TCAS question

[Crash one]

I know absolutely diddelly squat about TCAS exept that it is designed to help avoid collisions.
Could someone please enlighten an iggerant early stude like me?
Do these devices only interrogate transponder equipped ac thereby making them "blind" to a gaggle of un-equipped gliders or what?
I do not recall reading that Herr Goering's outfit were so equipped Is there anything fitted to light GA that can detect just a lump of aluminium & inform the pilot?
Sorry if this is a stupid question & I will learn to know better in a week or two.

Trevor

[drambuster]

You probably want to get someone like IO540 to answer this ... but in the meantime take a look at:
http://en.wikipedia.org/wiki/Traffic_Collision_Avoidance_System
Yes, participating aircraft need transponders.
I did try one of the portable units available from Transair (and others) but found that they don't give 'bearing' on the cheaper models ... so you have no idea where to look ! Quite distracting (the LEDs were flashing non-stop around the London TMA) so I returned it ASAP. There is another portable model which does give bearing for £1,000 but my experience lead me to believe that it is only worth having if you get a more expensive installation that calls out bearing, range ect over your intercom as that way you're not heads down inside the cockpit studying threats when you're better off just scanning with yours eyes in the normal way.
Panel mounted units such as the Avidyne TAS600 (formerly Ryan) can be installed for around £10K (try Lees Avionics at Booker).
Please bear in mind that on a sunny weekend below 2,400' around the London area then you will find there are dozens of threats from all directions ... and that doesn't include the non-transponder traffic. I believe it is a valuable system in many circumstances but it is not the total answer to weekend GA in high congested areas ! - IMHO

[Crash one]

Thanks for that, which confirms what I thought, they are really expensive bits of kit fitted to expensive aircraft that can only talk to each other.
Therefore their actual effectiveness is limited. In this day & age of high tec things in general it's a bit dissapointing that the mark one eyeball is still king of the hill. Is there any organisation looking at anything better?
What are the chances of a poor mans version of the millitary stuff.
It just seems to me that CAA etc put such a lot of "faith" in these things with talk of Mode C, Mode S & such, that if mandatory would put large numbers of small ac out of the game.
I am no expert on electronics, I'm an engineer / toolmaker but I can't see why a cheap simple even short range on board radar system can't be developed. It seems so obvious that I know I must be missing something pretty simple.
Are there any experts in the subject that can explain in simple terms why not?

Trevor

[IO540]

These TCAS debates run for ever but I think a fair summary is that the driving force behind it is to get something that will trigger the existing TCAS systems on commercial jets.

That narrows the technical options to current Mode C or current Mode S. The CAA appears to think that Mode S is necessary because Mode C would generate too many returns and swamp the radars (that's my understanding).

There are other ways to get traffic warnings but they don't meet the above requirement so they are a bit academic.

Also nobody in authority cares about GA-GA conflicts and I think that's probably reasonable. They are extremely rare and technical solutions based on existing transponder technology are expensive, £10k as mentioned above. They also don't do much because so many planes are not transponding.

It's possible that if/when Mode S is made mandatory for VFR, other solutions will emerge on the back of that (Mode S provides a means of unsolicited broadcasting of the aircraft position) but I don't hold out much hope for a universal adoption because most of the GA scene, UK and elsewhere, won't spend any money they can avoid spending.

[steve130553]

If, and I think that you are correct, that the driving force behind mode S is the commercial traffic being able to "see" the other traffic, and that there is really no benefit for GA to GA use; then surely it should be the commercial operators who fund the GA fitting of the Mode S trandsponders?;)

[IO540]

surely it should be the commercial operators who fund the GA fitting of the Mode S trandsponders

Yes but that's not the way the world works :)

The entire aviation regulatory / administration apparatus around the world is geared for just one thing: commercial air traffic.

GA exists in the nooks and crannies, cracks and crevices that are left, which are for the most part safeguarded by ICAO. They are most definitely not safeguarded by national politicians.

In the few countries that have a significant amount of GA activity (the USA is big of course, and in Europe you have the UK, Germany, France) there is also support for GA through influential people doing private flying.

But that's about it. European GA could be abolished tomorrow and the Big Brother watching intellectual elite would never notice. Sad, isn't it?

Curiously, mandatory transponders have been an ICAO requirement for years. The UK CAA, despite being largely "owned" by the airlines, has protected GA from this by filing an exception and so have most other CAAs. For some reason, probably airline pressure, this is ending.

[BEagle]

If you get the chance, read the PFA's paper rebutting the ludicrous CAA 'partial regulatory impact assessment' concerning Mode S. It destroys the CAA's arguments in every area.

Personally I feel that the main CAA enthusiasm lies in the potential ability to know, with Mode S, who is doing what and where. They are seemingly more keen on increased surveillance than increased safety...

The L-band congestion argument is utter tosh. If that was the case, why is it not a problem in the US with its much larger GA population and activity in the vicinity of large aerodromes?

These are my alternative proposals:

http://i14.photobucket.com/albums/a341/nw969/xpdr3.jpg

I also consider that no new non-Mode S installations should be permitted after 31 Mar 2010.

[bookworm]

Therefore their actual effectiveness is limited. In this day & age of high tec things in general it's a bit dissapointing that the mark one eyeball is still king of the hill. Is there any organisation looking at anything better?

If you want technological assistance in detecting other aircraft, you can do so with or without the cooperation of the other aircraft. Without it, you need a primary radar system, which is hopelessly expensive, heavy and power consuming.

So detection relies on cooperative systems, which means that everything to be detected must be equipped with the same sort of technology -- it's pointless for 50% of aircraft to be equipped with one system and 50% with the other.

Within the class of cooperative systems, there are again two possibilities. Either the detected aircraft needs to respond to interrogations from the detector -- which is how TCAS works in detecting transponder-equipped aircraft, or it needs to broadcast its presence (including its position) on a regular basis -- something called ADS-B.

A number of different technologies have been proposed and evaluated for the communications part (datalink) of ADS-B. While there are minor differences between them, it essentially comes down to picking a frequency and choosing a power budget. None of the technologies is fundamentally cheaper or less power hungry than another. The bulk of the purchase cost, as always in avionics, comes from development and certification costs. Thus whatever is chosen, if you turn it into an international standard, it's probably going to cost a 4-figure sum.

One of the datalinks, which will almost certainly be chosen as the standard for ADS-B in Australia, Europe and for larger aircraft in the USA, is called 1090ES. That is the datalink over which the Mode S transponder works, and virtually every recent Mode S transponder is capable of doing ADS-B if you plug an appropriate GPS into it.

Thus as well as responding to TCAS and aiding detection by ground radar systems, the Mode S transponder will permit you, in years to come, to participate in ADS-B. There are already desktop ADS-B detectors out there (e.g. Kinetic's SBS-1), and it's only a matter of time before they become available for cockpit use.

The bottom line is that if you want help from technology in detecting other aircraft, you need to get behind the move towards universal equipage with Mode S, even if you don't like the way that the CAA is approaching the issue.

[bookworm]

These are my alternative proposals:

The fundamental problem with these proposals (which are extraordinarily complex, are you by any chance a civil servant BEagle? ;)) is that for the most part they require transponder carriage in known traffic environments (A-D) and don't in E-G. That's pointless -- transponders are required as an alternative to having to get permission to be there from an ATS unit. It's the airspace in which traffic currently operates without coordination with other traffic where transponders are most needed.

[BEagle]

Hardly 'extraordinarily complex', bookworm - just enter the chart with your a/c category and check whether you will need any transponder in the classes of airspace in which you wish to operate.

E.g. Piper Cub which never intends to operate under IFR or in Class D - no transponder needed. PA28 which operates in and out of Class D airspace and is used for IMC training - Mode C transponder required.

TCAS protection against GA aircraft operating under IFR in the open FIR is one thing, mandating that all GA aircraft should carry Mode S just to 'improve coordination' in the open FIR for the principal benefit of protecting LoCo airliners wanting to operate outside Class A-D airspace is quite another.

And no, I am not a civil serpent. Neither am I an air-trafficker or member of any other flying prevention organisation...

Mandatory transponder equipage should be reasonable, affordable and proportionate. The CAA's proposals are none of these.

[robin]

But the issue there is that we have Piper Cubs and PFA types operating safely from strips within Class D now with the agreement of the local ATC. Usually they have specific arrival and departure routes so that they can continue to operate.

Does your proposal mean that these agreements will cease? If so, I suggest that such situations need to be included in the exceptions

[Funkie]

There appears to be two different discussions happening here! TCAS and Mode S, which are very different beasts…

Crash One

TCAS or ACAS, generally speaking, is a system used by commercial operators and I believe it’s fitted to a number of non-civilian types. It works on the principle on the SSR, where a signal is sent by one a/c, searching for responses from transponders within a selected range, in both the vertical and horizontal. Where found, the system will calculate if a conflict occurs and give either a TA (traffic advisory) where no conflict occurs at that point in time, or RA (resolution advisory) when you are given guidance on how to manoeuvre you’re a/c to avoid collision.

If you are operating in the light a/c GA world, this system is financially prohibitive. Having a quick look at the Honeywell site gives a shock to the system – I didn’t realise they were that expensive!! There are cheap systems on the market, but is your life really worth so little!! See and avoid……

Assuming you operate in this environment and as your profile suggests, Scotland where we have a huge chunk of Class G, having a Mode C transponder installed at say £1500 - £2k is almost a no brainer. It will assist flight safety to a great deal and also assist ATC in accurately identifying your position – no bad thing if you ask me.

Mode S, in my opinion is a very different matter…
As I understand, the main push behind this system is for accountability and financial reasons from the Campaign Against Aviation, where your flight details are recorded and bills issued for use of the airspace. I can’t see how it provides any further help in flight safety over the current Mode C equipment.

The table posted by Beagle seems to be a very simple and sensible proposal, but then that’s not going to make very much money for those in the big grey building. I agree that mandatory usage is not unreasonable, but it must not be a sweeping all must carry Mode S statement.

Robin – I can’t see why such agreements would stop. Your types under from the table above would require no more than a simple Mode C unit. To be honest, you may even be asked not to use it within certain parts of Class D to minimise RA’s and the resulting MOR’s.

[BEagle]

Robin, yes, my proposal is regrettably based on a 'give a little - or lose the lot' compromise principle.

But surely it would be possible to reclassify the entry and exit corridors which you describe as Class E routes? VFR only and no transponder required in such corridors?

[IO540]

As I understand, the main push behind this system is for accountability and financial reasons from the Campaign Against Aviation, where your flight details are recorded and bills issued for use of the airspace

Not sure why this one keeps coming up, since there is by far insufficient radar coverage to do the monitoring.

[bookworm]

Assuming you operate in this environment and as your profile suggests, Scotland where we have a huge chunk of Class G, having a Mode C transponder installed at say £1500 - £2k is almost a no brainer. It will assist flight safety to a great deal and also assist ATC in accurately identifying your position – no bad thing if you ask me.

Mode S, in my opinion is a very different matter…
... conspiracy theory snipped ;) ...
I can’t see how it provides any further help in flight safety over the current Mode C equipment.

Two points.

I would strongly support the idea that aircraft currently equipped with Mode A/C SSR should not have to re-equip until the Mode A/C unit breaks (or ADS-B over 1090ES is adopted). For now, Mode A/C is fine in the numbers that it's currently used. But there are spectrum congestion issues that would make it difficult to move to the sorts of levels of equipage that would be desirable.

I don't believe that there's a technical reason why Mode S equipment needs to be more expensive than Mode C. At the moment the volumes of Mode S are small enough that it commands a premium. Mode C is discounted because of the introduction of Mode S. But in the long run, they're just radios with some logic attached.

[BEagle]

".....there is by far insufficient radar coverage to do the monitoring."

At present that may well be the case in many areas.

But were Mode S to become mandatory, particularly when linked to GPS and downlinking via ADS-B, it wouldn't take rocket science to come up with remote ADS-B reading heads to track and charge you.....:mad:

The FRUIT and garble which the CAA claim would cause RF congestion is NOT a significant problem at lower levels - particularly at 2-3000 ft in the open FIRs.

[shortstripper]

For TCAS to be effective ALL aircraft would have to be equipped with transponders. Many (like mine), either, literally could not be so equipped, or financially would be deemed not worth the expense and scrapped (or exported/stored/displayed). There isn't a portable unit available that is small enough or safe enough for use in ALL aircraft, and I can't see that there ever will be. The CAA are happy to go along pretending that the market will make one available for a few hundred quid because it suits their argument. They couldn't give a fig if there's any truth in what they're saying, so long as they get their way and get to suck up close to the airlines maybe?.

So, for TCAS to be of any real use, we will have to not grant exemptions and accept that many of our lovely older and more interesting types will never again grace our skies, and that the gliding and microlighting fraternity will be greatly reduced (and may even be forced to pack up due to fewer members).

I doubt this will happen, and I doubt the CAA really think it will either. They are bound to have to grant exemptions, so the question then is ... why make mode S compulsory for the rest? If not all aircraft are equipped, there is no safety benefit for us as TCAS is useless. Also, airlines would be on very dodgy ground operating outside of controlled airspace with passegers, as safety would be much reduced. So, are they offering to allow transponder equipped aircraft into previously forbidden airspace? ... Nope! So I see no benefits to us at all, and dubious benefits to the airlines ... unless?

There's either a future plan to increase the areas of controlled airspace and squeeze non transponder equipped aircraft into smaller and smaller areas (advantage to airlines), or, plans are afoot to maybe introduce airspace usage charges for GA ... or at least, introduce the framework to make this possible at some point (advantage to the CAA as it will be able to justify its otherwise dwindleing existance to goverment and protect its future).

Who knows? :sad:

SS

[robin]

Robin, yes, my proposal is regrettably based on a 'give a little - or lose the lot' compromise principle.
But surely it would be possible to reclassify the entry and exit corridors which you describe as Class E routes? VFR only and no transponder required in such corridors?

I think it would be quite easy to reclassify the corridors. All it would take is for the relevant authorities to agree to giving up some of their airspace. Dead easy......

[Fuji Abound]

Let me declare at the outset that I was not in favour of the mandatory introduction of mode S.

However, whilst I am “happy” to rely on existing services and my own eyes to hopefully spot traffic in VMC outside of CAS I am conscious that with new and more capable aircraft becoming available it is possible there will be more pilots operating in IMC outside of CAS. It is in this respect I have a problem.

Aircraft operating in IMC are required to be equipped with at least mode C and presumably the majority will convert to mode S. However it has become increasingly apparent to me that there are a good many pilots who are prepared to operate in conditions that are either IMC or very close to, who are either not instrument rated or are not operating suitably equipped aircraft or both. This will include those who decide to nip through a gap in the clouds to get on top, but find themselves in IMC for short periods, those that fly very close beneath or above a cloud layer and those that fly when conditions whilst not IMC are as near as you can get. The fact that these pilots are not instrument rated, not flying in suitable equipped aircraft and breaking the law is all irrelevant for those that are on an IFR flight and come into conflict with them.

I suppose in the same way that many certified aircraft are fitted with far better avionics it is also the case that so are many home builts, and non certified or non IFR compliant aircraft. Of course this in turn gives the “operators” the confidence to fly in more marginal conditions.

[mm_flynn]

I would strongly support the idea that aircraft currently equipped with Mode A/C SSR should not have to re-equip until the Mode A/C unit breaks (or ADS-B over 1090ES is adopted). For now, Mode A/C is fine in the numbers that it's currently used.

I agree whole heartedly and think the CAA has wound up taking a good idea and generating a great deal of negative momentum. Given the relatively slow proposed rollout of Mode S ground stations, the head long rush to drive more expense into GA seems unreasonable. Something more along the lines of:

1 - Encourage all airspace users who can (i.e. have generators) to install or upgrade to at least Mode C (because it makes everyone's life easier and this is probably the majority of the aircraft flying on any given day)

2 - Regulate to require any replacement transponder to be Mode S (as Bookworm said the cost difference between a new Mode C and new Mode S isn't worth getting worked up about. (possibly allow the installation of used Mode C units as replacements or new fit in currently un-equipped aircraft)

3 - Acknowledge that there is currently no practical option for aircraft without generators and stop trying to legislate a product development into existence!

4 - Most important - given all of the value that ATC, CAT, the military, the government (UAVs for the police etc) and the Treasury (through auctioning off the released spectrum from less primary radar to the mobile phone operators) will get from Mode S - give something back to GA for spending their money - like traffic data. In the US they got half the fleet over to Mode S with just the offer of traffic data!

[Funkie]

IO540 – I wouldn’t have said that radar coverage is that spartan! Perhaps in the Highlands, North West of Scotland and parts of Wales, then yes. However, this is not where the majority of the traffic we are discussing, with regard to Mode S, operates.

Shortstipper - I’m not too sure there are that many types, even PFA or on Permits, that would be that financially hit to the extent that a basic Garmin GTX320A would render them grounded!! It’s all in context. Do you fly in controlled airspace frequently, mixing with the big boys, or in the open FIR at higher altitudes? If not, then why bother with such equipment?

Airliners are on very shaky ground when operating in the open FIR on a RIS, which is a very good reason to have a transponder. Recall incident with Flybe Dash 8 and a couple of Fast Blacks over the Irish sea?? I wonder how many times you have flown fairly close to the base of overcast cloud and never thought that something may be descending through it?? A transponder in this case would make you more visible to ATC (if within radar range which is very likely) and the a/c if TCAS was installed. In fact, it could save your bacon!!

Robin – You seem against the idea of having such equipment fitted to you’re a/c. Can I ask why?



The way that I look at transponders is in the realm of flight safety. It’s a relatively inexpensive bit of electronic magic, that when the proverbial hit’s the fan and you are getting even a FIS from a chap/chapess with radar, SAR will have an infinitely better chance of getting to you. Of that there is no doubt.

[robin]

IO540Robin – You seem against the idea of having such equipment fitted to you’re a/c. Can I ask why?
The way that I look at transponders is in the realm of flight safety. It’s a relatively inexpensive bit of electronic magic, that when the proverbial hit’s the fan and you are getting even a FIS from a chap/chapess with radar, SAR will have an infinitely better chance of getting to you. Of that there is no doubt.

It actually depends on what a/c I am flying. When flying an aircraft with no power supply - just a battery then I will chose the most appropriate use of the limited life of the battery. I would prefer to power my radio and my GPS.

If I am told I have to power a transponder as well, then I have a decision to make as to which one(s) I don't use

As I fly almost exclusively in areas of poor radar service for GA (they tell me to standby a lot) I get little back for any potential spend.

You might say that by transponding I am helping flight safety by letting guys with deeper pockets than me see me on their TCAS. I don't have that luxury myself, although I have been nearly run down a few times by pilots flying straight and level and acting in what I can only describe as a bovine manner, ignoring the rules of the air.

I am still alive, as I don't trust anyone to take care of my life for me when in the air.

You have to remember that most of the policies emenating from the CAA are designed to help well-equipped aircraft. Very little is designed in for PFA-types or show any understanding of issues, such as power requirements, radiation issues or w/b when an aircraft, flown single-seat is already at MAUW

What may be being suggested is that the lightest and cheapest aircraft are to be not only equipped with a transponder but also a TCAS. 2 pieces of expensive kit, costing more than the purchase value of, say, an Evans VP, but adding nothing to the owner/operator, who has been flying safely for many years without them.

Yes, in certainly areas in the SE or around the tight spots we need to be sure we are flying safely - that might involve simply weaving to show a bigger profile. But in some areas in the south and west the need has not been demonstrated

[Fuji Abound]

"Yes, in certainly areas in the SE or around the tight spots we need to be sure we are flying safely - that might involve simply weaving to show a bigger profile. But in some areas in the south and west the need has not been demonstrated"

Yes my point exactly as set out in my earlier post.

Is it your and everyone elses view that the issues I raised earlier are / are not of concern?

[rustle]

Aircraft operating in IMC are required to be equipped with at least mode C and presumably the majority will convert to mode S.

Do you have a reference for either the statement or the assumption above?

[Fuji Abound]

Sorry - I should have made it clear that this was a reference to BEagle's recommendations in so far as proposed changes are concerned.

My other comment was made on the basis that if you use your aircraft to operate in IMC, there is a good chance operations will at least include class D and maybe class A and given the cost of already keeping the aircraft legal to do so it would seem likely to fit mode S.

[shortstripper]

I’m not too sure there are that many types, even PFA or on Permits, that would be that financially hit to the extent that a basic Garmin GTX320A would render them grounded!! It’s all in context. Do you fly in controlled airspace frequently, mixing with the big boys, or in the open FIR at higher altitudes? If not, then why bother with such equipment?

Airliners are on very shaky ground when operating in the open FIR on a RIS, which is a very good reason to have a transponder. Recall incident with Flybe Dash 8 and a couple of Fast Blacks over the Irish sea?? I wonder how many times you have flown fairly close to the base of overcast cloud and never thought that something may be descending through it?? A transponder in this case would make you more visible to ATC (if within radar range which is very likely) and the a/c if TCAS was installed. In fact, it could save your bacon!!


Funkie ...

Robin has pretty much addressed what you have said, but just to re-iterate.

I would be financially hit! and so would others like me. My T31m has cost me around £2500 to buy as a glider and convert. I'm a farm manager on a pretty low wage and have 5 kids. Operating a small single seater from a home strip is about the only way I can afford to fly. Quite apart from the fact that there is physically no room, enough power or payload to carry a transponder ... it would also cost more than the flippin aeroplane!

You say "Do you fly in controlled airspace frequently, mixing with the big boys, or in the open FIR at higher altitudes? If not, then why bother with such equipment?" ... No I don't, and I wouldn't bother, it's the fact that it may be made compulsory that gets me bothered! :mad:

The point I was making is that TCAS is bl@@dy useless as an aid to cover your arse if not everybody carries one. If the likes of me are allowed to continue to operate non transponder equipped (which I sincerely hope is the case) then TCAS in non controlled airspace is not going to help much is it?

SS

[BEagle]

And long may folk such as Shortstripper continue to enjoy basic VFR flight freedom without some suit in the Belgrano requiring them to fit a transponder!

There should reasonably be no difficulty in denoting low level VFR-only Class E routes within Class D CAS to afford access to non-tranponder equipped aircraft of less than 2000kg.

The cost of fitting a transponder to an aircraft which does not have an electrical system or height encoding altimeter is not insignificant. It most certainly would affect a lot of people if this stupid 'Mode S-for-all' idea ever became reality.

[zkdli]

I personally have no issue with carriage of transponders or non carriage :) My problem is that at the moment if you don't have a transponder there are alot of aircraft out there that have no protection. We can all say that we operate see and be seen. And we can also all say that we have almost been hit by some numpty that either didn't give way when he should have or he just didn't see us.
What you have to convince their majesties in the ivory towers is that if you don't have transponders, be they mode "C" or Mode "S", you won't get in to CAS when you are not supposed to be there:)
if you can do that, then you wont need a transponder.
BUT I don't think the EASYJET or RYANAIR pilots will accept that you dont need a transponder when a microlight goes in to CAS with no transponder and gets very close to them.

[robin]

No - the problem we will be facing is that Sleazyjet and Chavair will be routing through Class G to save fuel and time and expecting the microlights/gliders and VP1s to squawk so that they can use their TCAS for separation

Worse, they will use the fact that they are able to choose their own routings as a way of depriving GA access to Class G around regional airfields using safety as an excuse

Given the savings they expect to make (ie extra profit) they could pay for the fitting of transponders for everyone.

Unfortunately they fail to understand that we can't all fit transponders to all our aircraft.

Even the military won't all be fitted with transponders, so you will all be at risk of being wiped out by a Tornado, even if you are TCAS equipped.

[englishal]

The way I see it is that the introduction of Mode S is designed to "protect" CAT from GA aircraft while they are in the Class G (the airliners that is)......Nothing wrong with that, collisions do happen as we have seen recently with the Glider and the Hawker in the USA.

There are several ways it appears this can be done:

a) Either madate that all aircraft are transponder equipped, so CAT can see them on their TCAS and be responsible for their own safety
b) Increase the size of CAS so that the CAT aircraft have climbed to a safe level before leaving CAS or entering enroute CAS

A far simpler and cheaper option IMO, which would not force transponders on aircraft that can't have them would be to introduce Mode C vales, like the US has. So if you want to operate within 30nm (or whatever) of an airport while remaining outside their CAS you must have mode C fitted and be transponding. If you want to enter their CAS, you will require Mode C and an ATC clearance, and to enter airways Mode S.

This way VFR bimblers in simple machines can remain outside of these areas, and go about their business not transponding or communicating. Training aircraft and people who enjoy the freedom of flying on long cross countries would require Mode C as a minimum, as many already have. Funkier machines or people who use their aircraft as a form of transport under VFR and IFR in the airways would realistically require Mode S.

I will always fly with a transponder, it is a personal choice, though do object to being forced to spend 000's of pounds on a piece of kit to replace my perfectly serviceable mode C transponder.

[zkdli]

Robin,
Just which airfields that don't already have commercial operations at the moment are you thinking of? If you think that they will be operating below FL100 for all of their time in Class "G", I just don't know what route you are thinking of. Also I don't know of any airline that will willingly operate in Class "G" without a radar service of some kind.:hmm:

[IO540]

I don't get this "airliners in Class G" business either.

Operations from Class G airports usually involve rapid climbs/descents into Class A. The exposure of the airliner is very short and it would be under a radar service from somebody.

I reckon Mode S is coming because of all the CAS busts by GA.

The CAA would do themselves a big favour by doing something on the PPL training side of things.

[rustle]

A far simpler and cheaper option IMO, which would not force transponders on aircraft that can't have them would be to introduce Mode C vales, like the US has. So if you want to operate within 30nm (or whatever) of an airport while remaining outside their CAS you must have mode C fitted and be transponding. If you want to enter their CAS, you will require Mode C and an ATC clearance, and to enter airways Mode S.

This way VFR bimblers in simple machines can remain outside of these areas, and go about their business not transponding or communicating. Training aircraft and people who enjoy the freedom of flying on long cross countries would require Mode C as a minimum, as many already have. Funkier machines or people who use their aircraft as a form of transport under VFR and IFR in the airways would realistically require Mode S.
How does that work in:
The area between Heathrow and Gatwick
The area between Luton and Stansted
The LLR near Manchester

Do those areas become "exceptions", do we just accept that non-transponder aircraft can't use them, or have I missed something? ;)

Infact, having just looked at a chart, by the time you've put veils that size (or similar) around a couple of the busiest airports in the south-east, you've decimated gliding at Lasham and Dunstable (and others, but you get the idea) made places like Southend/Blackbushe/NorthWeald! (and others, but you get the idea) all transponder-required airports.

May as well just make it a mode C veil from Coventry south ;)

[BEagle]

"The CAA would do themselves a big favour by doing something on the PPL training side of things"

Oh, yadda, yadda, yadda. Here we go again. More "Praise de Lord for GPS" coming up soon from IO540....

It's not the recent PPL pilots who bust CAS - it's the lazy so-and-sos who cannot be bothered to navigate properly irrespective of whatever system they use.

The Mode S debate must allow for everyone who flies GA. Whether VFR PFA types pottering about in wooden permit aeroplanes or silicon chip enthusiasts who fly in CAS regularly in tin Spamcans.

[IO540]

You should assume less, Beagle, and wonder instead what is driving this whole thing.

Do you have data on airspace busts versus pilot age, currency, # of years PPL held, etc? The ontrack survey seems to have missed that, IIRC.

[rustle]

Do you have data on airspace busts versus pilot age, currency, # of years PPL held, etc? The ontrack survey seems to have missed that, IIRC.

For your assertion that the majority of airspace busts are by "new PPLs" to sit comfortably with your assertion that "> 90% of PPLs drop out after year one" requires that nearly all new pilots still flying are busting airspace regularly. (Otherwise the numbers don't add up)

Do you have a reference for that phenomenon?

[Fuji Abound]

I am still interested how pilots operating IFR / IMC in open FIR without a RIS view this.

I happen to live very near a VOR that is used a lot for training, is on a major airway and used by pilots operating both VFR and IFR. I find it interesting how often I see aircraft flying just below the base in and out of IMC. I know some of the aircraft are not IFR certified.

Do you just rely on the big sky theory to maintain seperation?

Do you wish in these circumstances every aircraft had a transponder?

Do you wish every pilot obeyed the rules and you could safely assume they would not be in front of you as you broke IMC?

How many of us have actually used TCAS in a light aircraft?

[IO540]

For your assertion that the majority of airspace busts are by "new PPLs"

Where?

[Crash one]

Well, well, my question certainly seems to have opened a can of worms here.
Shortstripper has hit the nail on the head regarding the type of flying I plan to do.
All this TCAS & Mode c/s/what ever is just a total & utter waste of time to even contemplate from a cost & weight/power consumption point of view.
I do not intend to go near class A,B,C & probably D airspace, so I do not envisage ever needing to know where the "big stuff" is.
A simple five bob GPS will tell you where you are. All I want to see is perhaps a ten bob GPS compulsorily fitted to or carried by everything that flies that will comunicate with every other ten bob GPS in a radius of 20nm. & display said information on a screen, proximity warning also should not be beyond the bounds of possibility. Ten bob is not meant to be literal by the way!!
This departs completely from "normal" aviation thinking which is usually the current buzz word carried down the mountain on tablets of stone by "them".
It requires some sort of radical out of the box design work by some forward thinking electronics whizkid.
We have mobile phone technology going through the roof for the cost of a fish supper, we have GPSystems becoming ever more accurate, we have calculators running off solar power.
I am probably being ridiculously simplistic here, how difficult is it??
If such a device were to be produced at a cost of a few £hundreds, I would guess that the manufacturer would make a fortune from GA, Microlighters Gyros Hillwalkers & anyone who wants to know where help or danger is, depending on how you use it.
I apologise for screwing up a perfectly logical thread based as it is on current thinking. But I am hoping to generate "out of the box" ideas.

Trevor. NPPL student with a yen for a Kitfox.

[BEagle]

For any GPS to 'communicate' with another GPS would require:

Your position ro become a floating waypoint.
This information is somehow uplinked. How do you propose to do that?
The information is downlinked. How do you propose to receive it?
The information is displayed. For it to be of any use, it would require a rapid refresh rate.
Now think about the bandwidth needed for several 'GPS' transponders to do this.

Or just LOOK OUT OF THE WINDOW!

[Crash one]

For any GPS to 'communicate' with another GPS would require:

Your position ro become a floating waypoint.
This information is somehow uplinked. How do you propose to do that?
The information is downlinked. How do you propose to receive it?
The information is displayed. For it to be of any use, it would require a rapid refresh rate.
Now think about the bandwidth needed for several 'GPS' transponders to do this.

Or just LOOK OUT OF THE WINDOW!
I originally started this thread to see what people thought about the idea of a piece of cheap equipment that would not require any communication FROM other traffic for an a/c to know of that traffic's existence.
I would aggree that the GPS is not the answer, I think I got a bit off my original track by suggesting something to be carried by all.
What I think is needed is some form of onboard primary radar like the military "target aquisition" stuff but at an acceptable price. Something simple that will detect a chunk of aluminium heading your way, with no input from the "target". Of course this will never happen as if it were possible "someone would have done it by now". Where have I heard that before?
However as for "looking out the window", I presume you believe that I need to be advised to do this?
Perhaps I should point out that, contrary to popular belief, not all student pilots are as thick as two short planks. Whenever I fly from my local flying school I do try to get a window seat, so far I have always been successful & always in the front.
I spend the entire flight looking at the view apart from the occasional glance at those clock things.
These last remarks are not directed at you or anyone personally, but I have read "look out the window" so many times that I feel I must answer I DO!!! But I can't see through the roof or the floor. Please don't tell me what the yoke or stick is for.
Now, why don't airline pilots do that & make the whole thing a lot easier, put CAA, NATS etc out of business?? Or is it just the poor light GA non commercial VFR pilot who has to do it, while the big boys sit doing the crossword or playing chess?

[BEagle]

"What I think is needed is some form of onboard primary radar like the military "target aquisition" stuff but at an acceptable price."

That is naiive in the extreme. Do you have any idea what 'military target acquisition radar' actually is? The acquisition cost, installation cost, power requirements and siting difficulties of even a simple cloud and collision warning radar in a SEP spamcan would be enormous. Let alone the CAA mod fees.... Let's just say tens of thousands of pounds.

You have to realise that all the silicone chips in the world won't be enough to protect you from other aircraft under VFR.

Remember, Visual Flight Rules mean just that!

[Crash one]

I am not quite that naive.
I am well aware of what military "target aquisition radar" is. I was not proposing canibalising a Tornado. Lets forget the military stuff & try from another direction.
Some altimeters are expensive & are hooked up to expensive transponders, other altimeters are cheap & can be strapped to ones wrist so one can leap from an a/c & know roughly when to pull the string.
Both read altitude.
Now, current primary radar systems are expensive, complex, heavy, big etc. So I don't propose ransacking West Drayton.
However, intruder alarm systems have a very short range, could that be improved? infrared cameras have a slightly longer range, could that be improved? Some expensive cars I believe are fitted with proximity detection systems to prevent rear ending the guy in front, how much £ & how far in front?
I'm sorry I am merely a thinking person, I am a retired toolmaker / machine designer, I am not an electronics man at all. but I can think "what if, based on current technology?"
OK it may not be possible, certainly if CAA certification has to be considered, price wise. So much for progress. But a few years ago TCAS wasn't possible.
I suppose we just have to wait, grin & bear it, pay up, shut up & generally cowtow to them what know better.
Would Mr Trevor Bayliss please stand up!!:ugh: :{

[IO540]

One example of what you may be thinking of is a radar altimeter. These send a beam, fairly wide, downwards and measure the time delay.

A KRA10 is about £6,000 installed. Still too expensive for most spamcans. OK, the manufacturing cost is about £300 (same as a Garmin 530 for that matter) but that's the way things go...

Detecting a target without a reasonable idea of azimuth is not much use. Which is why the cheap £500 traffic warning boxes are useless, IMHO.

[BEagle]

Even the latest TCAS technology cannot provide azimuth conflict resolution....

A 'radalt' actually uses radio, not radar. The emitted signal is frequency modulated and the difference between the frequency of the reflected signal and the main signal sent at the time provides an indication of height.

We had a radar altimter in the Vulcan, as well as the radio altimeter. Used for accurate high level height measurement, it was a huge and very expensive device!

[soay]

For any GPS to 'communicate' with another GPS would require:
Your position to become a floating waypoint.
This information is somehow uplinked. How do you propose to do that?
The information is downlinked. How do you propose to receive it?
The information is displayed. For it to be of any use, it would require a rapid refresh rate.
Now think about the bandwidth needed for several 'GPS' transponders to do this.
Or just LOOK OUT OF THE WINDOW!
There must be something better than the mark one eyeball! You're thinking about it in the context of current GPS receivers, but why would you want to start from there, when it has all the problems you listed?

The kind of device that's required would simply have to broadcast its GPS position, using the same technology as wireless broadband. The amount of data involved (ID +coordinates) is tiny, and by transmitting at low power, so that only nearby aircraft could pick it up, the bandwidth should not get saturated and the current consumption should be low. The back end processing would involve keeping a list of the most recent positions and using that to calculate the track of each aircraft, so that conflicts could be identified. Such a device should be able to operate on rechargeable lithium cells, so there would be no excuse for even gliders not to install it.

Hopefully, by publishing the idea here first, nobody should be able to patent it, so competition should keep the price low. :)

[IO540]

It does in fact have to carry a few miles. The closing speed of a 150kt spamcan plus a 737 can be quite high. A few miles' range needs more RF power than one is going to get with small lithium cells.

Anyway, as has been written here already, 1090ES is the way to do this. It's established and internationally accepted.

The reason prices are not as low as they could be is that certified avionics is an international cartel, allowing stuff to retail at 10x to 20x manufacturing cost. Everybody except the end user loves it; the avionics shops like the reseller margins, the installation charges, the distributors like their margins... and this "find a stream of money and position yourself alongside it" is what keeps the whole world rolling along nicely :)

On Permit planes, one could do a lot.

I am sure products are being developed right now. But nobody, not even a bold new player who has nothing to lose in bombing the market and pi**ing off the distribution networks, is going to announce a product now, before Mode S is mandatory. This is because he will know that Garmin, etc, could push out a sub-£1000 version of a GTX330 within a few months if they wanted to, and why show your hand early?

BTW, a KRA-10 is a radar altimeter

https://www3.bendixking.com/static/catalog/viewproductdetails.jsp?pid=83

[BEagle]

You're right! I guess that's the result of modern radar development.

Similar to the 'parktronic' devices fitted to some cars - although with a bit more wattage!

[englishal]

I don't know why these pieces of kit need to be so expensive. You could knock up a cheap Radalt for a couple of hundred quid these days, if that.

I like the idea of re-radiating ones GPS position. If everyone did it, there would be no need for transponders or even radar. Could even use the Mobile phone cells to collect the data, with no additional infrastructure required. Send it off via Inmarsat and you have glodal coverage.

[robin]

I'm sure NATS and their suppliers would love that!

[bookworm]

I like the idea of re-radiating ones GPS position. If everyone did it, there would be no need for transponders or even radar.

... which is why Air Services Australia, with huge amounts of airspace to cover, are so smitten with the idea that they may well subsidise equipage with ADS-B over 1090ES so they can save $100 million on radar systems.

[Crash one]

Great guys, this is nearer the right direction.
Broadcasting GPS units sounds good, & the technology doesn't sound impossible, I wish I knew more about the electronics stuff, there are other markets for that as well, I'm sure the Mountain rescue services would appreciate a distress call with a pinpoint location included, especially when the poor sod that fell down the mountain doesn't know where he is. So going a step further & add a button that changes the signal to a distress call shouldn't be difficult. I'm sure a lot more people than just the aviation industry would be interested, mass market = cheaper?
The problem of azimuth resolution may not worry many people, just the knowledge that something is on a converging track would do me.
As for upsetting NATS etc, why should that be a problem? If it were self contained ie:- not hard wired to the aircraft, would that make it unregulatable?
As for a radar based device, how much wattage / amps is required to return a signal from say 10 miles? If that requires a battery the size of a porta-cabin then it's no use.

[grob103]

For any GPS to 'communicate' with another GPS would require:
Your position ro become a floating waypoint.
This information is somehow uplinked. How do you propose to do that?
The information is downlinked. How do you propose to receive it?
The information is displayed. For it to be of any use, it would require a rapid refresh rate.
Now think about the bandwidth needed for several 'GPS' transponders to do this.
Or just LOOK OUT OF THE WINDOW!

Flarm (http://www.flarm.com/index_en.html) does this; GPSs that talk to each other within 1-2nm. Developed for glider pilots in the Alps.

Not proposing or advocating anything, just pointing out a nifty bit of kit.

[steve130553]

I am sure that all pilots out there ( whether commercial or GA) would, if presented with a simple to use, low cost (say £250 fitted), low power (ie nicad rechargeable) unit that would be able to be shown,without doubt, to enhance the safety of us all; then we would all purchase and install the same. So then surely, this should be given as a task to the CAA to commission the design and manufacture of such a unit providing a clear case as to how it will enhance the safety of aviation as a whole, on the clear understanding that we would all purchase and install the kit.

If this was so tasked to the CAA then I can safely say that we would hear no more of mode 'S' or any other similar unit until at least 20 years hence ( by which time there probably wont be a CAA anyway)!:8

[robin]

That's what we've been saying all along. In their proposal the CAA claim to have taken a leading role in the development of the low-powered, low-cost transponder.

But when you ask them just what that means, they look all shifty and tell you that it is not for them to mess with the market.

My own view is that they know that sailplanes, microlights and very light aircraft won't go for anything over £1k, and have sort of been saying that Mode S won't be mandated unless there is a cheap one available - at the Safety evening a figure of around £500 was bandied about.

But, the CAA are not doing anything to make this utopian piece of kit happen.

By all acounts, those in the know are finding the CAA very hard to deal with on this matter. They have put in years of work with the aim of having Mode S installed on everything, and they are not going to let a small thing like making 28,000 aircraft owners pay out huge sums of money stop them from going ahead.

My gut feeling is that we will see this go to judicial review.

[BEagle]

And isn't their so-called low-cost, low-power Mode S device to be restricted to VFR only?

Not much use to those who can currently fly in IMC with Mode C quite safely.