When Is A Near Miss NOT A Near Miss??
Join Date: Sep 2001
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One of the problems that TCAS has caused is putting the controllers in a situation where they don't know whether they should give instructions to an aircraft that they believe is responding to an RA. Reading the findings of the SkyGuide disaster, one of the recommendations was for controllers if they believe the pilots are responding to RA's is to pretty much shut up and wait for it all to be over, as by giving instructions you may make the situation worse.
The problem is firstly you are never sure if an RA is being followed as the pilot will usually tell us after he has carried out the avoiding action, secondly our radar info is behind real time, so we may be descending a guy back into a guy he has already climbed above, and finally it is not in our nature to sit on our hands and watch it all turn to "Kak"(sorry been hangin round Sth Africans too much
)
I do still feel that if we are going to make TCAS carriage mandatory (as it is here for all but the really light low stuff, which basically there is none of), then we need to all know the rules we are playing by. Either the pilots have discretion to decide whether they respond or we need to know that the pilots will always follow the TCAS and ignore ATC instructions. I go with the ignore us and always follow the TCAS completely. I understand Ferris's logic of there are cases where both visual etc. but there are also cases where one aircraft takes your advice, and the other one doesn't and when there is 20 seconds or less to decide, I would prefer to have some black and white rather than grey.
BTW Spod, on a previous thread you mentioned the old Rogue pilot. I do remember how he used to always need to divert right of track round weather which took him to WENDY (still makes me quiver when I type that name!!) rather than ARBEY. Amazingly the weather was only present when we were using RWY 34 in Melbourne. Also saw in another post, you're still sitting in the Crisper
The guys on TMA must be gonna drop off the perch soon! A few of them looked like they were close when I left 
The problem is firstly you are never sure if an RA is being followed as the pilot will usually tell us after he has carried out the avoiding action, secondly our radar info is behind real time, so we may be descending a guy back into a guy he has already climbed above, and finally it is not in our nature to sit on our hands and watch it all turn to "Kak"(sorry been hangin round Sth Africans too much
)I do still feel that if we are going to make TCAS carriage mandatory (as it is here for all but the really light low stuff, which basically there is none of), then we need to all know the rules we are playing by. Either the pilots have discretion to decide whether they respond or we need to know that the pilots will always follow the TCAS and ignore ATC instructions. I go with the ignore us and always follow the TCAS completely. I understand Ferris's logic of there are cases where both visual etc. but there are also cases where one aircraft takes your advice, and the other one doesn't and when there is 20 seconds or less to decide, I would prefer to have some black and white rather than grey.
BTW Spod, on a previous thread you mentioned the old Rogue pilot. I do remember how he used to always need to divert right of track round weather which took him to WENDY (still makes me quiver when I type that name!!) rather than ARBEY. Amazingly the weather was only present when we were using RWY 34 in Melbourne. Also saw in another post, you're still sitting in the Crisper
The guys on TMA must be gonna drop off the perch soon! A few of them looked like they were close when I left
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Just a couple of random comments:
As I understand the TCAS does not provide lateral direction, only vertical as a solution to an RA and will desentisise below 1000 feet AGL which must be a bother landing at busy G/CTAF? So even with this form of defence we have imperfectness.
I have some time up at Alice (in my deep, dark and best forgotten past) and this is where I am most concerned for the fast aircraft, because whilst the ATC service comes with high regard the C into E situation with no RADAR and quite dense levels of both Bush and itinerant traffic is clearly an increased hazard with NAS. The upside is that most of this traffic is on predicted routes (which ironically correspond with IFR) which means there is a known quantity. Perhaps a method of traffic management (by crews or ATC) may assist to get fast aircraft off those routes for descent or climb to minimise the hazard - ie IFR route segregation with the majority of VFR.
SPODMAN mentioned "Merging Targer Procedures (MTP - my abbrev.)" which is something ATC have been doing for ever, on a workload permitting basis. My experience at Alice was a F28 departing the Rock for Alice to maintain F280. Just before he called ATC (and got the crossing traffic) he had a heart stopping experience when, in the middle of AUS, on a clear blue day, his cockpit was thrust into darkness, followed by the sight of the large underbelly of a B747 overflying him at F290 on crossing route, T27.
Traffic even in non-RADAR C airspace is a good call - but doesn't need to be War and Peace.
Just thinking that we are getting more and more dependant upon the words "workload permitting". A Claytons service maybe?
As I understand the TCAS does not provide lateral direction, only vertical as a solution to an RA and will desentisise below 1000 feet AGL which must be a bother landing at busy G/CTAF? So even with this form of defence we have imperfectness.
I have some time up at Alice (in my deep, dark and best forgotten past) and this is where I am most concerned for the fast aircraft, because whilst the ATC service comes with high regard the C into E situation with no RADAR and quite dense levels of both Bush and itinerant traffic is clearly an increased hazard with NAS. The upside is that most of this traffic is on predicted routes (which ironically correspond with IFR) which means there is a known quantity. Perhaps a method of traffic management (by crews or ATC) may assist to get fast aircraft off those routes for descent or climb to minimise the hazard - ie IFR route segregation with the majority of VFR.
SPODMAN mentioned "Merging Targer Procedures (MTP - my abbrev.)" which is something ATC have been doing for ever, on a workload permitting basis. My experience at Alice was a F28 departing the Rock for Alice to maintain F280. Just before he called ATC (and got the crossing traffic) he had a heart stopping experience when, in the middle of AUS, on a clear blue day, his cockpit was thrust into darkness, followed by the sight of the large underbelly of a B747 overflying him at F290 on crossing route, T27.
Traffic even in non-RADAR C airspace is a good call - but doesn't need to be War and Peace.
Just thinking that we are getting more and more dependant upon the words "workload permitting". A Claytons service maybe?
Join Date: Jul 2003
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Couple of things
Firstly George
I agree with you that in your situation at that time the levelling of the aircraft at their assigned levels as opposed to responding to the RAs was satisfactory. Unfortunately today these aircraft may think that the traffic giving them the RA is the one they can hear on Centre with a level clearance but there could be some other there happily ploughing along not talking. AN737 assigned FL170 on descent, Southern Dash assigned FL160 on climb and right in between is MGC passing FL165 on climb or descent 1200 on the transponder. Both get RAs.
We now have the unknown in this airspace and I would hope that pilots remember this when they think they have expected traffic sighted.
Secondly
The Merging Target Procedure has ceased to exist. AIC H8/03 (from memory) has expired and through a fabulous bit of stubbornness on both sides, the AIC was not promulgated into MATS or AIP and is no longer in existence. I note that this was never made clear to everyone who had received training in its existence. I only found out due to asking a question that was completely unreleated.
Firstly George
Have had a situation where the aircraft (AN 737 vs Southern Dash8)were fully clued up (traffic passed etc) but due to high rates climb/descent received RAs
We now have the unknown in this airspace and I would hope that pilots remember this when they think they have expected traffic sighted.
Secondly
The Merging Target Procedure has ceased to exist. AIC H8/03 (from memory) has expired and through a fabulous bit of stubbornness on both sides, the AIC was not promulgated into MATS or AIP and is no longer in existence. I note that this was never made clear to everyone who had received training in its existence. I only found out due to asking a question that was completely unreleated.
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To be honest, Plazbot, I hadn't thought of that. Yes, back when mine occurred it was the relatively safe classC. Now, with this NAS rubbish, anyone could be there (not necessarily squawking, either. Wouldn't that be nice- get an RA and have to look out for other VFR traffic {such as C421s at FL175 at CANTY} not necessarily squawking?!?!).
NAS should be stopped until ADSB is available. It's a disaster waiting to happen.
Merging Target Procedure? Isn't that something Fighter Controllers learn? Usual AsA management competence at work, I see.
NAS should be stopped until ADSB is available. It's a disaster waiting to happen.
Merging Target Procedure? Isn't that something Fighter Controllers learn? Usual AsA management competence at work, I see.
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Well ... as you guys talk, at least the Ghost Who Walks and I will be safe if we meet each other as we'll follow our RA's.
As I read this thread I'm appalled to note there are those who would doubt an RA. Doubt the RA and you may join those who have fallen from the sky (God rest their souls).
As for me ... I'll look while it's squawking "Trafiic Traffic", but should it say "Climb, Crossing Climb" that's what I'm gonna do. And you better be doing what it's telling you.
As I read this thread I'm appalled to note there are those who would doubt an RA. Doubt the RA and you may join those who have fallen from the sky (God rest their souls).
As for me ... I'll look while it's squawking "Trafiic Traffic", but should it say "Climb, Crossing Climb" that's what I'm gonna do. And you better be doing what it's telling you.
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As a controller in the London TMA I can say that I have seen alot of instances of unnecessary TCAS warnings. BUT and its a big BUT! the times that TCAS has saved an a/c or two make up for it. In my profession, we are taught that as soon as a pilot says that he is reacting to a TCAS then he is totally responsible for his own separation. TCAS is a last minute separation tool, it will not provide standard separation, it will get you a miss and that is all. If you can guarantee that the a/c you see is the one you are supposed to be missing then fine, but tcas will give you a miss definitely even if your human eye doesn't agree.
Finally as a controller, me and my collegues have had to change our working practises because of TCAS (closure rates etc). In the beginning we thought it was a pain in the preverbial. Now we believe it is essential and would not like to be without it. TCAS has made the environment safer and saved several pilots and controllers from some very nasty situations.
IT WORKS
Finally as a controller, me and my collegues have had to change our working practises because of TCAS (closure rates etc). In the beginning we thought it was a pain in the preverbial. Now we believe it is essential and would not like to be without it. TCAS has made the environment safer and saved several pilots and controllers from some very nasty situations.
IT WORKS
Agree with the most recent posts. A TCAS RA is to followed unless it is clearly unsafe to do so. This was strongly reiterated after the midair over Switzerland (where the Russian aircraft followed the air traffic controller's instruction which unfortunately was contrary to the RA instuction....). And let's not quibble about what "unsafe" means. If the RA is flying you into the ground or clearly into another aircraft that you have visual, then fair enough, don't follow it. But otherwise, do what it says. That is enshrined in QF's SOP's. The integrity of the protection it provides is based on everyone doing the right thing.
It does beg the question how another airline in Aus can be permitted to have a TCAS RA policy where they can elect not to follow an RA if the traffic is sighted (as per the ATSB report)..... Not having a go at DJ blokes as such, but you'd think CASA would be consistent in their application of this matter when approving company Ops manuals... Comments anyone?
It does beg the question how another airline in Aus can be permitted to have a TCAS RA policy where they can elect not to follow an RA if the traffic is sighted (as per the ATSB report)..... Not having a go at DJ blokes as such, but you'd think CASA would be consistent in their application of this matter when approving company Ops manuals... Comments anyone?
