The "GA" TCAS systems e.g. the Avidyne 600 work just fine.

They give useless readings from Mode A transponders because there is no altitude information.

But in the circuit, the information is presented OK, and is usable if everybody is transponding Mode C/S.

I've for some time been tempted to get the system but it's about £15k (plus or minus 5k depending whether G or N reg, which avionics shop you use, and whether you free issue parts bought from the USA) and the biggest problem is that existing antennae need relocating and that makes the installation into a very large job requiring the removal of the entire aircraft interior, and not many avionics shops can do a neat job of that on a TB20.

And here is a large part of the grey area that needs to be clarified.

RIP Jimbo, will have that drink on you!

TCAS works just fine in the circuit particularly if you can display the traffic on an MDF. However, as has been commented, the aircraft must be transponding. In my experience even with mode A its a great benefit although of course there is no height information.

Not a comment on this dreadful accident but a response to the earlier post.

"Proper" TCAS, and associated RAs etc. are not really designed for Circuit type operations... hence why they disable themselves below ~1000R, and in turn need a Rad Alt fitted (more cost for GA :( ). They cause problems with parallel approaches, hindering the whole ATC idea/system... They also need each aircraft's performance programmed in...

So we now get reduced to TAs, and/or the screen display... and just encourage everybody to fly around eyes in trying to do ATCs job for them :{

GPS is part of the problem, with everybody now flying eyes in following the damn thing - whereas if they actually had to look out for features etc. and navigate, they might notice the odd other aircraft around ;) I instruct on JPs, and it is truly frightning to see someone eyes in at 200K+ "progrmaming" the thing :{

None of the above is intended to relate to Sunday's events, which the AAIB, and the AAIB alone, are fit to declare lessons to be learnt from :D

NoD

IO540: I'd venture that it's not just when they're given for a good reason that you should follow them. You should follow them because the ATCO expects that you will follow them and will have developed his plan on that basis. So if you think they're bad instructions you should tell the ATCO straight away that you intend to do something else. That's why you will frequently hear ATCOs saying things like "report if you wish to do X" because they recognise you have the freedom to do that but they want to make sure they're kept in the loop.

NB no suggestion being made here that any of this happened at Coventry last weekend.

NS

They would be wrong to disagree I'm afraid. This is not a gray area, but is actually very clear. It appears in MATS, though I don't have the time right now to look it up again.

There is a proviso though, and that's "Unless you tell them that you are not going to comply."

An ATC'er can expect you to comply with his instruction/requests in class G airspace, unless you tell him that you will not. You are under no obligation to comply with such instructions, but you are under an obligation to tell them if you will not comply.

I suppose this is simply to avoid an ATC'er telling someone to climb to 3000ft, the pilot acknowledging it, but thinking "!!!! him. I'm in uncontrolled airspace and staying at 2000ft" ,while the controller (not unreasonably) thinks that you are complying with his instruction/request.

We have discussed this before, and the appropriate references to the part in MATS has been provided.

dp

I normally rent aeroplanes with a Traffic info system in the USA and in the circuit it can be invaluable. Last time I was over we were in the circuit with about 4 other aeroplanes with a turboprop joining on the 45, parallel runway operations and aeroplanes coming in on an ILS for an intersecting runway. Scary place to be, even with traffic but at least we could see where everyone was despite the late afternoon sunshine and the mist, which made vis a nightmare.

I'm sure it did save our bacon once though. Same airport and we were departing straight out from a LH runway. ATC cleared a plane that had just departed from the RH runway for a "left departure". It was night time and we heard this and so were watching the lights, but of course it is difficult to see what is going on and where the other plane is going until it gets rather close. Suddenly we get a traffic alert, and so we stopped our climb and even started to decend and the other aeroplane went over the top of us at less than 100'. We were non too happy about this of course, but the controller was very apologetic claiming he thought the other aeroplane was higher.......

But for the grace of traffic-alert-systems.

The above is not applicable to any current GA (piston type aircraft) system.

Nonsense. GPS frees up one's attention span to look outside.
You should send them on some training, so they can manage their aviation tasks correctly.

There's a terminology issue here, I believe. This is how I understand this grey area to work (but I am as fallible as anyone else):

- An ATC unit cannot issue you with an INSTRUCTION in class G, as that would mean that you would be obliged to always obey, which clearly you can't if you are in charge of your own navigation under VFR.

- An ATC unit can issue you with a REQUEST in class G, which you are obliged to acknowledge. You are free to accept or decline such a request, but you should not just ignore it, as has already been pointed out.

It seem that this principle is generally poorly understood, which in itself is worrying. I've long felt that the growing complexity of the rules framework that we operate in is to blame for this - it's unreasonable to expect any of us to fully understand the plethora of rules upon rules upon rules that we now have.

VP

"Non proper" TCAS with a MDF works just fine in the circuit because it does not switch itself off unless you tell it to. Its a great aid combined with the mark 1 eyeball for picking up circuit traffic. In fact it also works fine for traffic with only mode A because whilst it does not give you a height the diamond is enough to give you a heads up where the traffic is and where it is going relative to you. The automatic alert "traffic, traffic, traffic" gets your attention if you have missed something for whatever reason. It is not perfect, but it is a great help.

I had an occasion recently where traffic appeared on the screen almost exactly paralelling my track and at almost the same speed. It was all too easy to imagine it was a false return. We looked for the traffic in not the best of vis. - neither of us could see it. Our tracks were very slowly converging. Sure enough, it was there, but we could not believe how late we spotted the traffic. A bit of vigorous wing waggling was not enough to grab the other pilots attention.

I recall another occasion down mig alley. The traffic was not working any of the service providers but unervingly almost exactly paralleled our course just holding off on the starboard side. We knew it wasnt working air traffic because in the end we got the jitters because we could not see it and asked if they were receiving a return and working with him. They confirmed they had a contact on radar although occasionally intermittent but were not working the traffic. We never did see that traffic.

Many years ago I was in the hold in IMC - popped out for a brief moment and there was a Warrior coming straight at me. That gave me one hell of a fright. I got a verbal apology from the controller back on the ground who was working us both and who was aware the Warrior had passed straight through the hold at same level as me. I wish I had had TCAS or PCAS then.

The trouble with PCAS, and even TCAS to a degree, is there could be a temptation not to believe it, which is why I have related these experiences. Need less to say believe it every time, even if it subsequently proves to have been wrong. I have only had a few readings that were almost certainly false whilst using PCAS.

I know most of us are not lucky enough to have TCAS but it is well worth the cost and failing that PCAS is a few hundreds of pounds and still pretty good.

There are those that might say it encourages you to keep your head in the cockpit. They would be wrong. If you wish ignore the PFD, ignore the PCAS display, maintain your visual scan - there is no need to look at either. While your eyes are busy outside or with the task in hand the audible alarm will instantly grab your attention, a quick glance at the screen and you know where you should be looking in that moment.

This whole incident has convinced me to buy a Zaon PCAS device and interface it to my G496. Seems like $1700 is a good insurance policy, and HAD I been the "other" aeroplane in this sad incident, it would probably have worked quite well (i.e. all commercial twins will have Mode S).

If you look at: WebTrak: Bournemouth and choose 11:45 on 28th July and look to the top left (near Blandford, may have to zoom out or move map) there are two aeroplanes, one transponding 7370 which come pretty close. 7370 was me, and despite what the altitude readouts say we were pretty much at the same level. We didn't see each other until it was pretty close, and he saw me before I saw him....it was a "whites of the eyes" moment.....

Re terminology, have got to disagree. Regardless of whether ATC pass an instruction or a request to you in Class G, it would be gross bad airmanship to not acknowledge.

???????

I didn't even hint at "not acknowledging" any radio transmission in my post on terminology, so where did that idea come from? Did you actually bother to read and understand what I wrote before posting your disagreement with it?


Mind you, if I was flying non-radio (which I do a fair bit of the time, for purely practical reasons associated with having no electrical power) then I wouldn't know that any ATC unit was trying to talk to me, and wouldn't be able to acknowledge any call. Of course, I'd question the wisdom of flying non-radio in an area as dodgy as this, but it would be perfectly legitimate, if very unwise IMHO.

VP

Ok, have a bit more time now to look up the reference.

It's from MATS part 1, Section 3, Chapter 1 "Approach Control"

Hopefully that remove some of the gray ;)

dp

As a former employee of Atlantic in OPS, I would like to pass on my condolences to those who are no longer with us and their families.


SG,HA,JB.... my thoughts are with you always

R.I.P

JAS

Back to the real subject: thoughts and sincere condolences to the families and friends of the five Aviation people involved in this tragic accident.

Yorky Towers

Keep flying Jimbo...I'm sure many pints will be risen in celebration and remembrance! Your memory will live on at WW and I'm sure at Coventry as well.

My condolences to the rest of those involved.

RCW

“I'd question the wisdom of flying non-radio in an area as dodgy as this, but it would be perfectly legitimate”

Lots of non radio aircraft based in the area. This includes Micros, LAA and Gliders from multiple strips and airfields. However, I would have thought that non would be at 900ft 3nm for Cov. I following the last fatal mid air I did an analysis of the aircraft in my vicinity (10 min flying time north of this incident) and concluded that 80% would not be transponder equipped.

Rod1

Says the bloke who admitted flying non-radio 'a fair bit of the time'.
What exactly is this 'dodgy' bit your talking about. It's Class G airspace, you don't have to be equipped with a radio. If the CAA started telling the flying fraternity that they had to be radio equipped regardless of a/c type and airspace used, the noise would be deafening, it'd sound like a slaughterhouse on porky pig day! Why don't you email that comment to the BGA and see what response you get.
The airspace round Cov isn't dodgy, it's just Class G, there's a difference.