T-cas Descent
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Ok some valid points WestCoast, but with regards using TCAS for traffic awareness when requesting level change, you still don't see my point.
Fine so you see opposite traffic above you 20NM out. So you don't make the request. What you don't see is traffic above you converging in 8 minutes, opposite traffic 100NM out. This is still traffic to affect your potential climb. If you make the request regardless of what you see on your TCAS we might be able to put you on a heading to keep you clear of the traffic you dont see, so that as soon as you cross the traffic you do see you can climb. Waiting till you are clear to put your request might result in more delay. Its simple, the sooner we know what you want the quicker we can plan for it. How do you know the traffic you see opposite at 20NM above you is not MIL traffic on excersize? If thats the case it will turn away from you very quickly and you would get climb straight away. I would know this because I am in contact with the MIL controller. You are not. I cant stress this enough....TCAS does NOT give you SA, not even a little bit. All it does from a radar perspective is lets you know where other aircraft are in relation to you, within a very limited scope.
I'm not disagreeing with most of what you say, I dont even have a PPL, operationally I know very little about TCAS, if you say it helps for various reasons other than collision avoidance I will take your word for it, and thats great. But take my word for it....and every controllers word for that matter....it does not give you SA. Make your request and let us deal with it, if you see traffic on your display then feel free to question a clearance, even mention the traffic when you make a request, but let us know what you want when you want it.
As regards definition, you hit the nail on the head, so do I. Potential threats, under TCAS definition, happen regularly. We as controllers have had to change our working methods to try and avoid TCAS RA's....this has nothing to do with safety, just avoiding paperwork and unnecassary losses of separation. Pilots seem more at one with the idea of having TCAS controlled losses of separation than ATC controlled maintenance of separation. Sure humans make mistakes, are you saying TCAS is flawless?
"This flight is perfectly safe. It is fully automated using the best technology known to mankind. Nothing can go wrong..........wrong.........wrong...........wrong.......... "
Fine so you see opposite traffic above you 20NM out. So you don't make the request. What you don't see is traffic above you converging in 8 minutes, opposite traffic 100NM out. This is still traffic to affect your potential climb. If you make the request regardless of what you see on your TCAS we might be able to put you on a heading to keep you clear of the traffic you dont see, so that as soon as you cross the traffic you do see you can climb. Waiting till you are clear to put your request might result in more delay. Its simple, the sooner we know what you want the quicker we can plan for it. How do you know the traffic you see opposite at 20NM above you is not MIL traffic on excersize? If thats the case it will turn away from you very quickly and you would get climb straight away. I would know this because I am in contact with the MIL controller. You are not. I cant stress this enough....TCAS does NOT give you SA, not even a little bit. All it does from a radar perspective is lets you know where other aircraft are in relation to you, within a very limited scope.
I'm not disagreeing with most of what you say, I dont even have a PPL, operationally I know very little about TCAS, if you say it helps for various reasons other than collision avoidance I will take your word for it, and thats great. But take my word for it....and every controllers word for that matter....it does not give you SA. Make your request and let us deal with it, if you see traffic on your display then feel free to question a clearance, even mention the traffic when you make a request, but let us know what you want when you want it.
As regards definition, you hit the nail on the head, so do I. Potential threats, under TCAS definition, happen regularly. We as controllers have had to change our working methods to try and avoid TCAS RA's....this has nothing to do with safety, just avoiding paperwork and unnecassary losses of separation. Pilots seem more at one with the idea of having TCAS controlled losses of separation than ATC controlled maintenance of separation. Sure humans make mistakes, are you saying TCAS is flawless?
"This flight is perfectly safe. It is fully automated using the best technology known to mankind. Nothing can go wrong..........wrong.........wrong...........wrong.......... "
433
Your point is taken and I concede about level changes. I will no longer wait to request till the traffic I see in no longer a confliction. There have been in the past been times in the past when a pilot who had TCAS would ask for higher/lower only to receive a smart ass comeback by ATC about seeing traffic on said TCAS. They are the exception by far but they unfortunately helped shape the way I did business.
As to TCAS not improving my SA, that simply is incorrect. Anything that improves my overall picture of the safe operation of the aircraft without overloading me is beneficial. Be that picture literally by looking at the TCAS or otherwise from other systems. One simple example as I have errands to run. I am required to respond to a RA if I don't have the other aircraft in sight. If I see a potential confliction developing on the TCAS I will make it a priority to find the traffic prior to what I believe will end in a RA. If spotted I then make my decision to avoid based in large part by visual means. A guy opposite direction but offset left or right will activate a RA which I must respond to. If however I see him on TCAS prior to the RA and determine him to be no factor visually I will not respond to the RA. That is one simple example how my SA is improved.
Is TCAS flawless? No but neither are humans. The midair recently (I think it was Germany) between the Russian made aircraft and the 757 illustrates my point. For purposes of this discussion I don't care how the situation came to be or look to place blame. If however the pilots had complied with the RA rather then the controller who countermanded it the crash likely would not have happened.
You make a pretty sweeping generalization about pilots and the TCAS/ATC interface. Where do you come to this conclusion?
ATC is in my mind the primary source of separation. I believe this to be the mindset of most pilots. If not by belief certainly by company procedures. The day ATC and my fellow pilots are found to be perfect then and only then will I relinquish my role as the Pilot in Command. As long as we as humans are fallible I want another last chance at surviving a mistake by any one of us that can cause a midair.
Your point is taken and I concede about level changes. I will no longer wait to request till the traffic I see in no longer a confliction. There have been in the past been times in the past when a pilot who had TCAS would ask for higher/lower only to receive a smart ass comeback by ATC about seeing traffic on said TCAS. They are the exception by far but they unfortunately helped shape the way I did business.
As to TCAS not improving my SA, that simply is incorrect. Anything that improves my overall picture of the safe operation of the aircraft without overloading me is beneficial. Be that picture literally by looking at the TCAS or otherwise from other systems. One simple example as I have errands to run. I am required to respond to a RA if I don't have the other aircraft in sight. If I see a potential confliction developing on the TCAS I will make it a priority to find the traffic prior to what I believe will end in a RA. If spotted I then make my decision to avoid based in large part by visual means. A guy opposite direction but offset left or right will activate a RA which I must respond to. If however I see him on TCAS prior to the RA and determine him to be no factor visually I will not respond to the RA. That is one simple example how my SA is improved.
Is TCAS flawless? No but neither are humans. The midair recently (I think it was Germany) between the Russian made aircraft and the 757 illustrates my point. For purposes of this discussion I don't care how the situation came to be or look to place blame. If however the pilots had complied with the RA rather then the controller who countermanded it the crash likely would not have happened.
You make a pretty sweeping generalization about pilots and the TCAS/ATC interface. Where do you come to this conclusion?
ATC is in my mind the primary source of separation. I believe this to be the mindset of most pilots. If not by belief certainly by company procedures. The day ATC and my fellow pilots are found to be perfect then and only then will I relinquish my role as the Pilot in Command. As long as we as humans are fallible I want another last chance at surviving a mistake by any one of us that can cause a midair.
Ohcirrej
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Westy, thanks for taking the time to give some well thought out insight into the "other uses". Please don't get me wrong, this wasn't a finger pointing exercise, merely highlighting something that somebody else here may read and think "Aw crap. I've done that" without actually realising how unhelpful it can be. As you say, enough said (how did I know you'd respond? You must be a predictable as me 
)
BTW, for my own sanity, did I dream up that trial for using TCAS for climb through over the Atlantic (I'm fairly sure it was before RVSM kicked off!)?
)BTW, for my own sanity, did I dream up that trial for using TCAS for climb through over the Atlantic (I'm fairly sure it was before RVSM kicked off!)?
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Jerrico,
Yes and no- It was over the Pacific!
Heres a link to more about the trial that was run- para 4.2.4 on.
Can't find out if the trial was successful or not
- maybe Scott has contacts in Oakland Centre
Yes and no- It was over the Pacific!
Heres a link to more about the trial that was run- para 4.2.4 on.
Can't find out if the trial was successful or not
- maybe Scott has contacts in Oakland Centre
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If however I see him on TCAS prior to the RA and determine him to be no factor visually I will not respond to the RA.
Join Date: Aug 2004
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Folks,
you really can find some good info on how/when and why the system works, and answers to the initial question here:
http://www.eurocontrol.int/acas/[/URL]
Suffice to say, that a better understanding of the system techniques required along with capabilities and design/performance criteria could avoid misunderstandings, and errors such as recently tragically occurred.
Fly safe
you really can find some good info on how/when and why the system works, and answers to the initial question here:
http://www.eurocontrol.int/acas/[/URL]
Suffice to say, that a better understanding of the system techniques required along with capabilities and design/performance criteria could avoid misunderstandings, and errors such as recently tragically occurred.
Fly safe
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West Coast, I agree with nearly 100% of what you said so far, but this?
Great. And I'm the pilot in the other aircraft. I haven't seen you, so I respond to the RA. You don't. What happens? Exactly, my RA changes to an 'Increase climb/descent, Increase climb/descent.'
Not reacting to the RA you receive will result in the other aircraft being issued a far more extreme RA. This, surely, is not what you intended?
And ofcourse, I agree with Daysleeper 100% as well, he might not be the one the TCAS is on about!
433,
I understand your points 100%. However, saying TCAS doesn't improve our SA even a little bit is completely incorrect. Even if it shows me only one aircraft, somewhere around me, it's improved my SA. Westy's example of keeping distance on a visual approach, or anticipating wake turbulence, are other examples. All these little things are part of our SA.
However, as said, I agree with the fact that most pilots seem to think it gives them even 1% of your picture, and I recognize that it doesn't, at all.
If however I see him on TCAS prior to the RA and determine him to be no factor visually I will not respond to the RA.
Not reacting to the RA you receive will result in the other aircraft being issued a far more extreme RA. This, surely, is not what you intended?
And ofcourse, I agree with Daysleeper 100% as well, he might not be the one the TCAS is on about!
433,
I understand your points 100%. However, saying TCAS doesn't improve our SA even a little bit is completely incorrect. Even if it shows me only one aircraft, somewhere around me, it's improved my SA. Westy's example of keeping distance on a visual approach, or anticipating wake turbulence, are other examples. All these little things are part of our SA.
However, as said, I agree with the fact that most pilots seem to think it gives them even 1% of your picture, and I recognize that it doesn't, at all.
If I'm doing a close in parallel visual approach to 28L at SFO with traffic lined up for 28R beside me stabilized on final to his runway yet setting off the box due to prox do you expect me to execute the RA? I am not allowed by SOP to select TA only unless we have an engine failure or it automatically done below 1000 AGL. This leaves me two options, follow the RA or continue the approach with the traffic in sight. I'll never land in SFO if I can't accept a visual with someone in close prox for the other runway.
If I'm descending into DFW on one of the arrivals that descends to 11 and see traffic that will pass behind me climbing to 10 with no one else on the TCAS for miles. A RA occurs on the aircraft that the TCAS shows to be the same one I am looking at visually but could not hit me even if he wanted to, I'm not going to comply with the RA.
As evidenced by this thread I am a believer in the box. I however know its limitations and its wide scope of considered threats.
There are times when its safe, or even safer to not follow the RA. Just the same there are times when without question one must follow. Absolute reliance on the box or ATC is not healthy, a bit of common sense must be interjected.
If I'm descending into DFW on one of the arrivals that descends to 11 and see traffic that will pass behind me climbing to 10 with no one else on the TCAS for miles. A RA occurs on the aircraft that the TCAS shows to be the same one I am looking at visually but could not hit me even if he wanted to, I'm not going to comply with the RA.
As evidenced by this thread I am a believer in the box. I however know its limitations and its wide scope of considered threats.
There are times when its safe, or even safer to not follow the RA. Just the same there are times when without question one must follow. Absolute reliance on the box or ATC is not healthy, a bit of common sense must be interjected.
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West coast,
That's not what you were talking about. The situation of parallel approaches is completely different (and no, I wouldn't expect you to follow that RA) than that of opposite offset traffic approaching you mentioned before.
Also, "with no one else on the TCAS for miles" is a very dangerous statement. Due to saturation issues (and yes, TCAS saturation can occur even if there's not many aircraft around), there may not be anyone else on TCAS for miles, but there may be some aircraft around you. You may still be looking at someone else than the RA is looking at, even with your TCAS display empty.
Still, in the situation you describe, you may be putting your collegue in a very awkward position (believe me, I've been there, and it's not a comfortable RA that results from the other guy not doing anything). I think you should also consider that. It's not just you, it's a coordination between two aircraft.
That's not what you were talking about. The situation of parallel approaches is completely different (and no, I wouldn't expect you to follow that RA) than that of opposite offset traffic approaching you mentioned before.
Also, "with no one else on the TCAS for miles" is a very dangerous statement. Due to saturation issues (and yes, TCAS saturation can occur even if there's not many aircraft around), there may not be anyone else on TCAS for miles, but there may be some aircraft around you. You may still be looking at someone else than the RA is looking at, even with your TCAS display empty.
Still, in the situation you describe, you may be putting your collegue in a very awkward position (believe me, I've been there, and it's not a comfortable RA that results from the other guy not doing anything). I think you should also consider that. It's not just you, it's a coordination between two aircraft.
As an aside, my and most European airlines now have a policy of completeing climbs and descent at 1000FPM for the last 1000' to level off, as this reduced closure rate shouldn't trigger an RA with traffic 1000' above or below.
