Tcas
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Plumbum Pendular
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From: Avionics Bay
Tcas
Today when working Brest Control we heard a UK LoCo call "TCAS descent". The Brest controller said "Negative, Negative, maintain FLXXX, the aircraft will be levelling off a 1000' above you." Quite rightly the LoCo continued his TCAS descent and told the controller so.
In light of the tragedy over Switzerland a few years ago I can not believe that a controller would actually try and tell a pilot to ignore his TCAS.
I am amazed and admire the pilot's tolerance of the controller. I hope that an MoR was not only filed about the RA but also about the standard of ATC.
In light of the tragedy over Switzerland a few years ago I can not believe that a controller would actually try and tell a pilot to ignore his TCAS.
I am amazed and admire the pilot's tolerance of the controller. I hope that an MoR was not only filed about the RA but also about the standard of ATC.
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From: Malaysia
Yes, even I have to agree to that. For a controller to tell the flight crew to ignore the RA would be something of great folly as this was the very cause of the crash itself in Switzerland a few years back. Even cadets know that.
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From: The frequency jungle
Many ATCOs have already forgotten about that fateful accident and many of the youngsters haven't even heard of it or if they have, don't know any of the details. Sad that a person takes such little interest in their job.......
FWIW, I've never heard an ATCO telling an aircrew to ignore the RA.
FWIW, I've never heard an ATCO telling an aircrew to ignore the RA.
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From: n/a
the aircraft will be levelling off a 1000' above you
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From: Anderlecht
Yes, even I have to agree to that. For a controller to tell the flight crew to ignore the RA would be something of great folly as this was the very cause of the crash itself in Switzerland a few years back. Even cadets know that.
Back to this latest case: yes, absolutely unbelievable. It comes down to poor training and lack of professional discipline.
Pegase Driver
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From: Europe
Very correct reply Avman, thank you.
Topochi : if you had read the report you would have found that at the time the RAs started in both aircraft, none of the crew informed ATC.
(the TU154 crew never informed ATC and the 757 crew did so only 23 seconds later, and even that transmission was blocked by another aircraft )
The causes and factors that led to this collision are many in this case and would take too long to mention their interactions here .
Just make sure the cadets you are talking about have the correct facts .
Back to the subject :
The controller reaction is totally wrong and proves once more the lack of TCAS training / awareness/ refresher training , among too many ATC units .
Equally the importance of the recommendation to reduce vertical rate on the last 1000 Ft of a clearance to avoid RAs is too often not stressed enough to crews.
To understand ( but not to excuse) why we end up with these problems are simple, :
TCAS aims at getting 2 or 300 feet between aircraft, to avoid metal to metal contact . while controllers aim at 1000 ft to avoid loss of separation .
This discrepancy in objectives lead to conflicts ,especially if you have other aircraft in the vicinity of the pair involved, and even more if you have another a/c 1000ft below and opposite to the one which is descending.
Now, since the Ueberlingen collision, we finally have clearer guidelines and recommendations. What is making me extremely worried, is that now, only a couple of years later, we are seeing the same reports as before the collision.
I see ( as part of one of my jobs) an alarming rate of TCAS incidents that prove to me that the lessons of that collision and the recommendations issued thereafter , are not followed and that we are back to where we were before.
In one recent incident , a crew , like in Ueberlingen, followed all the way an ATC clearance that was against the RA issued later . What was “ interesting” for us was that this was involving two major “ established” airlines , and 2 very modern ATC units in the middle of Europe.
This proves to me that unless we ( and I mean by we ICAO, Eurocontrol, the FAA, the UK CAA, etc..) re-open the TCAS training issue rapidly , we are going to have another collision in our skies where TCAS will be involved.
Topochi : if you had read the report you would have found that at the time the RAs started in both aircraft, none of the crew informed ATC.
(the TU154 crew never informed ATC and the 757 crew did so only 23 seconds later, and even that transmission was blocked by another aircraft )
The causes and factors that led to this collision are many in this case and would take too long to mention their interactions here .
Just make sure the cadets you are talking about have the correct facts .
Back to the subject :
The controller reaction is totally wrong and proves once more the lack of TCAS training / awareness/ refresher training , among too many ATC units .
Equally the importance of the recommendation to reduce vertical rate on the last 1000 Ft of a clearance to avoid RAs is too often not stressed enough to crews.
To understand ( but not to excuse) why we end up with these problems are simple, :
TCAS aims at getting 2 or 300 feet between aircraft, to avoid metal to metal contact . while controllers aim at 1000 ft to avoid loss of separation .
This discrepancy in objectives lead to conflicts ,especially if you have other aircraft in the vicinity of the pair involved, and even more if you have another a/c 1000ft below and opposite to the one which is descending.
Now, since the Ueberlingen collision, we finally have clearer guidelines and recommendations. What is making me extremely worried, is that now, only a couple of years later, we are seeing the same reports as before the collision.
I see ( as part of one of my jobs) an alarming rate of TCAS incidents that prove to me that the lessons of that collision and the recommendations issued thereafter , are not followed and that we are back to where we were before.
In one recent incident , a crew , like in Ueberlingen, followed all the way an ATC clearance that was against the RA issued later . What was “ interesting” for us was that this was involving two major “ established” airlines , and 2 very modern ATC units in the middle of Europe.
This proves to me that unless we ( and I mean by we ICAO, Eurocontrol, the FAA, the UK CAA, etc..) re-open the TCAS training issue rapidly , we are going to have another collision in our skies where TCAS will be involved.
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From: uk
There exists the current requirement for specifically training aircrew to follow TCAS RA when in receipt of conflicting ATC instructions, precisely because the frequency of these kind of contradictory directions is significant in ALL busy controlled airspace - before anyone asserts that it is a symptom of general poor ATC standards.
Research has shown that ATCOs mentally sort traffic into two types - those requiring constant monitoring and those who are 'procedurally' separated (as in our case here). When something happens to demand the ATCOs attention to traffic which was considered previously 'separated' then the instinctive reaction to try and either reassert the original instruction (perhaps in denial of a deteriorating situation due to the stress of an impending conflict) or 'rescue' the situation (since despite TCAS now removing the ATCO from the loop the sense of responsibility he/she feels for the traffic is not diminished) it takes considerable mental effort to sit idly by whilst aircraft on your screen are busy doing their own thing in close proximity to one another.
I have seen the same thing many times in tapes of incidents in UK airspace as well: and believe me, the controllers I have trained with here are well aware of their responsibilities when aircraft are in receipt of an RA - it's just often easier said than done, particularly when under unexpected stress.
So don't let's be too quick to criticise the ATCO involved, unless he/she persisted in issuing contradictory instructions - just all take this as a stark lesson in the very real benefit of training for this situation beforehand.
Research has shown that ATCOs mentally sort traffic into two types - those requiring constant monitoring and those who are 'procedurally' separated (as in our case here). When something happens to demand the ATCOs attention to traffic which was considered previously 'separated' then the instinctive reaction to try and either reassert the original instruction (perhaps in denial of a deteriorating situation due to the stress of an impending conflict) or 'rescue' the situation (since despite TCAS now removing the ATCO from the loop the sense of responsibility he/she feels for the traffic is not diminished) it takes considerable mental effort to sit idly by whilst aircraft on your screen are busy doing their own thing in close proximity to one another.
I have seen the same thing many times in tapes of incidents in UK airspace as well: and believe me, the controllers I have trained with here are well aware of their responsibilities when aircraft are in receipt of an RA - it's just often easier said than done, particularly when under unexpected stress.
So don't let's be too quick to criticise the ATCO involved, unless he/she persisted in issuing contradictory instructions - just all take this as a stark lesson in the very real benefit of training for this situation beforehand.
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From: Malaysia
ATC Watcher, Avman: Thank you for pointing the facts out gentlemen. However, the cadets, including myself (also a cadet) are aware of this. My previous post may have been constructed in an ambiguous manner causing some slight misinterpretations and for that, I apologize.
Gary Lager: That makes a whole lot of sense indeed. I suppose that everone has their reasons for carrying out a certain course of action, may it be the flight crew or the ATCO's themselves. All are aiming for a safer and more secure flight. And considering safety has always been the main emphasis in the modern aviation industry, especially during these times, it becomes particularly and increasingly difficult for both the ATCO's and flight crew to carry out their duties without impending stress that would significantly affect their performance. I guess, at times, things can get pretty rough up there.
-Gentlemen, thank you again for pointing out the facts to me. I'm still a cadet, therefore I feel that I may be in no position to comment further. I frequent this site to learn more in so that I may be a more prepared aviator in the near future. Thank you again, and I hope to hear more from you gentlemen by means of forum participation. Cheers!
Gary Lager: That makes a whole lot of sense indeed. I suppose that everone has their reasons for carrying out a certain course of action, may it be the flight crew or the ATCO's themselves. All are aiming for a safer and more secure flight. And considering safety has always been the main emphasis in the modern aviation industry, especially during these times, it becomes particularly and increasingly difficult for both the ATCO's and flight crew to carry out their duties without impending stress that would significantly affect their performance. I guess, at times, things can get pretty rough up there.
-Gentlemen, thank you again for pointing out the facts to me. I'm still a cadet, therefore I feel that I may be in no position to comment further. I frequent this site to learn more in so that I may be a more prepared aviator in the near future. Thank you again, and I hope to hear more from you gentlemen by means of forum participation. Cheers!
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I've gotten into the habit of making all enroute climbs in VS mode these days. (I hear cries of horror from the 'danger! open climb' people, and equally from those who go in fear of the VS you're asking for being too much for the aircraft performance.)
I believe I'm covered on both counts by the fact that open descent and open climb are not a problem on the aircraft type I fly (as it is not on all modern types) - the designers fixed that problem quite some time ago - but many (sometimes quite senior) people seem to be unaware of this fact.
On the performance side of things, the ROC I ask of the aircraft is always less than it would take up if I used VNAV or Level Change.
I do it for two reasons
(a) it gets me into the habit of doing it, so that when it is necessary, as in a heavy traffic RVSM environment and I'm busy, I'll do what I usually do, and
(b) (far less importantly, I accept), is a far more gentle manoeuvre and allows you to make the level change without the pax being aware of any change of engine note.
I believe I'm covered on both counts by the fact that open descent and open climb are not a problem on the aircraft type I fly (as it is not on all modern types) - the designers fixed that problem quite some time ago - but many (sometimes quite senior) people seem to be unaware of this fact.
On the performance side of things, the ROC I ask of the aircraft is always less than it would take up if I used VNAV or Level Change.
I do it for two reasons
(a) it gets me into the habit of doing it, so that when it is necessary, as in a heavy traffic RVSM environment and I'm busy, I'll do what I usually do, and
(b) (far less importantly, I accept), is a far more gentle manoeuvre and allows you to make the level change without the pax being aware of any change of engine note.
Thread Starter
Plumbum Pendular
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From: Avionics Bay
Gary Lager,
I accept your reasoning but I do not agree with you acceptance of incorrect actions.
Is that acceptable? I am sure that for controllers and pilots alike that would not be accepted as a reasonable excuse in one was to balls up in the simulator.
I think that once a controller hears an aircraft call "TCAS xxxxx" then he must just acknowledge it and wait for the resolution to complete.
In the same way I think that many pilots do not consider reducing rates of climb or descent when nearing level off altitudes.
The incident mentioned at the top of this thread was caused by the descending aircraft having a too higher rate of descent.
I accept your reasoning but I do not agree with you acceptance of incorrect actions.
it's just often easier said than done, particularly when under unexpected stress
I think that once a controller hears an aircraft call "TCAS xxxxx" then he must just acknowledge it and wait for the resolution to complete.
In the same way I think that many pilots do not consider reducing rates of climb or descent when nearing level off altitudes.
The incident mentioned at the top of this thread was caused by the descending aircraft having a too higher rate of descent.
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From: the midnight sky
I've gotten into the habit of making all enroute climbs in VS mode these days. (I hear cries of horror from the 'danger! open climb' people, and equally from those who go in fear of the VS you're asking for being too much for the aircraft performance.)
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From: Between a rock
Regardless of what the ATCO said, thats why the boys in the pointy end are paid the big bucks.
It doesn't matter what was said and all may have been well intentioned but this is an example of where the pilot took control of the situation as he/she(?) was trained to do.
Well done guys.
As for ATC if they made a mistake, well it happens sometimes, I mean even I have made one on occasion thankfully my partner in crime saved the day, as usual.
Wiley -
Fair enough but I consider the threat and use the mode most appropriate to the situation, we don't need to dumb down. We need to actively engage with our surrounding environment and behave accordingly. Thats what we are paid to do imho not just thoughtlessly take the easy option. If the skys emtpy use open climb and experience the joy of flight!
Okay, thats enough from me then.
It doesn't matter what was said and all may have been well intentioned but this is an example of where the pilot took control of the situation as he/she(?) was trained to do.
Well done guys.
As for ATC if they made a mistake, well it happens sometimes, I mean even I have made one on occasion thankfully my partner in crime saved the day, as usual.
Wiley -
Fair enough but I consider the threat and use the mode most appropriate to the situation, we don't need to dumb down. We need to actively engage with our surrounding environment and behave accordingly. Thats what we are paid to do imho not just thoughtlessly take the easy option. If the skys emtpy use open climb and experience the joy of flight!
Okay, thats enough from me then.
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From: "this is where the magic happens"
Oh well, nothing suprises me anymore about French ATC. Whether it´s NCE, CDG, ORY or enroute!
There is obviously something very wrong with the way the French train their Air Traffic Controllers!
There is obviously something very wrong with the way the French train their Air Traffic Controllers!
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From: last time I looked I was still here.
I asked this question after the DHL B757 mid-air. No success then, so try again. It might be a Tech forum topic, but the thread is here, now.
Firstly, I believe it is an FAA airspace requirement to have max v/s 1000 in the last 1000', and max 500 in the last 500'. This was even befoe TCAS, and please correct if I am mistaken. If that is correct why did the FAA not also require the a/c manufacturer to program the autpilots to achieve the same? This mode of of operation could have an override button for emergency manoeuvering, but otherwise it would be the norm, or some other settings as thought best; e.g. v/s 1000 in last 1000', as is many airline SOP.
In this day and age of sophisitcated avionics, where the sensitivity of auotpilts is reduced below certain heights on ILS's etc etc. this would be a simple fix. I even heard, after Sioux City, that they tested an autoland using engines only for control. If they can do that, a simple reprogramming of level off technique is simple. I'm still amazed that the autopilot does a good job of reducing 3000 ROC to zero, smoothly, in only 400'.
The requirement for a crew intervention, V/S, into a routine safety manoeuvre, seems not the best method. Further, at high ROC, e.g. 3500, the ALT ACQ trips in well before 1000 to go, and thus the V/S mode is disabled in autopilot ops. The only way the crew can override the A/P and reduce the V/S to avoid an RA, is to disconnect. Hardly ideal.
The solution seems technically so simple. Why no action on the regulators' part?
Firstly, I believe it is an FAA airspace requirement to have max v/s 1000 in the last 1000', and max 500 in the last 500'. This was even befoe TCAS, and please correct if I am mistaken. If that is correct why did the FAA not also require the a/c manufacturer to program the autpilots to achieve the same? This mode of of operation could have an override button for emergency manoeuvering, but otherwise it would be the norm, or some other settings as thought best; e.g. v/s 1000 in last 1000', as is many airline SOP.
In this day and age of sophisitcated avionics, where the sensitivity of auotpilts is reduced below certain heights on ILS's etc etc. this would be a simple fix. I even heard, after Sioux City, that they tested an autoland using engines only for control. If they can do that, a simple reprogramming of level off technique is simple. I'm still amazed that the autopilot does a good job of reducing 3000 ROC to zero, smoothly, in only 400'.
The requirement for a crew intervention, V/S, into a routine safety manoeuvre, seems not the best method. Further, at high ROC, e.g. 3500, the ALT ACQ trips in well before 1000 to go, and thus the V/S mode is disabled in autopilot ops. The only way the crew can override the A/P and reduce the V/S to avoid an RA, is to disconnect. Hardly ideal.
The solution seems technically so simple. Why no action on the regulators' part?
Pegase Driver
Joined: May 1997
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From: Europe
RAT 5, be careful not to mix up requirements ( e.g mandatory) with recommendations.
quick facts to help a few answers :
TCAS software was initially designed for the US domestic lower airspace, ( where the vast majority of the collisions were )
Aim was IFR/VFR protection first, IFR/IFR as a by product. It was regognised from the outset that in the upper aispace with ( very ) fast speeds and CPAs the system will behave badly.
To fly IFR ( outside RVSM ) an Auto pilot is not required.
last : TCAS III ( the lateral version ) was officially abandonned. ( although private studies still go on, but with extremely low chances of getting one day implemented )
Current flavour for the after-TCAS II era, is for a (much better ) anti collision system based on ADS-B.
quick facts to help a few answers :
TCAS software was initially designed for the US domestic lower airspace, ( where the vast majority of the collisions were )
Aim was IFR/VFR protection first, IFR/IFR as a by product. It was regognised from the outset that in the upper aispace with ( very ) fast speeds and CPAs the system will behave badly.
To fly IFR ( outside RVSM ) an Auto pilot is not required.
last : TCAS III ( the lateral version ) was officially abandonned. ( although private studies still go on, but with extremely low chances of getting one day implemented )
Current flavour for the after-TCAS II era, is for a (much better ) anti collision system based on ADS-B.
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NiteKos, it’s my own preference, but company SOPs don’t prohibit it.
jetset, I’d take issue with you that I’m ‘dumbing down’ the operation in using VS mode. I’d say that what I’m doing is quite the opposite. The pax aren’t disturbed by a change in engine pitch, I’m probably saving a nanofart of fuel in not increasing RPM quite as much as a VNAV climb, and (far more importantly) I’m using a procedure every time (unless I’m asked to expedite the climb) that will ensure I won’t be responsible for some poor sod having to carry out a TCAS avoidance manoeuvre.
I take it from your lack of understanding of the term “open climb” that you’re not an airline pilot.
jetset, I’d take issue with you that I’m ‘dumbing down’ the operation in using VS mode. I’d say that what I’m doing is quite the opposite. The pax aren’t disturbed by a change in engine pitch, I’m probably saving a nanofart of fuel in not increasing RPM quite as much as a VNAV climb, and (far more importantly) I’m using a procedure every time (unless I’m asked to expedite the climb) that will ensure I won’t be responsible for some poor sod having to carry out a TCAS avoidance manoeuvre.
I take it from your lack of understanding of the term “open climb” that you’re not an airline pilot.
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From: Greystation
fmgc wrote:
Not at all, you can expect UK controllers at least give you traffic information including whatever their clearance was (ie. descending to maintain 1000' on top) and if the conflict looks close you will also get avoiding action in the horizontal plane. Subsequent updates on traffic information will be passed if thought pertinent until you report "resolution finished, returning to level".
I think that once a controller hears an aircraft call "TCAS xxxxx" then he must just acknowledge it and wait for the resolution to complete.