Tcas
Re: Tcas
My point about the METS graduates is that it seems that CFS have invented yet another thing to talk about whilst flying. I think it is totally unnecessary for crews to comment on a blank TCAS display before manouvreing and it is incorrect to modify manoeuvres in the lateral plane purely based on TCAS information. So why mention it? - unless it has picked up a contact that you are trying to aquire visually. Apologies to the CFS guys if this is not of their doing, but some of their recent graduates have got this habit from somewhere. Maybe it's part of the "I must commentate on everything I do or think in order to impress you" strategy that the trg system seems to produce.
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Re: Tcas
Wile I think that any device that can help to avoid a collision is a good thing and I understand that in military aviation RA commands are not a good idea I cant help thinking that the big picture has been missed.
In the USA traffic information can be data linked via the mode S transponder from ATC ground radar giving the pilot a "near TCAS" system that seems to do all that the system fitted to the Tucano will do but at a fraction of the cost of the device fitted to the Tucano. The only problem is getting NATS to enable the system.
It would seem to me that if the ground station part of this system could be put on line the low cost of the aircraft equipment would encourage the MOD to fit it to more of the military fleet, the cost is within the budget of even the lower end of the IFR equiped private aircraft fleet.
Having most of the aircraft flying in class G airspace equiped with a collision avoidence system should be a goal of the CAA and MOD it would make flying safer for both the civil and military pilots and in the long run must save all airspace users money.
The bonus with the system is that it can also be linked to ground weather radar giving weather avoidance information to aircraft that can't be fitted with weather radar.
It is time for the military and civil airspace users to get together for the common good and press NATS and Eurocontrol into enableing this system.
www3.bendixking.com/servlet/com.honeywell.aes.utility.PDFDownLoadServlet?FileName=/static/brochures/pdf/KMH%20880%20KTA%20870.pdf
In the USA traffic information can be data linked via the mode S transponder from ATC ground radar giving the pilot a "near TCAS" system that seems to do all that the system fitted to the Tucano will do but at a fraction of the cost of the device fitted to the Tucano. The only problem is getting NATS to enable the system.
It would seem to me that if the ground station part of this system could be put on line the low cost of the aircraft equipment would encourage the MOD to fit it to more of the military fleet, the cost is within the budget of even the lower end of the IFR equiped private aircraft fleet.
Having most of the aircraft flying in class G airspace equiped with a collision avoidence system should be a goal of the CAA and MOD it would make flying safer for both the civil and military pilots and in the long run must save all airspace users money.
The bonus with the system is that it can also be linked to ground weather radar giving weather avoidance information to aircraft that can't be fitted with weather radar.
It is time for the military and civil airspace users to get together for the common good and press NATS and Eurocontrol into enableing this system.
www3.bendixking.com/servlet/com.honeywell.aes.utility.PDFDownLoadServlet?FileName=/static/brochures/pdf/KMH%20880%20KTA%20870.pdf
Last edited by A and C; 15th Jan 2006 at 19:08.
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Re: Tcas
There seems to be a great deal of misunderstanding about TCAS and some scepticism from those who have never had the opportunity to fly with it.
Over the last 7 years I have been flying TCAS equipped aircraft for my bread and butter, mainly in class G airspace. The equipment we operate does NOT give RAs, only TAs. It is not linked to the radalt.
Simply put, the equipment transmits, just like an ATC secondary radar, and picks up transponder returns which are displayed on the circular screen. The airspace display can be "zoomed" in or out in stages, as the pilot sees fit. In the case of the present aircraft I fly, the displayed range can be set from 40 nautical miles to 3 miles. I normally fly with it set at 10 nm or 15 nm by preference, depending on the circumstances.
If a "Mode C" return is picked up, a diamond dot appears with relative altitude figures alongside. For example, "00" means same altitude and "+05" means 500 feet above or "-03" means 300 feet below. An up or down arrow alongside that figure means the traffic is climbing or descending respectively. As the "Mode C" altitude figures are based on information from a coding altimeter, they are generally very accurate.
If a "Mode A" only return is picked up, the relative altitude figures are absent and only a diamond dot appears on the screen. These are the worrying ones, such a target could be 2700 feet above or below the aircraft, the TCAS can't tell.
Relative azimuth information is computed and isn't as reliable as the altitude information. For example, an aircraft actually directly ahead could be shown as slightly left or right of the nose, or it may oscillate from left to right across the nose. If the TCAS decides there is a possibility of aircraft paths crossing based on "Mode A" azimuth information alone, it plays safe and gives a TA alert. These can be very worrying at the time, the supposedly conflicting aircraft could be out of sight above or below; natural survival instinct means that the pilot's eyes are generally out on stalks at this stage.
A TA comes in the from of a (loud) digital voice input to the pilot's intercom: "TRAFFIC, TRAFFIC!"
It is up to the pilot to hear the warning (not difficult!) interpret the displayed information and to carry out avoiding action if necessary. It might or might not be necessary and is preferably done after visually acquiring the opposing traffic, NOT by looking at the dial in isolation. In IMC height separation is safest, due to the limitations of azimuth accuracy.
The use of TCAS whilst flying at 250 feet shouldn't give any problems as far as I can see; it certainly didn't when I flew a police helicopter.
Over the last 7 years I have been flying TCAS equipped aircraft for my bread and butter, mainly in class G airspace. The equipment we operate does NOT give RAs, only TAs. It is not linked to the radalt.
Simply put, the equipment transmits, just like an ATC secondary radar, and picks up transponder returns which are displayed on the circular screen. The airspace display can be "zoomed" in or out in stages, as the pilot sees fit. In the case of the present aircraft I fly, the displayed range can be set from 40 nautical miles to 3 miles. I normally fly with it set at 10 nm or 15 nm by preference, depending on the circumstances.
If a "Mode C" return is picked up, a diamond dot appears with relative altitude figures alongside. For example, "00" means same altitude and "+05" means 500 feet above or "-03" means 300 feet below. An up or down arrow alongside that figure means the traffic is climbing or descending respectively. As the "Mode C" altitude figures are based on information from a coding altimeter, they are generally very accurate.
If a "Mode A" only return is picked up, the relative altitude figures are absent and only a diamond dot appears on the screen. These are the worrying ones, such a target could be 2700 feet above or below the aircraft, the TCAS can't tell.
Relative azimuth information is computed and isn't as reliable as the altitude information. For example, an aircraft actually directly ahead could be shown as slightly left or right of the nose, or it may oscillate from left to right across the nose. If the TCAS decides there is a possibility of aircraft paths crossing based on "Mode A" azimuth information alone, it plays safe and gives a TA alert. These can be very worrying at the time, the supposedly conflicting aircraft could be out of sight above or below; natural survival instinct means that the pilot's eyes are generally out on stalks at this stage.
A TA comes in the from of a (loud) digital voice input to the pilot's intercom: "TRAFFIC, TRAFFIC!"
It is up to the pilot to hear the warning (not difficult!) interpret the displayed information and to carry out avoiding action if necessary. It might or might not be necessary and is preferably done after visually acquiring the opposing traffic, NOT by looking at the dial in isolation. In IMC height separation is safest, due to the limitations of azimuth accuracy.
The use of TCAS whilst flying at 250 feet shouldn't give any problems as far as I can see; it certainly didn't when I flew a police helicopter.
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Re: Tcas
One thing that the TCAS user must be aware of is that the azimuth information is not particularly accurate (as intimated by shy tourque) and certainly not up to the required standard for ATC radar separation purposes.
The amount of professional airliner pilots who try to second guess ATC by saying they have the traffic on TCAS, and requesting further climb/descend as a result is ridiculous.
I hope that the students are taught how to use it properly and are fully informed of its limitations - it is a very good tool when used properly for what it is designed for. It does not replace the mark 1 eyeball, it augments it.
The amount of professional airliner pilots who try to second guess ATC by saying they have the traffic on TCAS, and requesting further climb/descend as a result is ridiculous.
I hope that the students are taught how to use it properly and are fully informed of its limitations - it is a very good tool when used properly for what it is designed for. It does not replace the mark 1 eyeball, it augments it.
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Re: Tcas
Some respondants have been quick to criticise others who have posted... many will not have flown with TCAS, or ar ATCO's etc... so are asking questions to broaden their understanding, not necessarily being critical or dismissive?
Shytorgue says if a Mode A only response is detected the contact may be 2700 above or below... how does the system know, without Mode C to help, that it is not outside that band?
Shytorgue says if a Mode A only response is detected the contact may be 2700 above or below... how does the system know, without Mode C to help, that it is not outside that band?
Re: Tcas
As far as I'm aware, non-altitude reporting SSR-equipped traffic will be assumed to be co-altitude and will, if their closest point of approach is predicted to enter the traffic advisory sector, cause a TA to be issued.
ukatco_535 is absolutely correct with what he states - you must not rely upon TCAS bearing information as it is highly inaccurate. Neither must those using the very basic Tucano system belive that it is anything like as comprehensive as ACAS II used by commercial aircraft.
ShyTorque's figure of 2700ft above or below comes from the ability of some TCAS displays to be switched to display only traffic which is either within the altitude band of 2700 ft above or below the aircraft in 'normal' mode, 8700 ft above to 2700 ft below in 'above' mode or 2700 ft above to 8700 ft below in 'below' mode as determined by Mode C or Mode S altitude. As any non-altitude reporting aircraft are assumed to be co-altitude, they will be therefore be displayed as being within the 2700 ft above or below area in 'normal' mode even if actually well outside that as the system cannot determine their actual altitude.
Most, but by no means all, GA puddlejumpers not receiving an ATC service will routinely squawk 7000C if so equipped - but many still only have Mode A. TAs based on Mode A traffic could well prove a huge distraction in some parts of the UK to pilots using TCAS in Class G airspace. An environment for which TCAS was never intended! And don't forget that carriage of even Mode A is still not mandatory for most VFR GA traffic in Class G airspace.......
ukatco_535 is absolutely correct with what he states - you must not rely upon TCAS bearing information as it is highly inaccurate. Neither must those using the very basic Tucano system belive that it is anything like as comprehensive as ACAS II used by commercial aircraft.
ShyTorque's figure of 2700ft above or below comes from the ability of some TCAS displays to be switched to display only traffic which is either within the altitude band of 2700 ft above or below the aircraft in 'normal' mode, 8700 ft above to 2700 ft below in 'above' mode or 2700 ft above to 8700 ft below in 'below' mode as determined by Mode C or Mode S altitude. As any non-altitude reporting aircraft are assumed to be co-altitude, they will be therefore be displayed as being within the 2700 ft above or below area in 'normal' mode even if actually well outside that as the system cannot determine their actual altitude.
Most, but by no means all, GA puddlejumpers not receiving an ATC service will routinely squawk 7000C if so equipped - but many still only have Mode A. TAs based on Mode A traffic could well prove a huge distraction in some parts of the UK to pilots using TCAS in Class G airspace. An environment for which TCAS was never intended! And don't forget that carriage of even Mode A is still not mandatory for most VFR GA traffic in Class G airspace.......
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Re: Tcas
BEagle... thank you for expanding somewhat on this subject, and rasing some interesting and valid points... one addition on the subject of 7000 squawks is that the Mode C from such aircraft is unverified and, although unlikely, may be incorrect. This may give a false sense of safety and encourage the pilot to discount the contact (as discussed elsewhere on this forum). Keep your eyes open and in Class G use TCAS as a tool to prevent collisions not maintain separation, a subtle but important difference.
Re: Tcas
The "verification" of Mode C readouts by ATC SSR is to allow them to reduce lateral seperation. An RA issued by TCAS will be followed regardless of the existence of any verification of the intruders Mode C by ATC. I wholeheartedly agree that lookout is still of overriding importance in Class G airspace. However, I think that it is just as pertinent not to assume that the traffic that you have spotted is actually the contact that TCAS is worried about - which opens up a another whole debate about switching to TA to avoid "nuisance" RAs, particularly in the circuit.
Our TCAS scans +/- 9000 feet and the Above/Below/Normal switch simply declutters the presentation as per the bands described by BEAgle. A squawk that is outside the current band will still trigger a TA or (less likely) an RA if TCAS regards it as a threat - Eg a FJ with a high rate of climb. Non mode C squawks are regarded as co-level and can trigger a TA even if they are 9000 feet below - the lack of Mode C prevents TCAS from screening them out. When military radar say "No Height" do they mean no verified mode C? I would rather be told "..indicating FLxx unverified" so that at least I know to which TCAS contact ATC are referring (probably). Furthermore, I can see no value whatsoever in responding to ATC traffic information with "Got it on TCAS" as there can be no resulting reduction in seperation.
Our TCAS scans +/- 9000 feet and the Above/Below/Normal switch simply declutters the presentation as per the bands described by BEAgle. A squawk that is outside the current band will still trigger a TA or (less likely) an RA if TCAS regards it as a threat - Eg a FJ with a high rate of climb. Non mode C squawks are regarded as co-level and can trigger a TA even if they are 9000 feet below - the lack of Mode C prevents TCAS from screening them out. When military radar say "No Height" do they mean no verified mode C? I would rather be told "..indicating FLxx unverified" so that at least I know to which TCAS contact ATC are referring (probably). Furthermore, I can see no value whatsoever in responding to ATC traffic information with "Got it on TCAS" as there can be no resulting reduction in seperation.
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Re: Tcas
The "verification" of Mode C readouts by ATC SSR is to allow them to reduce lateral seperation
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Re: Tcas
Originally Posted by Farfrompuken
Let me spell it out for you:
TA: Traffic advisory. Lets you know graphically where traffic is.
RA: Resolution advisory. Provides commands via VSI to achieve vertical separation.
Tucano system will not be linked to VSI as far as I know; it appears to be a standalone dispay. Therefore, It won't be capable of RA. Even if it were, you could select TA mode to avoid nuiscance alerts (e.g. in circuit etc....).
TA: Traffic advisory. Lets you know graphically where traffic is.
RA: Resolution advisory. Provides commands via VSI to achieve vertical separation.
Tucano system will not be linked to VSI as far as I know; it appears to be a standalone dispay. Therefore, It won't be capable of RA. Even if it were, you could select TA mode to avoid nuiscance alerts (e.g. in circuit etc....).
No expert on TCAS as you've pointed out; but I understand the difference between the two. What I was wondering was if it was possible to generate an RA without a link to the VSI. After all, the TCAS kit must make the decision as to whether climbing or descending is the best plan; so is there any reason why a bit of kit without access to the VSI couldn't suggest "climb" or "descend" in your ear as an RA?
Originally Posted by Farfrompuken
As I mentioned earlier, it is a tool to ASSIST lookout, not replace it. YOU WILL NOT BE FLYING ALONG STARING AT THE FISHFINDER UNLESS YOU ARE TOTALLY STUPID.
The flight regimes that the Tucano operates in at med level will be where it benefits the most (microlites et al no squawking lower down etc).
Wait till you've got a tad of time on the kit, then by all means let us know what you think, but to comment with no knowledge is a tad churlish
The flight regimes that the Tucano operates in at med level will be where it benefits the most (microlites et al no squawking lower down etc).
Wait till you've got a tad of time on the kit, then by all means let us know what you think, but to comment with no knowledge is a tad churlish
He may think he just has to do a few token head moves, because TCAS will show him when he has to look, and where. The system's not perfect, after all.
Re: Tcas
Pierre, Understood about verification.
However, I will always follow a TCAS RA regardless of the Mode C verification . The TCAS RA assumes priority over ATC instructions and clearances. The chance of the Mode C being wrong is much smaller than the risk of collision if the RA is not followed. I accept that 7000 Squawks in the UK are unverified, but so are squawks in procedurally controlled airspace. In the recent airprox involoving Hawks v Airliner, the airliner would have manoeuvred to follow any RA issued if the Hawk's IFF had not failed - unverified or not.
I hope this topic has highlighted importance of squawking mode C if you are at all able, even whilst not talking to ATC. As a TCAS user, often in Class G airspace, I wish that everyone would squawk mode C at all times and that a Mode C transpnder was mandatory for all aircraft. I know the GA communtiy would object, but I would feel safer.
I am amazed that any money has been found for TCAS on Tucano though. Every new bit of kit I have seen has been due to legislation changes or UORs. For years our pax carrying ac touted a military exemption from TCAS. We didn't even change our position after the USAF and Luftwaffe had a random mid air between 2 transport aircraft over West Africa (C141 v Tu154) which prompted them to fit TCAS to their large ac. It was always going to take a crash or a rule change for us to see TCAS. Fortunately the Germans said no TCAS, no-entry as of Jan 05 and we were duly equipped.
Ultimately it is a great bit of kit and I would hate to go back to flying without it. Now what about EGPWS!
However, I will always follow a TCAS RA regardless of the Mode C verification . The TCAS RA assumes priority over ATC instructions and clearances. The chance of the Mode C being wrong is much smaller than the risk of collision if the RA is not followed. I accept that 7000 Squawks in the UK are unverified, but so are squawks in procedurally controlled airspace. In the recent airprox involoving Hawks v Airliner, the airliner would have manoeuvred to follow any RA issued if the Hawk's IFF had not failed - unverified or not.
I hope this topic has highlighted importance of squawking mode C if you are at all able, even whilst not talking to ATC. As a TCAS user, often in Class G airspace, I wish that everyone would squawk mode C at all times and that a Mode C transpnder was mandatory for all aircraft. I know the GA communtiy would object, but I would feel safer.
I am amazed that any money has been found for TCAS on Tucano though. Every new bit of kit I have seen has been due to legislation changes or UORs. For years our pax carrying ac touted a military exemption from TCAS. We didn't even change our position after the USAF and Luftwaffe had a random mid air between 2 transport aircraft over West Africa (C141 v Tu154) which prompted them to fit TCAS to their large ac. It was always going to take a crash or a rule change for us to see TCAS. Fortunately the Germans said no TCAS, no-entry as of Jan 05 and we were duly equipped.
Ultimately it is a great bit of kit and I would hate to go back to flying without it. Now what about EGPWS!
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Re: Tcas
Brain
when the military say 'no height' they mean purely that. The aircraft has no height information (could be 7000 without Mode C or even just a primary contact)
If the height is unverified (i.e. 7000 squawk with Mode C)- they should say that it is unverified.
when the military say 'no height' they mean purely that. The aircraft has no height information (could be 7000 without Mode C or even just a primary contact)
If the height is unverified (i.e. 7000 squawk with Mode C)- they should say that it is unverified.
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Relax, Elmlea,
As the above average creamie at Linton, as I'm sure you are , you'll soon see when his flying goes to pot that he's staring at the scope too much. You'll then be able to debrief him/her accordingly.
I'm sure when they introduced such innovations as TACAN/ADF etc., QFIs like you were concerned about the effect on trainees; 'they may spend all their time staring at the HSI in a desperate attempt to navigate', but funny old thing they actually seemed to cope with such levels of input.
The average BFJT stude is more concerned about performing well on his streaming board. To that end, he/she will be trying to impress their S+L skills ccts, stalling/areos/spinning etc. which all rely on VISUAL flying.
So relax, my friend, enjoy the benefits of TCAS. Don't be a TCAS monkey as I'm sure you won't, but don't be flying around with it switched off or you'll do yourself no favours.
As the above average creamie at Linton, as I'm sure you are
, you'll soon see when his flying goes to pot that he's staring at the scope too much. You'll then be able to debrief him/her accordingly.I'm sure when they introduced such innovations as TACAN/ADF etc., QFIs like you were concerned about the effect on trainees; 'they may spend all their time staring at the HSI in a desperate attempt to navigate', but funny old thing they actually seemed to cope with such levels of input.
The average BFJT stude is more concerned about performing well on his streaming board. To that end, he/she will be trying to impress their S+L skills ccts, stalling/areos/spinning etc. which all rely on VISUAL flying.
So relax, my friend, enjoy the benefits of TCAS. Don't be a TCAS monkey as I'm sure you won't, but don't be flying around with it switched off or you'll do yourself no favours.
