TCAS mod req'd?
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TCAS mod req'd?
Rumour has it that recently an airliner had a 'false' TCAS warning after it was triggered by a number of red aircraft spilling out of the top of R313?
Perhaps the civvies need a TCAS filter to ignore formations of more than 4 aircraft?
Perhaps the civvies need a TCAS filter to ignore formations of more than 4 aircraft?
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Mud raking here I suspect. TCAS is designed to give warnings based on RoC - it couldve been at FL200 over the top and still received a TA or maybe even an RA. Anyone who has flown using TCAS with Typhoon about will know what I mean.
Non-event
(Anyway, who flies over the top of the 313 believing the Reds would never break FL95 during practice?)
Non-event
(Anyway, who flies over the top of the 313 believing the Reds would never break FL95 during practice?)
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PMA
If I undestand you correctly, you are suggesting that a high-energy manoeuvre from low level can trigger a TCAS alert in an overflying aircraft because the FJ has (transiently) a RoC that the airliner's TCAS interprets as a collision threat.
If that is the problem (and I freely admit I don't really understand - the helo I fly doesn't have TCAS and has no hope of achieving the RoC needed), then I suggest we the military may need to think seriously about it. Setting off TCAS will, I understand, cause civ pilots to take evasive action, and it won't be long before the shaken passengers and the ATC who have to sort the resulting confusion start complaining hard.
Anyone out there got accurate technical info?
Sven
If I undestand you correctly, you are suggesting that a high-energy manoeuvre from low level can trigger a TCAS alert in an overflying aircraft because the FJ has (transiently) a RoC that the airliner's TCAS interprets as a collision threat.
If that is the problem (and I freely admit I don't really understand - the helo I fly doesn't have TCAS and has no hope of achieving the RoC needed), then I suggest we the military may need to think seriously about it. Setting off TCAS will, I understand, cause civ pilots to take evasive action, and it won't be long before the shaken passengers and the ATC who have to sort the resulting confusion start complaining hard.
Anyone out there got accurate technical info?
Sven
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Ooooh, I suspect there are a few issues here. Firstly, I understand that a ROC/ROD in excess of about 8000ft/min will 'confuse' TCAS. Secondly, there must be a question about the ability of the airborne systems in the conflicting aircraft(altimeter/transponder etc) to keep-up with a high ROC/ROD. If these are transmitting false or out-of-date data, then the TCAS will be presenting a resolution based on old information. Furthermore, under such circumstances, the Mode C data may well drop out thus rendering TCAS useless (in the RA sense).
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TCAS was designed by Honeywell (I think) for use primarily in the controlled/regulated airspace environment. Obviously it works just as well away from that but is limited in its algortihms (IP of the maufacturer) in its reactions to conflicts. Can't say I've ever seen an RA from high RoC/D, but have seen quite a few TA's.
Even large ac operators (ie airlines etc) should maintain VS within 500-1500fpm within 1000' of levelling off to prevent a false advisory to ac above and below. I'll stand to be corrected on those figures - has been a while!
The upshot is that TCAS is very useful in the open FIR - but only as another tool in the box - no excuses for not looking out of the window (damn that's the qfi in me)
However, having flown with it, you never want to go back to the old days. Also of interest however is the usage of GPS in accuracy of navigation - ie being so good, we all fly in exactly the same bit of airspace rather than the slight random scatter VOR and the old INS's gave.
Even large ac operators (ie airlines etc) should maintain VS within 500-1500fpm within 1000' of levelling off to prevent a false advisory to ac above and below. I'll stand to be corrected on those figures - has been a while!
The upshot is that TCAS is very useful in the open FIR - but only as another tool in the box - no excuses for not looking out of the window (damn that's the qfi in me)
However, having flown with it, you never want to go back to the old days. Also of interest however is the usage of GPS in accuracy of navigation - ie being so good, we all fly in exactly the same bit of airspace rather than the slight random scatter VOR and the old INS's gave.
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I think the TCAS spec is something along the lines of:
Prediction of less than 40secs and within 1200ft = traffic advisory
Prediction of less than 25secs and within 400ft = resolution advisory
Given that a 'high energy' aircraft could have RoC and RoD of 10000ft/min it is easy to see why aircraft flying in the proximity could have a TCAS alert even though separation is well in excess of normal VFR rules. In controlled airspace PMA 32dd is correct about the 500-1500ft RoC or RoD to prevent everyone in the hold at LHR taking avoiding action against each other. Of course the system only goes on data output and relies on accurate transmission of Mode C - if there is no altitude readout then only a TA is given. I think there was an incident (if not accident) in the far East where one aircaft was outputting an erroneous height reading and the other actually took avoiding action into its path!
I would imagine that civvies that take shortcuts to Aberdeen and Norwich etc will have a few of these TAs even though the 'offending aircraft' adheres to normal VFR avoidance rules - perhaps they just select RA mode and use the TCAS as a poor man's radar to get visual. A few spilt G&Ts over the North Sea would make top tabloid headlines and would probably result in airlines being mandated to remain within the airway structure - or perhaps encourage the CAA to establish some new airways!
Prediction of less than 40secs and within 1200ft = traffic advisory
Prediction of less than 25secs and within 400ft = resolution advisory
Given that a 'high energy' aircraft could have RoC and RoD of 10000ft/min it is easy to see why aircraft flying in the proximity could have a TCAS alert even though separation is well in excess of normal VFR rules. In controlled airspace PMA 32dd is correct about the 500-1500ft RoC or RoD to prevent everyone in the hold at LHR taking avoiding action against each other. Of course the system only goes on data output and relies on accurate transmission of Mode C - if there is no altitude readout then only a TA is given. I think there was an incident (if not accident) in the far East where one aircaft was outputting an erroneous height reading and the other actually took avoiding action into its path!
I would imagine that civvies that take shortcuts to Aberdeen and Norwich etc will have a few of these TAs even though the 'offending aircraft' adheres to normal VFR avoidance rules - perhaps they just select RA mode and use the TCAS as a poor man's radar to get visual. A few spilt G&Ts over the North Sea would make top tabloid headlines and would probably result in airlines being mandated to remain within the airway structure - or perhaps encourage the CAA to establish some new airways!
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Soiled Glove could you explain a little more please on what you mean by short cuts to Norwich and Aberdeen for example? With no airway the concept of a short cut is not apparent.
Thanks
WH
Thanks
WH
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WH,
I believe that it is a known fact that several of the 'smaller' airlines would regularly 'cut the corner' eg go direct from Newcastle to Aberdeen rather than take the airway route that goes inland and West of Edinburgh (sorry I don't know the airways designators). These aircraft would often fly through the Air Defence areas East of Leuchars/Leeming presumably on a VFR flightpath. On several occasions I have heard of F3s having to terminate an intercept due to 'stranger traffic' flying through the intercept - these 'stranger aircraft' were cutting the corner to save gas and time. The fighter controllers would generally keep the F3s away to prevent incidents - personally I would have thought it preferable to dust them off and force them back into the airways! See and be seen is fine in uncontrolled airspace when you can manoeuvre, but expecting to fly through military training airspace and then file an airprox/airmiss is in my view unacceptable, coupled with poor airmanship.
To summarise, one incident I am aware of, was a civilian aircraft flying en route to Aberdeen routing straight through a Notam'd 4v4 NVG lights out intercept - you can't see aircraft without lights at night even if it is wide open VFR and I know for a fact that very few civilian aircraft are fitted with NVGs!
SG
I believe that it is a known fact that several of the 'smaller' airlines would regularly 'cut the corner' eg go direct from Newcastle to Aberdeen rather than take the airway route that goes inland and West of Edinburgh (sorry I don't know the airways designators). These aircraft would often fly through the Air Defence areas East of Leuchars/Leeming presumably on a VFR flightpath. On several occasions I have heard of F3s having to terminate an intercept due to 'stranger traffic' flying through the intercept - these 'stranger aircraft' were cutting the corner to save gas and time. The fighter controllers would generally keep the F3s away to prevent incidents - personally I would have thought it preferable to dust them off and force them back into the airways! See and be seen is fine in uncontrolled airspace when you can manoeuvre, but expecting to fly through military training airspace and then file an airprox/airmiss is in my view unacceptable, coupled with poor airmanship.
To summarise, one incident I am aware of, was a civilian aircraft flying en route to Aberdeen routing straight through a Notam'd 4v4 NVG lights out intercept - you can't see aircraft without lights at night even if it is wide open VFR and I know for a fact that very few civilian aircraft are fitted with NVGs!
SG
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Rumour has it that recently an airliner had a 'false' TCAS warning after it was triggered by a number of red aircraft spilling out of the top of R313? Perhaps the civvies need a TCAS filter to ignore formations of more than 4 aircraft?
(* delete as appropriate)
Soiled Glove
Sorry to disappoint you but such airspace does not exist in the area to which you refer. The civilian operator in question has as much right to operate in that airspace as you do. It is encumbent on ALL users of class G to give due regard to other users of that airspace.
As an aside, if you take the attitude that "well they should not be there so stuff em" and fly close to those aircraft, rather than giving them a wide berth, the TCAS and Airprox reports will increase, which in turn will strengthen the Airline Operator's argument for more Controlled Airspace. This will mean that you will have to find somewhere else to conduct your GCI!
but expecting to fly through military training airspace and then file an airprox/airmiss is in my view unacceptable, coupled with poor airmanship
As an aside, if you take the attitude that "well they should not be there so stuff em" and fly close to those aircraft, rather than giving them a wide berth, the TCAS and Airprox reports will increase, which in turn will strengthen the Airline Operator's argument for more Controlled Airspace. This will mean that you will have to find somewhere else to conduct your GCI!
A few high speed min sep passes out over the North Sea will soon encourage Class G airline chancers to get back into their airways........
Allegedly.
No, of course I'm not being serious. But the number of J31s etc which refused point blank to cooperate with coordination requests on their directs to Woolsington used to cause a lot of grief to AD crews.
And yes, we certainly did mistakenly intercept the Norwich flyer quite a few times in pre-grunt Wattisham F4 days.
Allegedly.
No, of course I'm not being serious. But the number of J31s etc which refused point blank to cooperate with coordination requests on their directs to Woolsington used to cause a lot of grief to AD crews.
And yes, we certainly did mistakenly intercept the Norwich flyer quite a few times in pre-grunt Wattisham F4 days.
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Widger,
If you want to have a credible RAF then they have to have somewhere to train that is not affected by civilian aircraft trying to save a few pounds/seconds. By terminating a 4v4 exercise to avoid triggering a civvy TCAS costs several tonnes of fuel - imagine asking AN Other airline to burn 8 tonnes of fuel to hold while the RAF finish their training. The airways exist for a reason and while all users should use Class G airspace in a sensible manner, once again it is the military that suck the hind tit in these scenarios. More TCAS and airprox warnings might make the general public aware of how theses airlines like to 'mix it up' with the military.
SG
If you want to have a credible RAF then they have to have somewhere to train that is not affected by civilian aircraft trying to save a few pounds/seconds. By terminating a 4v4 exercise to avoid triggering a civvy TCAS costs several tonnes of fuel - imagine asking AN Other airline to burn 8 tonnes of fuel to hold while the RAF finish their training. The airways exist for a reason and while all users should use Class G airspace in a sensible manner, once again it is the military that suck the hind tit in these scenarios. More TCAS and airprox warnings might make the general public aware of how theses airlines like to 'mix it up' with the military.
SG
Soiled,
I am on your side, believe me. The trouble is, your argument will not wash. It is the military that will lose out. The flip side of your argument is the vast areas of the North Sea that you have at your disposal, that civvies have to route around, spending 1000's of pounds flying around them.
If the military wish to conduct 4v4 outside of these danger areas, then you must give due regard to everyone else.
If Airproxes/TCAS increase it will only be the military that suffer. Witness P18, wasn't there before was it? It is encumbent on all of you to minimise any occurences, because the natural conclusion will be to banish such exercises to Danger areas.
You will not stop the growth of civil traffic.
I am on your side, believe me. The trouble is, your argument will not wash. It is the military that will lose out. The flip side of your argument is the vast areas of the North Sea that you have at your disposal, that civvies have to route around, spending 1000's of pounds flying around them.
If the military wish to conduct 4v4 outside of these danger areas, then you must give due regard to everyone else.
If Airproxes/TCAS increase it will only be the military that suffer. Witness P18, wasn't there before was it? It is encumbent on all of you to minimise any occurences, because the natural conclusion will be to banish such exercises to Danger areas.
You will not stop the growth of civil traffic.
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Widger,
Just venting my frustration at the system - I know that the civilian side will win eventually and there will be more transits to far-flung corners of the the North Sea and more detachments to Goose Bay etc - but even that 'vast' area is at the whim of the North Atlantic traffic.
We've taken this slightly off topic - TCAS does it need a mod? No, it is a great system in the right airspace.
As for CWS on a 4-ship of GR4s at low level - that's another question!
SG
Just venting my frustration at the system - I know that the civilian side will win eventually and there will be more transits to far-flung corners of the the North Sea and more detachments to Goose Bay etc - but even that 'vast' area is at the whim of the North Atlantic traffic.
We've taken this slightly off topic - TCAS does it need a mod? No, it is a great system in the right airspace.
As for CWS on a 4-ship of GR4s at low level - that's another question!
SG
Class G
I agree it is for the use of everyone.
Two points though.
1. If you have a trunk full of paying passengers, how do you think they would feel if they were told they're playing dodgems with a load of mil aircraft.
2. Fly where the hell you like, just don't bitch and whine when your fancy TCAS wonder device keeps warning you of other aircraft (who, by the way, probably knew you were there before you did!)
It's called common sense or airmanship or something.
BV
Two points though.
1. If you have a trunk full of paying passengers, how do you think they would feel if they were told they're playing dodgems with a load of mil aircraft.
2. Fly where the hell you like, just don't bitch and whine when your fancy TCAS wonder device keeps warning you of other aircraft (who, by the way, probably knew you were there before you did!)
It's called common sense or airmanship or something.
BV
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(Anyway, who flies over the top of the 313 believing the Reds would never break FL95 during practice?)
And don't claim that's poor airmanship, it's why we have limits - I should suggest that avoiding such an area by 1000' vertically is the common sense approach, thereby giving the 1000' separation that is standard 'sanctuary' criteria in a military deconfliction.
ps. I wasn't muck raking, just poking fun ...
On several occasions I have heard of F3s having to terminate an intercept due to 'stranger traffic' flying through the intercept
