TCAS for low level traffic avoidance????
Thread Starter
Joined: Apr 2004
Posts: 46
Likes: 0
From: The dark side
TCAS for low level traffic avoidance????
Hello everyone. I'm a tower controller from Ireland and I've a wee question for you.
Recently I've noticed that when i pass traffic info to VFR Helis transiting through the zone, some of them (1 in particular) replie "yeah, we have him on TCAS".
Now, I'm spending nearly all my time on the ground and even though I'm familiar with TCAS, TAs and RAs, and even though it's reliant on mode C, I'm thinking it's not exactly a surveilance radar.
So can someone tell me, is TCAS useful in a Low level VFR situation?
More to the point, Is using TCAS considered an acceptable substitute (by anyone) for having traffic in sight? (I say No)
And finally, does anyone have any further to add...
Recently I've noticed that when i pass traffic info to VFR Helis transiting through the zone, some of them (1 in particular) replie "yeah, we have him on TCAS".
Now, I'm spending nearly all my time on the ground and even though I'm familiar with TCAS, TAs and RAs, and even though it's reliant on mode C, I'm thinking it's not exactly a surveilance radar.
So can someone tell me, is TCAS useful in a Low level VFR situation?
More to the point, Is using TCAS considered an acceptable substitute (by anyone) for having traffic in sight? (I say No)
And finally, does anyone have any further to add...
Joined: Apr 2001
Posts: 496
Likes: 4
From: Norfolk
Useful, yes - very much so, but only as part of a package of collision avoidance methods such as HISLs, colour scheme and, err.. eyeball. It's obviously not a personal radar but I can see how the unwary might fall into that trap; a TCAS return is of course just a general guide where to look, especially when like us you're doing low level orbits with cameras and lights dangling in the way of the aerial. Where we operate there are modest numbers of fast jets and plenty of VFR low level stuff; it's very good for warning of those, but no use at all for the non-transponder people pootling along in the open FIR.
I would far rather have a TCAS than not, or indeed one of the lesser systems such as Skywatch, but they are a scary price for the smaller operator.
I would far rather have a TCAS than not, or indeed one of the lesser systems such as Skywatch, but they are a scary price for the smaller operator.
Joined: Aug 2000
Posts: 3,670
Likes: 1
From: UK
Saved our crew from a certain mid air in May 2004.
Fantastic piece of kit, but one has to realise that TCAS only shows up those who are transmitting....what about the rest????
From an ATC perspective, I would expect an air trafficker to treat it as a 'bolt on toy' and treat us as normal!
Fantastic piece of kit, but one has to realise that TCAS only shows up those who are transmitting....what about the rest????
From an ATC perspective, I would expect an air trafficker to treat it as a 'bolt on toy' and treat us as normal!
Avoid imitations
Joined: Nov 2000
Aviation Qualifications: ATPL
Posts: 15,110
Likes: 1,083
From: Wandering the FIR and cyberspace often at highly unsociable times
"So can someone tell me, is TCAS useful in a Low level VFR situation?
More to the point, Is using TCAS considered an acceptable substitute (by anyone) for having traffic in sight? (I say No)"
1) A definite YES!
2) A definite NO!
I have modified my lookout scan to include the TCAS screen. It is an addition to, not a replacement for lookout.
There are dangers with a TCAS!
a) A pilot might put too much reliance on the TCAS but it doesn't take much experience in using it to realise that it doesn't pick up all traffic.
b) A TCAS target on the screen might mask another aircraft not appearing in that picture due to non-squawking. i.e. two conflicting aircraft exist and the wrong (non critical) one seen and concentrated on, to the detriment of lookout. If my co-pilot spots an aircraft from the TCAS, I try to lookout and not lose my lookout scan.
More to the point, Is using TCAS considered an acceptable substitute (by anyone) for having traffic in sight? (I say No)"
1) A definite YES!
2) A definite NO!
I have modified my lookout scan to include the TCAS screen. It is an addition to, not a replacement for lookout.
There are dangers with a TCAS!
a) A pilot might put too much reliance on the TCAS but it doesn't take much experience in using it to realise that it doesn't pick up all traffic.
b) A TCAS target on the screen might mask another aircraft not appearing in that picture due to non-squawking. i.e. two conflicting aircraft exist and the wrong (non critical) one seen and concentrated on, to the detriment of lookout. If my co-pilot spots an aircraft from the TCAS, I try to lookout and not lose my lookout scan.
Joined: Nov 2004
Posts: 291
Likes: 0
From: UK
Concur with TC & ST - TCAS is excellent but it's not perfect and is only in addition to normal good lookout practice.
It's sometimes more of an "area" tool which tends (in my experience) to give an accurate distance readout but often inaccurate bearing, anything up to 90deg out sometimes - possibly due to the 20+ other aerials and metalwork hanging off the aircraft? When ATC pass traffic info, it can be useful to tie a known contact into TCAS, especially if you can see it - but important not to forget that, unless you are visual, there may well be others out there to confuse.
It's interesting to see how many contacts suddenly appear when ATC info is passed & we reply "thanks, looking, nothing on on TCAS at the moment"!
As already mentioned, it does need the other chap to transpond, of course.
It's sometimes more of an "area" tool which tends (in my experience) to give an accurate distance readout but often inaccurate bearing, anything up to 90deg out sometimes - possibly due to the 20+ other aerials and metalwork hanging off the aircraft? When ATC pass traffic info, it can be useful to tie a known contact into TCAS, especially if you can see it - but important not to forget that, unless you are visual, there may well be others out there to confuse.
It's interesting to see how many contacts suddenly appear when ATC info is passed & we reply "thanks, looking, nothing on on TCAS at the moment"!
As already mentioned, it does need the other chap to transpond, of course.
Joined: Jul 2002
Posts: 512
Likes: 0
From: Texas
I think it's an excellent tool, and should be in every cockpit. Since we got them, I see probably 5 times the traffic I did before. After seeing a target on the scope, we start concentrating on a specific area, and often see traffic we would never have seen otherwise. It is certainly not infallible, and is just another tool, mostly for use where there is no ATC. I would never assume that there is no traffic just because there is none on the scope, but I'll take all the information I can get.
Joined: Mar 2003
Posts: 573
Likes: 0
From: uk
TCAS and HISL and EYES and EARS are the aids we can use to avoid collision. It is my opinion that all the observations made previously are valid points and we all can fall into the trap of watching the instruments at the expense of 'LOOKOUT'. TCAS is a super tool with limitations. If I were an ATC controller I would be very worried about a pilot who gave a report related to what is seen on the TCAS, wouldn't you!
Joined: Apr 2003
Posts: 3,012
Likes: 1
From: USA
If I were an avionics designer I'd make TCAS III and fire all the ATC guys.
The TCAS has voice notification, nobody stares at the screen
Percent of times I have heard the TCAS say "Traffic" before I saw the target = 99%. Percent of times I have seen traffic before ATC tells me = 50%
The TCAS has voice notification, nobody stares at the screen
Percent of times I have heard the TCAS say "Traffic" before I saw the target = 99%. Percent of times I have seen traffic before ATC tells me = 50%
Joined: Aug 1999
Aviation Qualifications: ATP+Mil
Posts: 4,411
Likes: 83
From: Gold Coast, Australia
Nick,
Machine I fly with TCAS, voice, moving map & all the fruit salad seems to get the range, but the bearing stands a 50/50 chance of being vaguely right
I then spend an inordinate amount of time looking in the wrong direction, whilst Moaning Minnie keeps on "Traffic, traffic yada yada" with often multiple hits on the same Tx response.
But the mute button works
Machine I fly with TCAS, voice, moving map & all the fruit salad seems to get the range, but the bearing stands a 50/50 chance of being vaguely right
I then spend an inordinate amount of time looking in the wrong direction, whilst Moaning Minnie keeps on "Traffic, traffic yada yada" with often multiple hits on the same Tx response.But the mute button works
