Mode S petition at No 10

[stickandrudderman]

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.

[tangovictor]

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 ?

[javelin]

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.

[rustle]

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 :*

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?

[A and C]

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!

[rustle]

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.

[Rod1]

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

Rod1

[A and C]

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

[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.

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

Catchy, but untrue.

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

[robin]

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.

[rustle]

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.

[dublinpilot]

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

[Rod1]

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

[A and C]

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.

[Fuji Abound]

"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.

[PPRuNe Radar]

have NATS/CAA mandated the instalation of the ground based equipment for these systems ? like hell have they.

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 !!!

[shortstripper]

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

SS

[Single Spey]

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.

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.
NATS would only fit the ground based kit you talk of for one of two reasons. Either ... 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.

So why aren't the CAA getting NATS to fully equip before insisting on mandatory equippage?

[rustle]

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.

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.

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.

[Fuji Abound]

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

[PPRuNe Radar]

So why aren't the CAA getting NATS to fully equip before insisting on mandatory equippage?

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 (http://www.eurocontrol.int/msa/public/standard_page/modes_policy_imp.html)

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.

[Single Spey]

. 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.
.

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?

[PPRuNe Radar]

Mode S Elementary Surveillance (ELS) Implementation Timescales

IFR Airborne Implementation


For aircraft flying IFR as General Air Traffic (GAT), the latest dates for the carriage and operation of Mode S ELS airborne equipment in designated airspace are as follows;

New production aircraft to be compliant by 31 March 2007.
Completion of aircraft retrofits by 31 March 2007.


VFR Airborne Implementation


All aircraft flying VFR in designated airspace are required to carry and operate Mode S ELS airborne equipment by 31 March 2005 with the following Transition Period:

New production aircraft to be compliant by 31 March 2005, although there is now a general relaxation until 31 March 2008.

Completion of retrofits, irrespective of date of first CoA issue, by 31 March 2008.


Mode S Enhanced Surveillance (EHS) Implementation Timescales


The requirements of Mode S EHS apply to IFR flights as GAT by fixed wing aircraft (having a maximum take-off mass greater than 5,700 kg or a maximum cruising true airspeed in excess of 250kt) in the designated airspace notified by:

Germany and the United Kingdom with effect from 31 March 2005, and France with effect from 31 March 2007.


A transition period of 2 years will be applied until 30 March 2007, during which a coordinated exemption policy will be applied through the EUROCONTROL Mode S Exemption Coordination Cell.

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

[bookworm]

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

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.

[Fuji Abound]

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?

[IO540]

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.

[rustle]

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.

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.)

[BDiONU]

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 !!!
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

[Single Spey]

For aircraft flying IFR as General Air Traffic (GAT), the latest dates for the carriage and operation of Mode S ELS airborne equipment in designated airspace are ...

VFR Airborne Implementation

All aircraft flying VFR in designated airspace ...

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

[BDiONU]

what isn't fine is the fact that there are no cheap, battery operated versions available for non electric aeroplanes - gliders etc.

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

[IO540]

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.

[rustle]

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. ;)

[ProfChrisReed]

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.

[mm_flynn]

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.
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!

Does TCAS use selective mode at all when actively polling?
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.

[L-Band]

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:}

[Rod1]

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

[Fuji Abound]

"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.

[mm_flynn]

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.. .. ..


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.

[Fuji Abound]

"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.

[IO540]

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.

[Rod1]

MM, You must fly in a very different part of the world to me. Most PPL’s fly at the weekend, so almost no military traffic and almost no LARS.

“People with Mode C/S are much less likely to be involved in an airprox or an infringement that has real safety risk”

The chances of me meeting anything other than another GA aircraft at 2000 ft on a Saturday in the open FIR are zero.

“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.”

What ATC assistance? I can just about squeeze a flight information service, if I am lucky, from say East Mids, but on a busy Saturday there is no LARS for 90% of the UK and even EMA will often tell you to standby for so long you are out of the area by the time you get a response, which is of very limited value for collision avoidance. I would have no problem with carrying mode c or even mode s if it had any benefit whatsoever, but it does not. I accept that the IR pilots will gain benefit, but VFR outside controlled airspace which is 95% of that most PPL’s do, it has no value.

Rod1

[mm_flynn]

Rod1,

Flying in the SE I generally find I can get something out of ATC, if I ask. Could it be a lot better? - of course, but ATC can also provide a lot better information with less work if they are calling relevant mode c traffic vs various mode A and non-transponding possible targets.

For people who fly in the truely open FIR off grass fields no where near controlled airspace then the value of a transponder is low - but I would have thought these people are not going to have invested very much in avionics (1 radio and a hand held GPS maybe) given that they are not going to be going very far - and my arguement for installing Mode C isn't directed at this type of flying. Once you plan on going somewhere you are going to be mixing with people who are getting a service and are carrying technology to detect you (even if it is very basic with just a range, relative altitude and maybe rough bearing)

[Rod1]

MM

I think you are underestimating the PFA flyers. Over 1000 of them do not have a radio let alone a transponder, but regular trips the length of the country are flown using traditional navigation. The infringement profile for such aircraft is better than the average club spamcan, according to the PFA, and most do remain well clear of CAS. There was an article about an open cockpit single seater which was flown from the north of Scotland to Kemble with maps, stopwatch and a hand held radio, which is just one example. The BMAA members do similar trips in similar aircraft.

I had an aerobatic single seater for a while, it had no electrical system and flying it around relying using traditional navigation techniques was huge fun and surprisingly accurate.

The CAA proposal was for all aircraft to be fitted with mode S. Work done by the PFA on the likely range of a LAST style device in the cockpit of a typical PFA aircraft using an internal aerial showed the range for reliable detection was very very low and the radiation levels for the pilot to be above EU HAS regs. The result of this work is that large numbers of aircraft will gain exemptions, others, hopefully, will be allowed to carry on with mode c, and some will have to fit mode s.

The CAA have announced that another consultation is to be carried out, so the implementation dates are likely to slip, even if you do end up in a group which has to fit one.

Rod1

[rustle]

If, for argument's sake, there are these exemptions from compulsory Mode S (or any transponder for that matter), will that not be a bit of a hollow victory once N/K/U becomes reality?

The BGA have had to accept the change to FL195 and above becoming "C", and have I assume gained some dispensation in areas where they routinely use airspace above FL195.

It is unrealistic to believe that the "south-east of England"* will ever be anything other then N or K, probably from the ground up (or at "best" using the Netherlands model of 1200' and upwards) [NB The Netherlands model is never mentioned in the PFA document: Only France and their laissez faire attitude to regulations :}]

No transponder, no entry to N or K.

* south-east of England would encompass an awful lot of airspace, certainly larger (and lower) than the existing (L)TMA.

IMHO there's an awful lot of intelligent people spending a lot of time arguing about the inevitable... ;)

[mm_flynn]

MM
I think you are underestimating the PFA flyers. Over 1000 of them do not have a radio let alone a transponder, but regular trips the length of the country are flown using traditional navigation. The infringement profile for such aircraft is better than the average club spamcan, according to the PFA, and most do remain well clear of CAS. There was an article about an open cockpit single seater which was flown from the north of Scotland to Kemble with maps, stopwatch and a hand held radio, which is just one example. The BMAA members do similar trips in similar aircraft.

I am not in any way advocating the installation of technically impractical devices (i.e. LAST with internal antenna), but people who are transiting the length of the country are going to interact with people who are getting ATC services or able to detect transponders. Using Mode C/S, where practical, would increase safety. Non-transponding 'PFA' types do figure significantly in high risk loss of separation incidents. While they may infringe less often, the lack of Mode C data means the infringement is more likely to be a serious risk.


Rustle,
While I broadly agree with your point, I doubt mandatory transponders in Class G will be implemented irrespective of the limits of technology - which are real. The CAA position is faintly ridiculous in that taken literally it would ground gliders, micro lights, parachuting, etc. Even the CAA in the RIA concedes there would have to be exemptions for those users for whom current transponder technology is impractical.


Ultimately we will all have some sort of device to be electronically visible and that is good. But in the short run, The CAA approach is getting backs up, possibly discouraging the use/installation of Mode C (which is pretty cheap as people equip for Mode S) and driving a cost that, RF pollution aside, adds nothing in class G beyond Mode C (which I am a keen supporter of)

[Fuji Abound]

"spending a lot of time arguing about the inevitable"

"Inevitable" and a support level of 1% just dont seem to go hand in hand :confused:

If they do then democracy has truly failed us all.

[bookworm]

"Inevitable" and a support level of 1% just dont seem to go hand in hand :confused:
If they do then democracy has truly failed us all.

Oh come on. The support level for Christmas amongst turkeys is even less than 1%. It remains somewhat inevitable. ;)

[dublinpilot]

Oh come on. The support level for Christmas amongst turkeys is even less than 1%. It remains somewhat inevitable. ;)

United Kingdom of Turkeys? :}

When did turkeys become citizens and get a vote anyway?:eek:

[Rod1]

The French think it is inevitable, but it does not apply to them. This sort of inevitable is fine by me. Even if the CAA tries to force it through, the level of opposition and the technical errors in the plan will lead to lots of delay.

Rod1

[dublinpilot]

Things that are inevitable, but grossly unpopular, and virtually impossible for large sections of the community to comply with, have a way of becoming avoidable when politicians start to get asked awkard questions in public.

[Fuji Abound]

I am old enough to remember those who said the poll tax was inevitable.

Of course, they were correct!

A few wished they hadnt been, and a few wished they had listened and gone about it differently.

[rustle]

Things that are inevitable, but grossly unpopular, and virtually impossible for large sections of the community to comply with, have a way of becoming avoidable when politicians start to get asked awkard questions in public.

Yep, you're right.

God forbid anyone asks a politician "how come my trip home from Ibeefa to Durham goes through a load of uncontrolled airspace and the pilot reckons he's got no idea who else is out there? How can that be allowed? and I heard loadsa stuff nearly hits each other around there. summit should be dun abaatit"

Or

"'ow come my mate reckons he was on a EasyAir special £1 flight into Stanstead [sic] and he reckoned he saw some bloke wiv a lawnmower engine on his back out the winda nearly 'it 'em!!??"


Good luck ;)

[Single Spey]

Yep, you're right.

God forbid anyone asks a politician "how come my trip home from Ibeefa to Durham goes through a load of uncontrolled airspace and the pilot reckons he's got no idea who else is out there? How can that be allowed? and I heard loadsa stuff nearly hits each other around there. summit should be dun abaatit"



"OK Sir, it can't be allowed so we shall just pull the route licences from the airlines flying from Durham so I'm afraid you'll have to go to Manchester next time you wish to go to Ibeefa"

Or

"Would sir accept this as a compromise, after all you have no more right to airspace and to be flying around than anyone else?":ok:

[shortstripper]

God forbid anyone asks a politician "how come my trip home from Ibeefa to Durham goes through a load of uncontrolled airspace and the pilot reckons he's got no idea who else is out there? How can that be allowed? and I heard loadsa stuff nearly hits each other around there. summit should be dun abaatit"


And God forbid the politician who admits that commercial passenger jets now routinely fly in class G on the basis that it saves them money and are protected by nothing more than budget devices with iffy effect!

SS

[rustle]

I think we all know what would really happen. Especially as the same problems affect Newcastle too. ;)


SS not sure what you are suggesting are "budget devices with iffy effect" :confused:

[shortstripper]

Low powered portable devices with probably a very short range in TCAS terms. Opps! 747 at 400mph, PFA type at 100mph and maybe a 2 mile range? Hmmmmm

SS

[Fuji Abound]

"Yep, you're right.

God forbid anyone asks a politician "how come my trip home from Ibeefa to Durham goes through a load of uncontrolled airspace and the pilot reckons he's got no idea who else is out there? How can that be allowed? and I heard loadsa stuff nearly hits each other around there. summit should be dun abaatit"

Or

"'ow come my mate reckons he was on a EasyAir special £1 flight into Stanstead [sic] and he reckoned he saw some bloke wiv a lawnmower engine on his back out the winda nearly 'it 'em!!??""

That is about the most ridiculous comment I have read on these forums in a very long time.

Next you will want the Turkeys fitted with mode S - after all you know they make a nasty mess of the hot section. :D

[Lucy Lastic]

Yep, you're right.

God forbid anyone asks a politician "how come my trip home from Ibeefa to Durham goes through a load of uncontrolled airspace and the pilot reckons he's got no idea who else is out there? How can that be allowed? and I heard loadsa stuff nearly hits each other around there. summit should be dun abaatit"

Or

"'ow come my mate reckons he was on a EasyAir special £1 flight into Stanstead [sic] and he reckoned he saw some bloke wiv a lawnmower engine on his back out the winda nearly 'it 'em!!??"


Good luck ;)

In my experience of flying Chavair, the shell-suited self-loading freight is pretty much comatose to bother about looking out of the window, or even to be capable of seeing another 737.

They aren't looking for, or are capable of seeing anything out of the window.:=

[rustle]

In my experience of flying Chavair, the shell-suited self-loading freight is pretty much comatose to bother about looking out of the window, or even to be capable of seeing another 737.

They aren't looking for, or are capable of seeing anything out of the window.:=

They'll notice when the £8.50 Bacardi Breezer they just bought is spilt when the pilot is forced to take last-minute avoiding action. ;)

The CAA will notice, too.

These two:

airprox 1 (http://www.caa.co.uk/application.aspx?categoryid=14&pagetype=65&applicationid=7&newstype=a&mode=detail&nid=1367)
and
airprox 2 (http://www.caa.co.uk/application.aspx?categoryid=14&pagetype=65&applicationid=7&newstype=a&mode=detail&nid=1348)

in only the last three months of 2006 keep them awake at night wondering if transponders and TCAS or CAS would have helped avoid them.

The airprox archive is full of these. (Which is better than the AAIB being full of them, granted.)

This radar replay (http://www.flyontrack.co.uk/radar.asp) is also worth a look.

[Lucy Lastic]

Rustle

Are you sure these items actually support your argument. Going through the list of airprox reports they are almost exclusively commercial traffic or military.

There is the one mention of a civil helicopter but no idea as to the type, or a multi-engined civil type. Certainly, it would appear from the limited information contained in thereports, that each aircraft was likely to be carrying the full complement of avionics, yet still was involved in an airprox.

Looking at the airproxes on the list there is no instance of a glider, PFA-type, microlight or paramotor having an airprox, mainly because there is a natural separation.

If Mode S (or Mode C) and TCAS was such a great idea, how come these incidents happened?

[mm_flynn]

LL you are right that the two links provided re the airproxes don't really illuminate this argument, as there are very few facts. You are also right that most airproxes are between transponding aircraft. When I have read the details I wind up with the impression that for some commercial pilots, if their TCAS shows less than minimum IFR separation they file an airprox - even though they are operating in VMC, and in Class G.

HOWEVER, the last link shows exactly what rustle is banging on about, a spam can only Mode A operating right in the approach path inside CAS, but the controller only realises it when the infringing aircraft enters the zone! all a bit too late!

Mode C/S transponding helps a lot but is only part of the answer as demonstrated in Brazil last year when two TCAS equipped aircraft, with mode S, under positive control, in controlled airspace at fl360 hit each other!

[rustle]

LL you are right that the two links provided re the airproxes don't really illuminate this argument, as there are very few facts. You are also right that most airproxes are between transponding aircraft.
...
HOWEVER, the last link shows exactly what rustle is banging on about, a spam can only Mode A operating right in the approach path inside CAS, but the controller only realises it when the infringing aircraft enters the zone! all a bit too late!

Mode C/S transponding helps a lot but is only part of the answer as demonstrated in Brazil last year when two TCAS equipped aircraft, with mode S, under positive control, in controlled airspace at fl360 hit each other!

Actually the two airprox links do illustrate my point, albeit in a roundabout way.

TCAS is the last line of defence. For CAT in CAS it shouldn't ever be needed: But it is. In simple terms the difference between some aircraft featuring in airprox reports and AAIB reports is TCAS.

The two I linked were from the period Sept-Dec 2006, and were the only two in that period that were not CAT/CAT or CAT/MIL.

The Brazil accident (discussed in a lot of detail elsewhere on here) appears to have been down to a number of factors, one of which was an insidious "failure" of a transponder thereby taking TCAS out of the safety net. It is fair to speculate that had the transponder not "failed", TCAS would actually have assisted in preventing the collision despite everything else.


The last link (radar replay) was the Stansted one. (One of many that could have been shown). The controller in that instance never knew the intruder was inside CAS until after the event when the intruder spoke to another agency and declared his altitude and that he was "lost". The inbound CAT and the intruder never saw each other, either.

[Lucy Lastic]

The Brazil accident (discussed in a lot of detail elsewhere on here) appears to have been down to a number of factors, one of which was an insidious "failure" of a transponder thereby taking TCAS out of the safety net. It is fair to speculate that had the transponder not "failed", TCAS would actually have assisted in preventing the collision despite everything else.


Sorry, it must be too early in the morning.

What you are saying here is that TCAS would have worked if the transponder hadn't failed (as some may do, from time to time). Are you then going to suggest that we should carry more than one just in case?;)

[Fuji Abound]

I thought the controller is required to provide 5 nm lateral from unknown traffic and 5,000 feet from unverified mode C? Presumably in this case he did. What information was available from primary radar? Presumably the CT got a TA assuming traffic within 1,200 feet as no mode C.

The suggestion is the “trigger” for the Brazil accident was the automatic updating system used by AT and not the failure of the transponder.

What these incidents actually show is that if all “aircraft” were fitted with TCAS and mode C and neither mode C or TCAS could be turned off by the pilot then one mid air collision in 100 years might be avoided (or something like that number).

The reality is if light aircraft were required to fit TCAS and mode S there wouldn’t be any left flying - which I suppose would solve the problem. The proposal is that they fit mode S, but what evidence is there this provides any advantages over mode C? Mode C is visible to AT, mode C is visible to TCAS (should you have it). It does not provide TCAS interoperability unless both aircraft have mode S and TCAS, but is there any evidence that increases safety between light aircraft and CT in situations a conflict is likely to occur? The “argument” is that mode C suffers in high traffic situations - but is there any evidence to show in likely situations of conflict this is a problem? The proposal might well have been that all aircraft should at least be fitted with mode C (the units are relatively cheap, and readily available) but it wasn’t.

[rustle]

I thought the controller is required to provide 5 nm lateral from unknown traffic and 5,000 feet from unverified mode C? Presumably in this case he did. What information was available from primary radar? Presumably the CT got a TA assuming traffic within 1,200 feet as no mode C.

If you look at the airspace in question you will see that the base of CAS is 1500' -- a "stub". Something not known to be in the CAS-stub is deemed beneath it: That's the rule. No separation would have been applied at all, as the intruder was deemed OCAS. Period.

...Are you then going to suggest that we should carry more than one just in case?

GA? No. ;)

[mm_flynn]

The last link (radar replay) was the Stansted one. ( I do need to read:* I thought it was replay 1. But all the comments are still relevant.

My point on raising the Brazil incident was that any system CAN fail and transponder/TCAS as the primary tool is not a good idea. However, there are many errors in the system for which TCAS/transponder provides a safety net, e.g Level bust, infringement, controller error, emergency deviation from cleared flight path, radio failure, not seeing each other in VMC, etc.


Fuji - I am very firmly in the altitude transponders are good camp (for those who are technically capable of carrying them), but agree wholeheartedly that Mode S elementary (which is what we are talking about) vs. Mode C has a very very marginal safety case.

[Fuji Abound]

"If you look at the airspace in question you will see that the base of CAS is 1500' -- a "stub". Something not known to be in the CAS-stub is deemed beneath it: That's the rule. No separation would have been applied at all, as the intruder was deemed OCAS. Period."

I did (look at the airspace).

However, the controller didnt know the aircraft was in OCAS because the mode C was unverified.

Does the controller simply assume in these circumstances the aircraft is within the required 1,000 feet of airspace? What about primary radar? Would the CT have received a TA? Presumably in the absence of mode C the CT assumed the aircraft was within OCAS?

.. .. .. and so I am still interested in evidence that mode S, as opposed to mode C, offers any better collision avoidance protection, and if so why - which appears to be some of the thrust for the compulsory fit of mode S.

[rustle]

However, the controller didnt know the aircraft was in OCAS because the mode C was unverified.

Does the controller simply assume in these circumstances the aircraft is within the required 1,000 feet of airspace? What about primary radar? Would the CT have received a TA? Presumably in the absence of mode C the CT assumed the aircraft was within OCAS?

I really think you ought to read it again: The orange/brown NMS shows 'No Mode S' information available, but in fact, it is the lack of 'Mode C' which is important here. In fact, the pilot of this aircraft is 'unsure of position' but hasn't told anyone (yet). The controller therefore takes the '7000' squawker (which has not at this stage declared he is lost) as being UNDER 1500'.

It isn't a case of unverified Mode C, it is a case of no mode C, 7000 VFR, being where he shouldn't have been.

The traffic would probably have appeared on the TCAS of the CAT in yellow with no height information. No audible TA (traffic, traffic) call would happen as there's no way of deducing proximity. Safely ensconced in CAS, talking to ATC, there would be no problem as far as the CAT was concerned.

---

Mike, I think the thrust of the S -v- C point is based on the premise that:

1. Everything should be squawking C (I think there is almost consensus here);
2. If everything is squawking C there is saturation and errors in ground-based equipment: I cannot remember the terms used but things like garbling and fruiting are often mentioned.

At first glance it looks like (2) isn't an issue, and with today's output it might not be. But if you look at it from the perspective of (1) being "fact" then (2) follows, and for the benefits to be realised some "selectivity" of response/responders is required.

[Fuji Abound]

"I really think you ought to read it again: "

There is no excuse for busting CAS. I am not defending the aircraft or the illustrative purpose of the radar tape.

I was simply expressing surprise that when an unidentified aircraft crosses the localiser below the base of CAS it is assumed he is in OCAS. If that is the case so be it.

However, if he was in CAS and mode C but a faulty encoder indicated he was in OCAS, is the same assumption made. If so what help is mode C?

On other threads, I seem to recall contollers bemoaning aircraft who transit beneath the stub and beneath the localiser without communicating because whilst they are entitled to do so the controller will often break off approaches in consequence.

I was simply trying to understand whether there remains any safety net in these circumstances?

[rustle]

I was simply expressing surprise that when an unidentified aircraft crosses the localiser below the base of CAS it is assumed he is in OCAS. If that is the case so be it.

However, if he was in CAS and mode C but a faulty encoder indicated he was in OCAS, is the same assumption made. If so what help is mode C?

Forget the SS stub for a minute and think about the LTMA where the base is 2500'. If everything underneath that couldn't be "deemed" OCAS (unless it was indicating >2500 or sighted inside CAS) where would that leave us?

If something is squawking C and that indicates it is inside CAS (verified or not, faulty or not) it will be separated by ATC (certainly be passed as "aircraft in your x-o'clock, indicating zz, unverified"), and TCAS will avoid it.

I'm sure one of the controllers on here can clarify.

On other threads, I seem to recall controllers bemoaning aircraft who transit beneath the stub and beneath the localiser without communicating because whilst they are entitled to do so the controller will often break off approaches in consequence.

I was simply trying to understand whether there remains any safety net in these circumstances?

The other threads you refer to prob95 relate to people transiting and/or hanging-about around the IA path at airports without the protection of CAS.

Cranfield/Biggin/Farnborough are good examples of this, where despite the chevrons on the 1:500, because it is class G people are there.

Airmanship would dictate that isn't sensible.

[IO540]

It may not be sensible but it is Class G.

If you dig out all the plates for say Biggin; IAPs, SIDs (called SDRs pedantically, before somebody jumps on me) etc plus the radar vectors onto the Biggin ILS which Thames Radar might give you, Biggin is completely surrounded for many square miles around with potential IFR traffic routes.

The single FAT symbol on the 1:500k chart gives little indication of all this potential activity, so I wonder why the CAA puts it on there at all.

The assumption that non-C/S traffic within CAS that doesn't meet the ground is below the CAS is the only way ATC can work the system, but it is an obviously dodgy assumption. So far, it has worked through pure luck. Compared with all the super strict rules operated by ATC, this is a bit like having a tunnel leading straight into the Bank of England vault from the street outside and hope that nobody notices it.

[zkdli]

Not sure why people think that it is dodgy for controllers to ignore aircraft that are operating outside of CAS?

We all operate with the presumption that we know what each other is doing. If a controller sees an aircraft squawking 7000 that does not have mode "C", he is entitled to expect that the pilot knows where he is and is not going to be in CAS with out a clearance!

If you are saying that this is not the case, are controllers expected to assume that all pilots flying aircraft on 7000 squawks do not no what they are doing and should avoid them on the off chance that they are in CAS?

Sounds like a good argument for mandatory altitude encoding transponders and regulating that they are on at all times - isn't that why we are having this problem with mode "S"...:)

[rustle]

It may not be sensible but it is Class G.
...
The single FAT symbol on the 1:500k chart gives little indication of all this potential activity, so I wonder why the CAA puts it on there at all.

"It may not be sensible but it is class G" is why we end up with class D+ ;)

As anyone who's studied air law rather than just passed the exam knows (not aimed at anyone in particular), the chevron on the 1:500k used to be aligned with the most likely IA*, but its presence on the chart meant that there would probably be instrument traffic "in the vicinity": Situational awareness without even having to speak to anyone or look out the window :)

(* AFAIK this was changed so that both/all instrument runways are so marked if possible and not too cluttered)

Anyhoo, all this is miles away from some petition asking TB to wade into the Mode S discussion...

[pulse1]

I have received another letter from Gillian Merron, Undersecretary of State, Department of Transportation.

For information she says that the DAP have received more than 3000 responses to the consultation and that the analysis "is expected to take some time yet".

She also says that the DAP, in consultation with the Goverment, "will then make a judgement as to whether a further stage of public consultation will be beneficial.
Irrespective of this additional consultation with representatives from different sectors of the aviation community will take place during this period as appropriate".

From this it would seem appropriate to lobby whoever represents your aviation interests so that they are left in no doubt about how to respond at this further consultation.

[PPRuNe Radar]

We all operate with the presumption that we know what each other is doing. If a controller sees an aircraft squawking 7000 that does not have mode "C", he is entitled to expect that the pilot knows where he is and is not going to be in CAS with out a clearance!

If you are saying that this is not the case, are controllers expected to assume that all pilots flying aircraft on 7000 squawks do not no what they are doing and should avoid them on the off chance that they are in CAS?

Sounds like a good argument for mandatory altitude encoding transponders and regulating that they are on at all times - isn't that why we are having this problem with mode "S"...

Well said :)

If we were enforced to avoid all 7000 squawks just in case they were inside CAS, then we'd need to do the same with all our traffic operating above FL245 as well (FL195 in March). I think the situation would last about 1 day before the political pressure to change back to what we have today, or enforce everyone to have Mode C, would be brought to bear by the airlines and the military ;)