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.

http://www.pprune.org/atc-issues/338294-radio-use.html

It may interest some to see the replies to the small thread re radio use I posted earlier this month on the ATC forum.
Long before this tragic accident!
Lister:)

I personally think transponder far more likely to reduce the risk of mid air collisions than radio. Radio relies on correct and accurate pilot usage to pin point their location whereas a xponder is doing the job far more accurately. Obviously this is only of relevance in certain airspace at the moment but in 2008 I think it about time we made moves to make a xponder mandatory in any part of UK airspace and to start tracing people who fail repeatedly to switch the thing on, as it's equates to suicidal laziness IMHO. Laugh if you will but there're more and more aircraft appearing on the GA market equiped with TCAS nowadays but what use is that when people don't use their xponder?

Just a few thoughts on the subject, now I shall stand back and get shot down by the farmstrip diehards who are more interested in getting away with a spot of Rule 5 breaking than avoiding the potential for a collision... cuz let's face it - they're the usual suspects when it comes to not switching their xponder on. There - I've said it!

VFE.

.

WOW VFE! And I thought I was the contentious one!!

I'll rise to the bait VFE.

Every year we kill over 3000 people on the roads - year in year out.

One unfortunate incident - the causes of which we are only speculating upon and you decide it is necessary to ground something approaching half the aircraft in the country. ('cos they cannot fit transponders).

My!

There are many words that could be used but rational and sensible are not amongst them.

For those who are using TCAS and its less functional poor cousins, are you solely using it to determine traffic in a vertical plane, or do you think it's some kind of pseudo radar giving you accurate horizontal awareness as well ?

It's a great piece of kit, but you need to understand the philosophy behind its design and the inherent innaccuracies if you use it in a different way from that intended by the manufacturers and those who specify the industry standard for ACAS devices.

A mere pup Bose-X me ole.... ;)

Ok, slight wind up aside, xponder usage and in particular the requirement to squark Mode C (if fitted) has featured in quite a few industry safety awareness publications for quite some time now yet many PPL holders can't even be bothered to switch the thing to standby and we all know why - they have this ridiculous mistaken idea that if they bust controlled airspace they won't be caught if their xponder is switched off.

VFE.

That's a worrying statement? :confused: :eek:

The "dodgy" reference was with regard to all of the comments from those blithely flying ILS approaches through this bit of class G under the false assumption that they were, in some way, protected by ATC.

Good airmanship seems to me to be more than just following the law laid down in the ANO; it would be small comfort to be greeted at the pearly gates, asked how one came to meet ones' demise and reply that it was because you followed the letter of the law.

In my case it's more to do with cowardice. I've been around long enough to get seriously worried when flying in areas that I know may be populated with people who feel that have precedence over others, when legally they don't (as far as I can see). My safety mechanism is simply not to fly in those areas if I can possibly avoid it; maybe I'm wrong, but this is just self-preservation on my part.

VP

It is truly astonishing to see how many people out there use TCAS as a panacea and who have no idea of how it really works or what it is there for.
One can even find certain "professionals" shrugging off bad practice with "He's got TCAS anyway."
Have had some very serious words with folks over here about it.

This is the best argument I have seen for the mandatory imposition of controlled airspace around every instrument approach.

We have a direct conflict of interest in GA between those who quote the fact that Class G is uncontrolled so they may do what they want and to hell with ATC, and those who look at a map, see a marked approach and consider avoiding it (or at least talk to ATC).

As far as I can see the forthcoming change to ATSOCAS will do nothing but make the situation worse.

Unfortunately it is also perfectly true. Just ask anyone from D&D. It's also not confined to PPLs, those earning their daily crust by flying have also been known to do it.

As stated here, there is an established system called "TCAS". I got slated above for a reference to it, and how it "did not apply to GA systems". Can we at least establish that "TCAS" is the "system" installed and used in large commercial aircraft, and differentiate from other systems that might assist in traffic awareness and potential collision avoidance.

As the poster above implies, TCAS is a "system" involving hardware + pilot & ATCO training and actions. It is not perfect - it has so far caused one mid-air with >100 fatalities (hardware fine, human factors and training not...) and one very near mid air (2 x widebody, all human factors fine, but 1 dodgy wire :{ ). Also for reasons various "TCAS" is not really applicable to the GA / VFR environment for many reasons.

We then come on to to various hardware solutions that do some things similar to TCAS hardware - albeit they seem to be on the TA side, not RA? It is fine for one or 2 systems (certified?) to express a "display" on where other aircraft may (or may not) be in relation to your aircraft. But if we start talking of mandating such systems? What training is required? They seem largely to revolve around Mode C? Are GA Mode C altitudes broadcast to the required accuracy for collision avoidance? As opposed to ATC separation requirements (far more tolerant). TCAS is an active system to determine range? Whereas I understand these systems largely passive? And as implied above, even though TCAS does a fair job at displaying "bearing", this is "info only" and TA/RA warnings based solely on the (accurate) range calculations? Are these systems, broadcasting "relative bearing", willing to be certitied (and accountable in a court of law) on that basis?

And if we do go down this route, what of training / the law? With TCAS, it is now 100% established that TCAS overrides ATC, and almost 100% pilot judgement as well... even if we see the "traffic", how do we really know it is the one the RA is based on? As such, we train regularly for TCAS... But in the GA environment? Is it legitimate to follow a "warning" and climb into CAS?

NoD

VFE makes the point that not using a transponder is not going to save you from being identified in the event of an airspace bust. The fact of the matter is though, that, of the four infringers of the notorious red arrows TRA ( as it then was known) Elvington bust in 2003, the only one who was actually identified and prosecuted was the hapless and responsible pilot who was actually sqawking his position (and identity). The other non squawkers got away unidentified and scot free.
The use of safety related equipment to mount prosecutions of this type is completely inappropriate. It is no wonder that pilots are apprehensive about mode S and switching the damn things on in the first place....

NigelOnDraft

Firstly, I think that the accident you refer to was one where the crew ignored their TCAS advisory and acted on ATC orders instead (and hit the other plane). So this is hardly a case of TCAS "causing" a crash.

Secondly, the altitude information fed to the TCAS in your airliner is also from a barometric source. No different to the GA systems such as this one.

The system is informational only - you don't get resolution advisories. But it does tell you about where other traffic is in both azimuth and relative altitude, so the resolution is obvious. In a head-on situation, you turn to the right, etc.

You're missing the point.

TCAS is not a box that causes things.
It is a system - involving displays, ATCOs and pilots.
TCAS did not fail during the DHL incident - the system did.
And if you re-read Nigel's post, he states that the system caused the accident - and he is correct about that.

It's not really that clean cut. And you are only quoting on a head-on situation. With no RA/TA commands, on your "TCAS" display - what would you do in a situation that was not head-on?

You would take avoiding action as you see best.

The alternative is to do nothing, which is silly. It is the "head in the sand" attitude so prevalent in GA - like the map+stopwatch being the "proper way" to navigate.

The inter-communicating TCAS systems used in airliners need to work that way because everybody has the system, and everybody is always (or nearly always) flying under ATC direction, which is assumed to be "right" (provide 100% guaranteed separation) so any traffic proximity is a dire situation where something in the system has already gone badly wrong, and is considered so serious - yet so rare - that a resolution based purely on a level change is considered sufficient.

In the GA OCAS context, excessive traffic proximity can and does occur during routine operations. Even if under a RIS/RAS, ATC will advise of traffic only according to workload. Therefore, traffic awareness increases safety and I cannot see a scenario where it is not worth having because it decreases safety.

One can certainly argue about the value for money. It is pretty poor. With ~ 1 midair per year in the UK, for some 20,000 GA pilots (the total # with valid medicals) that gives us some 400k annual hours flown. Nearly all of the mid-airs occur below 1000ft, so (unless one is into kerb crawling) the time window in which you might have one is exceedingly small.

On TCAS, there seem to be two different points being muddled.

1 - An assertion by some posters that this incident supports a programme to mandate TCAS (as in the certified system in airlines) in all aircraft. - Nigel and Farrell make make important points that TCAS is not a panacea and would have massive issues as it is the whole system/process. It is not just a box of tricks - even though some may use it as such. (besides, mandating #50k and probably 200 lbs of kit and power into most GA aircraft would end the industry)

2 - IO540 (and others) point, is that having GA style traffic information can be a really helpful thing in helping to spot traffic the Mark 1 eyeball didn't. It isn't a system, all it is help in seeing and avoiding - and just like all the other parts of the see and avoid system, it is up to the pilot to work out a resolution and execute it.

There's more than an element of truth in that statement, IMHO.

Getting back to the "Private Flying" related topic (rather than a debate on the finer points of complex collision avoidance systems fitted to the big stuff), how do we address the broadening spectrum of GA?

There is no "one size fits all" any more, the majority of UK GA aircraft are paragliders, paramotors, hang gliders, powered hang gliders, microlights, gliders etc, yet we continue to think in terms of what might be best applicable to conventional light aircraft.

Like the road system, we have to get used to the fact that our airspace has to accommodate an extremely broad range of aircraft types. It seems we are struggling to determine how best to do that in Class G.

Some of the debate here has highlighted that we have a similar problem in this sort of airspace to we have on some rural A roads. We have heavy transport stuff vying with the equivalent of bicycles for use of the same bit of space. Some are, unfortunately, behaving a little like Mr Toad, assuming that they have a right to inconvenience or endanger others because they have a bigger/faster/heavier/more expensive machine. Both have widely varying views as to "rights" yet both are legally equals. No one would suggest making all rural A roads motorways, just to keep bicycles and horses off them, so we shouldn't try to do the same with Class G.

Until we accept that Class G is to be shared equably, without imposing burdens on one or more category of user that are unreasonable, then we will continue to have endless arguments and continue (regrettably) to fly into each other on (thankfully) rare occasions.

VP

The arguments will carry on, VP959, this is pprune after all :)

What will never happen is

a) mandatory transponders for powered VFR traffic in all Class G

and

b) a large % of GA owners fitting the GA TCAS systems (£10-20k and 10-20kg).

So, nothing is actually ever going to change.

Personally, I would like to see mandatory Mode C/S for all powered planes in all airspace. Then I could make the decision on whether the cost is worthwhile. but, as I say, this will never happen.

De facto, much powered traffic already carries a transponder. But many won't switch it on, on "civil liberties" grounds. They moan about the £2500 cost of replacing the ancient Mode A with a new Mode S, while spending £7000 on their Annual...

I worked with both Sophie and Jim only this last fortnight. Both excellent pilots and really nice individuals. This is too sad for words.

Thoughts go to the friends family and colleagues of all five involved in this accident.

Praise and respect to the Air Ambulance crew who first arrived at the scene. I know the media has been slated for showing footage of this but when I watched it I found it very reassuring to see the team was quickly on site trying to help my colleagues.