VFE

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.

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S-Works

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

gasax

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.

PPRuNe Radar

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.

VFE

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.

windriver

That's a worrying statement?

VP959

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

Farrell

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.

Vino Collapso

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.

DX Wombat

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.

NigelOnDraft

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

flybymike

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....

IO540

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.

Farrell

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?

IO540

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.

mm_flynn

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.

VP959

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

IO540

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...

TamedBill

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.

PPRuNe Radar

IO540

You prove my point for me that some people are operating under a misconception. There are people out there who will use their ACAS system (which includes TCAS and everything else in the market) in the horizontal plane. The system is not designed for that and is not accurate enough in providing bearings. They could be up to 30 degrees out.

Turning to the right simply because your display says the traffic is head on could actually be turning you right in to the guy you are 'blindly' trying to avoid. ACAS is only accurate for vertical avoidance manouevres, that is how it is designed.

It is not an airborne radar or an accurate horizontal situation display. It can give you a clue as to where to look and you might sight the traffic involved (or you might not). You can then take appropriate horizontal avoiding action. If you don't sight the traffic and manouevre horizontally based on the picture being given to you by your kit, don't be too surprised if you get a nasty surprise on occasion.