Mode S petition at No 10
 

I did a search and got too many hits to decipher, so forgive me if someone has already posted this but,
A petition to Downing street about Mode S can be found here:
http://petitions.pm.gov.uk/transpondermodeS/

It was started by Nick Bloom.

i know all the big brother arguements, but lets face it, every high street is infested with cctv now, isn't mode S, susposed to be a safety device ?
if it saved me getting "involved" with a fast moving military jet, i'd think it money well spent, or am I being misinformed about mode s ?

The concept of Mode S to help air safety is fine, what isn't fine is the fact that there are no cheap, battery operated versions available for non electric aeroplanes - gliders etc.

Also it starts us down the road of airspace charges for every single flight, VFR or IFR and also the potential restriction of airspace due to the increased use of UAV's proposed in the UK :*

This has far more to do with finance and control rather than air safety.

Charging for VFR flight by reference to Mode S is a myth, presumably started because facts are too hard to come by.

Sharing airspace with other users (CAT/UAVs) is surely preferable to more R/P or CAS, is it not?

Safety advantage..... not from the CAA !
 

As some one who has Mode S in one of my aircraft I can tell you that it provides no safety advantage what so ever at the moment there are only two radar heads that can use Mode S, in short if a low powered Mode S transponder is not within 30 miles or so of these radar heads it can't be "seen".
The safety advantage of mode would be WX and traffic data link this system would give light aircraft a a WX radar picture and a TCAS like system but have NATS/CAA mandated the instalation of the ground based equipment for these systems ? like hell have they.
Untill the authoritys start to install the data linking of these safety systems the argument that Mode S is a safety mandate is bankrupt.
So far the mode S thing seems to be driven by a need for some parts of the CAA to to keep them selfs in a job, once they have the Mode S thing in the bag they will form another commitee to spend two years "consulting" to force another bit of usless kit on light aviation to protect CAA jobs.

Tangovictor you are sadly mis informed the CAA won't be installing the kit to keep you clear of the military fast movers!

Just as well, as I'd expect the RAF/RN to be paying for it - which they are.

There has never been a mid air collision involving GA which would have been prevented by Mode S.

Rod1

Rustle
 

I don't see any one installing traffic data link........... Do you ?

RAF types are fitting Mode S / TCAS.

Them avoiding hitting you (because they see you on TCAS) saves as much pain as you avoiding hitting them ;)

TCAS would enable them to see (AND AVOID) Mode S targets.

Catchy, but untrue.

The Tornado/Cessna crash (killing 4) would have been avoided if the FJ had TCAS and the Cessna had Mode S.

Or if the fast jet had had TCAS, and the Cessna had been squawking Mode C.

Mode S gives no improvement over Mode C for that purpose.

Of course that is correct, and highlights one of the dangers of discussing these things in isolation.

So it would have been avoided by TCAS and mode C then? Where does the mode S bit come into that Rustle?



opps....crossed posts

There are very few GA mid air collisions. All would have been less likely if TCAS was fitted to one or both aircraft; Mode s (instead of mode c) would have made no difference. The Tornado / C152 incident would have been avoided if the Tornado had had TCAS.

The CAA proposal makes mode S compulsory, not radio or TCAS, and our most likely mid air is with other GA traffic.

The RAF are fitting TCAS to some of its fleet, but the time frame if many years and it is starting with the large transport types. Stay above 2000 ft AGL and your chances of meeting the RAF in the open FIR are insignificant.

Rod1

Yes the RAF have fited TCAS and this is a big improvement in safety but the whole point of this thread is about the mandating of Mode S and the supposed safety improvments that the CAA is using as a reason for pushing this along.

So far the CAA has failed spectacularly to prove it's safety case for Mode S above Mode C, the safety issue is just a smoke screen to cover the issue that this implimentation is just jobs for the boys at the CAA.

If the safety was the real issue at the CAA then we would have the WX & traffic data link installed, this would bring TCAS like indications within the reach of most light aircraft.

The mode S issue would be a lot less of a hot potato if the issue was one of safety and it was being introduced with some improvement to GA safety but it is not of any improvment what so ever over Mode C.

"The Tornado/Cessna crash (killing 4) would have been avoided if the FJ had TCAS and the Cessna had Mode S."

Clearly you dont understand the difference between mode S and mode C.

NATS is a service provider, totally divorced from the CAA, and not the regulator. So it's not up to them to mandate the ground based equipment.

NATS would only fit the ground based kit you talk of for one of two reasons. Either they see a benefit to their service provision (and have the users pay for it through navigation charges), in which case they would have to convince the CAA that the kit they were putting in met safety and regulatory standards, or the CAA decide that providers like NATS must have such equipment as part of their 'licence' to provide ATC services and provide the system specifications.

Neither has happened to date and the former is unlikely to happen with NATS under pressure from the CAA to reduce costs and not increase them. You'll need to lobby ICAO, the European Commission, or the CAA, if you want to push through such a requirement for compulsory ground based equipment. Good luck !!!

Check out the PFA's response letter http://www.pfanet.co.uk/Consultation...er%20Final.pdf It explains the objections far better than I can.

SS

As far as I am aware the RAF/MOD are only fitting TCAS to transport types. Fast Jets will get a Collision Warning System. They cannot be given TCAS because the TCAS logic can't cope with fast high performance pointy-things.
So why aren't the CAA getting NATS to fully equip before insisting on mandatory equippage?

There is an improvement to GA safety. "GA" becomes visible on TCAS so is less likely to be involved in a collision.

Mode S has been talked about for YEARS. If, instead of carrying out ridiculous RIAs the CAA had simply mandated it WEF 03/2005 for IFR and WEF 03/2008 for everything else, the absurd situation of people fitting mode A only transponders (just in case) would never have arisen.

Someone would have spent their R&D budget making a small battery operated transponder that no-electrics-aircraft could use. A market would exist, and necessity is the mother of invention.

Regarding the RAF TCAS/Mode S - they are fitting the Tucanos currently, and the Tornados shortly, neither of which is "transport category" AFAIK.

What advantages does mode S have over mode C so far as TCAS is concerned?

You'd have to ask the CAA, but my guess is because it has not been asked for as part of the requirements placed on countries who have signed up to the European Mode S programme. If the CAA were to place the requirement on UK ATC providers, then those providers could quite understandably ask why the UK CAA is placing a more onerous requirement on them than Europe is asking for, as well as asking how it is to all be paid for.

The European policy can be found here. It solely addresses ATC issues and has not been formulated with a view to providing airspace users with add ons.

Eurocontrol Mode S Policy

Why not ?? Probably because no body or organisation with influence in the user community has asked for it, or put forward proposals for how it would operate and be funded. Maybe that's the problem without not having a powerful body who can speak on behalf of us all when it comes to political decision making on an international basis ? Nor one which can take on the views of a wide diverse group of operators and pilots.

So as far as equipping GA/light aircraft/gliders etc is concerned, is the CAA mandate in line with the rest of Europe or are UK operators being asked to meet a more onerous requirement?

UK would fall in line with the stated policy I would wager. It's the way Brits do things :)

Only that it addresses the frequency congestion issue -- more likely if we all use only Mode C that TCAS gets confused.

In the CAA response document, there did seem to be hope of significant exemptions for aircraft already equipped with Mode A/C.

but with TCAS in normal mode isnt the "bubble" less than 3,000 feet? In what way does traffic congestion reduce the benefits of TCAS whether surrounding aircraft are mode c or s. Presumably the amount of congestion would have to be unbelievably great or presumably the "filters" cant cope?

Does TCAS use selective mode at all when actively polling?

I don't think it does. A Mode C responder is probably exactly the same as a Mode S one.

It's only when one starts implementing ADS-B over the Mode S data channel (I forget the terminology; "extended squitter"?) that there is a difference in the TCAS context. But ADS-B is many years away, in these parts.

I've asked the question of someone who knows and will post again when I get an answer.

However, to my simple mind it would make sense that where there was a gaggle of responses such as might be found when a bunch of gliders are thermalling together, TCAS would get better resolution were it to interrogate each individually (selectively) rather than the mode A/C response which is to talk whenever a question is asked. ;) (Of course these individual interrogations happen very quickly in human terms.)

NATS is most of the way through its rolling programme of replacing its radar heads with ones capable of Mode S. NATS ATC Terminal Control centre at West Drayton uses Mode S.

BD

So, is the rest of Europe 'designating' on a national basis all airspace as Mode S airspace, or is it only the UK?

The UK goverment has asked industry to come up with L.A.S.T. Lightweight Aviation SSR Transponder. A Google will show you lots of models specifically for the glider, balloon and microlight end of the market :)

BD

TCAS would get better resolution were it to interrogate each individually

This sort of issue arises in other kinds of communication (e.g. ethernet) and is sorted out pretty well by randomising the delay before responding, etc.

I am sure it's sorted already; there can easily be as many planes in a holding stack, and nearby, as there might be gliders in close proximity.

I think a useful Q to ask about the claimed need for selective interrogation of Mode S is why the USA doesn't have problems with Mode C. I am see the Mode S advantages to ATC in terms of software features (I saw some demos at NATS) which are probably more robustly implemented with S than with C but these are not being presented as the primary case.

Yeah, I sorta know how ethernet manages :)

AFAIK Mode A/C doesn't randomise anything - it certainly doesn't rely on CSMA/CD: If interrogated, it squawks.

WRT gliders in close proximity - my understanding from posts here and elsewhere is that they circle a lot closer together than the 1000' vertical sep and 4 minute holds at 180/250 KIAS achieved by CAT in the stack. ;)

In a competition, maybe 30 or so gliders with 200 ft horizontal and 100ft vertical separation.

A previous poster mentioned "lots" of Mode S transponders aimed at the glider etc. market. Last time I searched in late December there were 2 announced, neither actually for sale or with prices fixed and with no indication of the certification and other costs. Forgive me for skepticism on this one.

IO, I have asked that question as well - of the CAA presenter at one of their roadshows. His answer basically was 'well our analysis says there will be a problem don't know about theirs'. I am pretty convinced that the CAA has rigged the scenario (maybe assumed all air users are transponding Mode C - an unrealistic scenario because gliders, microlights, hang gliders, etc. need new technology to be transponding and it will be Mode S or ADS-B) to prove their case as the amount of traffic in the NY TRACON with its Mode C veil is more than the UK and their system works!
I am pretty sure TCAS units do a periodic Mode S 'All Call' to get who it is interested in and then selectively interrogates. All of the Mode S transponders respond to the All Call and to their individual request and all of the Mode A/C ones respond to all requests (much more noise)
Having random response times won't work for two reasons. 1 - the range is determined using the time delay from transmit to receive and knowing that the response delay is a constant number, 2 - All of the responses are 'randomised' in the sense that the round trip distance from the interrogator to the receiver is different for each aircraft. The noise problem is when you receive a response from someone else's interrogation that is close in time to the one you wanted.

The only people that have benefited from the Mode S is the spotter with these SBS :yuk: things. It has made there 'hobby' a lot easier:}

The French are fully complying with the Mode S situation by handing out exceptions like confetti. Most of the GA is likely to get excluded, some, for example 8000 ULM’s, have already got it. As things stand these aircraft will be able to visit the UK.

Rod1

"If, instead of carrying out ridiculous RIAs the CAA had simply mandated it WEF 03/2005 for IFR and WEF 03/2008 for everything else, the absurd situation of people fitting mode A only transponders (just in case) would never have arisen."

I am very glad they did (conduct a RIA that is) - the more I read the comments of those who understand the technoloy, the way we and other member states seem to be intending to implement mode S and its apparent lack of benefits over mode C the more convinced I become that it is a disaster in the making.. .. ..

Especially when only 1% of the respondents support the proposal.

I am not a fan of the way the CAA has approached mode S and find some of the views that broadly can be characterised as "You must fit Mode S because it is good for the system but if you want anything like TIS or FIS you must pay" to be morally lopsided - where I need to spend for someone else's gain but have no reciprocal spending on me.

HOWEVER, transponding with altitude data without doubt increases safety in the system. People with Mode C/S are much less likely to be involved in an airprox or an infringement that has real safety risk (because there are much better odds that the other guy will avoid you). It is true that transponders don't address the risk of two VFR aircraft not receiving a service colliding with each other - but both of those aircraft have made the choice to not avail themselves of any assistance from ATC or technology. I remain stunned that high volumes of traffic - which have no technical reason not to squawk Mode C - are allowed to operate under and adjacent to the TMAs and class D zones. Everyone who has a generator onboard and has invested in any level of avionics should have and use a Mode C/S transponder.

The current approach of trying to mandate more technology than I believe is warranted (Mode S vs. Mode C) and pretending there are viable solutions for no-electric aircraft is daft. But, the guys flying without generators should be aware, a worryingly high level of infringements with serious collision risk involve gliders, microlights, aerobating aircraft - its not just the spam cans involved in the collision risk problem.

"HOWEVER, transponding with altitude data without doubt increases safety in the system."

I very much agree.

It is the justification for compelling aircraft with perfectly good mode C transponders to replace them with mode S transponders which seem to offer few, if any, benefits that I question.

Well, we've done this one to death so many times :)

I think that if Mode C was made mandatory years ago, there would be little pressure now for Mode S; one would have TCAS working properly and that would defuse the main driver behind the current business (safety for CAT), etc.