCO there's only one conclusion coming out of this accident:
If you ever experience a similar situation, don't give any descend or climb instruction, but let TCAS do the job.
As long as ATCOs don't get to know the information displayed by TCAS (either by pilot's report or datalink air-to-ground), this will be the only solution to prevent a similar tragedy from happening again.
On the other hand, if it is true, that there is no recommended procedure concerning following an RA, which applies worldwide, then there has to be done something about this immediately ! (In fact, ICAO should have done something about it a long time ago!)
If you ever experience a similar situation, don't give any descend or climb instruction, but let TCAS do the job.
As long as ATCOs don't get to know the information displayed by TCAS (either by pilot's report or datalink air-to-ground), this will be the only solution to prevent a similar tragedy from happening again.
On the other hand, if it is true, that there is no recommended procedure concerning following an RA, which applies worldwide, then there has to be done something about this immediately ! (In fact, ICAO should have done something about it a long time ago!)
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I think the TCAS downlink funktion should not only be understood as air-to-ground, it should also be understood as air-to-air.
Right now the air-to-air function consists of (historic) altitude or mode "C" transmissions upon which the other aircrafts are displayed on the own TCAS relative to own altitide.
If there were an additional information of the AFDS selected altitude, additionaly to the hard facts of historic altitude information a (very) short view into the future would be possible as the Intended altitude could be known by all other receiving parties.
In this way there would be a possibility for TCAS designers to implement a rule to the computer to coordinate commands for the other conflicting system to flee opposite to the intended altitude (relative to present altitude).
Just imagine: The TU had a descent clearance and started descent, the Boeing was very close to the TU and both TCAS computers talked to each other. I am not a TCAS systems engineer, but I can guess the chance to coordinate a climb or descent between the two TCAS computers is 50%.
If the TU TCAS could have told the Boeing TCAS that it wants to descent anyway to a lower level, what would have been the chance to coordinate a climb for the Boeing instead of a descent?
Of course due to reaction time a controller has no chance to intervene and a downlink to ATC would be more of informal character.
Right now the air-to-air function consists of (historic) altitude or mode "C" transmissions upon which the other aircrafts are displayed on the own TCAS relative to own altitide.
If there were an additional information of the AFDS selected altitude, additionaly to the hard facts of historic altitude information a (very) short view into the future would be possible as the Intended altitude could be known by all other receiving parties.
In this way there would be a possibility for TCAS designers to implement a rule to the computer to coordinate commands for the other conflicting system to flee opposite to the intended altitude (relative to present altitude).
Just imagine: The TU had a descent clearance and started descent, the Boeing was very close to the TU and both TCAS computers talked to each other. I am not a TCAS systems engineer, but I can guess the chance to coordinate a climb or descent between the two TCAS computers is 50%.
If the TU TCAS could have told the Boeing TCAS that it wants to descent anyway to a lower level, what would have been the chance to coordinate a climb for the Boeing instead of a descent?
Of course due to reaction time a controller has no chance to intervene and a downlink to ATC would be more of informal character.
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like maybe an input from the aircraft's altitude selector (mcp on 757) to the tcas....interesting...but maybe open to too many malfunction possibilities....my opinion is K.I.S.S. Keep It Simple (and) Safe. TCAS did do it's job, the Bashkirian crew ignored theirs in favor of an almost simultaneous repeat of an atc clearance to descend.....ironically and sadly 10 yrs ago the accident wouldn't have happened, because the dhl aircraft would have obliviously continued along at FL360
Last edited by ironbutt57; 18th Jul 2002 at 05:39.
Keeping Danny in Sandwiches
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A "trawl" with Google produced this page from Rannock. It indicates only a 40 sec activation of the TA and 25sec activation of the RA. I don't know how this timings fit in with ATC instructions and what happened.
http://www.rannoch.com/tcasf.html
Their main TCAS page is also informative
http://www.rannoch.com/TCASMain.html
http://www.rannoch.com/tcasf.html
Their main TCAS page is also informative
http://www.rannoch.com/TCASMain.html