Proposed amendment of the ANO: Mode S

[avidflyer]

I've just returned from the consultation meeting at Barton and put to the technical chap there (sorry, forgot the name) a proposal very similar to Beagle's. He agreed it would be an effective interim solution if you assume that existing Mode C transponders would all be replaced gradually so extending the 1090MHz saturation deadline past the date at which Mode C would have disappeared (no timescale given though). Interestingly, he said there had been the same solution proposed at Lasham.

[Aunt Rimmer]

There will also be no way for one controller (Approach) to know that the Mode C is verified (by Zone for example) unless they pass traffic information and maintain track identity.

Originally Posted by BEagle

So pass the information on then!

BEags -with all due respect. When I am busy, the last thing I would have time for is passing traffic info on to (presumably) all the adjacent radar units, on all the (newly transponding) returns that I might be giving a service to just in case they might want to know about it. Conversely, the second last thing I have time for is continually answering a ringing landline from someone asking for traffic info on traffic that I may, or may not, be working. To suggest otherwise shows that you really need a visit (and beer) to the nearest friendly Scottish Centre methinks.

Originally Posted by BEagle

But spurious or ambiguous TCAS TAs generated against Mode A help no-one - hence I still believe that no-one flying an aeroplane of < 5700 kg under VFR in the 'open FIR' should be compelled to carry a transponder, but if they do, it must have height encoding.

Again the question is posed. How does anyone know that that Mode C, or Mode S height readout is actually verified ? Bear in mind that TCAS can only provide separation based on that vertical info (and not on any azimuth info), what happens if that height readout is wrong ? There have already been intersting TCAS incidents with ac climbing (into) conflicting traffic, because the Mode C was wrong and indicated (wrongly) that the traffic was below when in fact it was above !!

A large increase in the number of transponders will surely lead to a proportionate increase in the number of incorrect height readouts ?

Now, what if EVERYONE who had to have a Mode S installed called up their nearest ATC unit to get it validated EVERY time they went flying - how long before CAA would be issuing safety notices advising people not to do that as it was overloading controllers ....... my guess .... not long. Rather ironic don't you think ?

What also happens if Pilot A inadvertantly has the wrong pressure setting on his altimeter ? Am I right in thinking that TCAS assumes all height readouts are based on 1013mb ? What happens below the transition altitude ?

Although I am still reading through your fine table, I still also disagree strongly about making a transponder compulsory for VFR in Class D - Our club operates quite happily in Class D airspace, using standard entry/exit lanes and procedures, which keep us separated from the IFR approaches and climbouts. A transponder is not mandatory at the moment and (more importantly) experience has shown that it isn't a problem. If it ain't broke don't fix it.

Now, sure, I am pi$$ed off at the prospect of having to shelve out (yet) another wad because of some potential CAA ruling ... I am still reeling from the CAA move on Engine TBO (March 2006). In one bureaucratic pen-stroke my 700/1500hr engine is now declared unfit for flying club rental, because it is over 12 years old - cost to resolve this .. ? £20k !

My anger on Mode S (and the false premise being used to push it) would be abated somewhat if it was being paid for by those who want/demand/benefit financially from it. I also note that in the CAA RIA, they make a meal out of all the costs to GA/Business Aviation.

For all their accountants credentials it is surprising that they fail to point out the quantifiable commercial gains for airlines of making everyone else install Mode S. That is a figure I would like to see. It shouldn't be too difficult for the 'experts' to come up with one. Then perhaps the equation would be less one-sided and more transparent.

I would also like to know who most PPruners think should pay for Mode S?

GA ? Airlines ? Or hypothecated from Govts rip-off tax on Avgas ? Or the CAA/NATS ?

[jabberwok]

What also happens if Pilot A inadvertantly has the wrong pressure setting on his altimeter ? Am I right in thinking that TCAS assumes all height readouts are based on 1013mb ? What happens below the transition altitude ?

It's irrelevant. All transmitted heights are SPS regardless of actual altimeter setting. TCAS is therefore correctly determining the difference between relative altitudes even though these values are otherwise meaningless below TA.

[Aunt Rimmer]

Originally Posted by jabberwok

It's irrelevant. All transmitted heights are SPS regardless of actual altimeter setting. TCAS is therefore correctly determining the difference between relative altitudes even though these values are otherwise meaningless below TA.

In the cold light of morning, yes I can see clearly now

Blame it on a late night beer - and brain stuck in a wee loop.

Of course, what I was confusing it with is when someone sets the wrong pressure setting and my radar display then shows up for example FL064 instead of FL070 - the error is in the input, but the height readout is still correct (based on 1013mb) .....

..... ASSUMING THE MODE C IS WORKING PROPERLY ...... (which is still an unanswered point)

[NorthSouth]

Originally Posted by BEagle

such airspace may also be used by pilots wishing to fly in IMC. Without any transponder they would have to rely on the increasingly rare availability of primary radar for traffic separation

Why rare? There's no decline in the number of primary radars, quite the opposite - Doncaster and Inverness about to get their own, to name only two. And one of the very few examples of an SSR-only radar station in the UK recently had its primary reinstated. MoD has always opposed SSR-only and I can't see that changing.
NS

[jabberwok]

Of course, what I was confusing it with is when someone sets the wrong pressure setting and my radar display then shows up for example FL064 instead of FL070 - the error is in the input, but the height readout is still correct (based on 1013mb) .....

Yes - that the difference. We have to dial in a TA and QNH on the radar to make the altitude show a correct value. For pure TCAS work the datum is irrelevant.

[BEagle]

One concept suggested in the past was for a particular general Mode C squawk to indicate that a verified Mode C check had been carried out. But, of course, that would be too easy to abuse.

However, if the verifying unit issued a 'verification number' which the pilot then acknowledged, at least it would deter such abuse. E.g. the last 2 letters of the ICAO code plus the Julian date, then the next number in sequence plus the last 2 codes of the registration? So, for example, Brize Radar issuing a Mode C check to the 7th aircraft of the day, G-ABCD, on October 18th would issue 'verification VN291007CD'?

More work for ATC, perhaps - but probably worth it to have verified Mode C squawks generally available?

[Jumbo Driver]

Originally Posted by BEagle

However, if the verifying unit issued a 'verification number' which the pilot then acknowledged, at least it would deter such abuse. E.g. the last 2 letters of the ICAO code plus the Julian date, then the next number in sequence plus the last 2 codes of the registration? So, for example, Brize Radar issuing a Mode C check to the 7th aircraft of the day, G-ABCD, on October 18th would issue 'verification VN291007CD'?

Takes me back to the Air Defence Numbers we used to have to overfly Burma ...


JD

[Aunt Rimmer]

Originally Posted by BEagle

However, if the verifying unit issued a 'verification number' which the pilot then acknowledged, at least it would deter such abuse. E.g. the last 2 letters of the ICAO code plus the Julian date, then the next number in sequence plus the last 2 codes of the registration? So, for example, Brize Radar issuing a Mode C check to the 7th aircraft of the day, G-ABCD, on October 18th would issue 'verification VN291007CD'?
More work for ATC, perhaps - but probably worth it to have verified Mode C squawks generally available?

You are taking the pi$$ now aren't you ? Please tell me that you are ? If not, common-sense and reason have finally been chucked out the window.

I've got a better idea. Why not mandate that every aircraft must have at least 2 seats and that one of them must be occupied by a valid ATCO, with his own Personal Radar .. oh dear then you'd probably need an extra seat for the CAA man to verifiy the verifier .... "just in case". Flourescent jackets would of course be compulsory ....

Better still .... gie it a rest - we are generally overcontrolled as VFR pilots and if you are being serious .... .... this rather smacks of the 'fighter controller' mindset, that requires that 'everything' is a threat until it has been identified.

It reminds me of the battle that was fought last year against the National Park in Loch lomond who were trying to ban seaplanes, for no other reason than the fact that what they don't understand they condemn.

So, the point was being made by National Park numpties (mostly Labour cooncillors BTW) (must be something about the nanny state mentality) about how dangerous it was having seaplanes landing near boats .. "they might collide" .. was the siren banshee call ... "how are you going to avoid boats"? etc..etc..

It was then pointed out to aforesaid numpties that the main A82 road , with some 35000 cars a day, travelling at speeds in excess of 60mph each way (120mph closing) manage to miss each other by only 6 or 7 feet ...... My goodness how do they do that ??!!!

.... by LOOKING OUT THE ING WINDOW.

Look - we don't need the aviation community adding to or going along with regulation for regulations sake ..... it's a nanny state and you either fight it or you get sucked in as a conspirator by giving these nanny state views legitimacy ... if you don't believe me have a look at the next daft proposal ...
http://news.scotsman.com/politics.cfm?id=1221422006

[BEagle]

Thank you for your valuable and reasoned contribution to the debate.....

[Aunt Rimmer]

Originally Posted by BEagle

Thank you for your valuable and reasoned contribution to the debate.....

Always a pleasure

So you really were being serious then ?

I didn't think I would need to explain why that proposal (Mode C Verification Number Allocation) is ludicrous, because I thought you were joking, and that it was self-evident. Don't be so offended if I choose to disagree with you, and if my tone may seem slightly aggressive . I AM angry at the Mode S proposals and I will make my views known, hopefully strongly and frankly.

(First some ground rules)
I am very much on the side of GA. I fly whenever I can. I regard myself as an aviation professional who is lucky enough to indulge a passion for flying. I believe these rights have been whittled away under constant and sustained attack from faceless bureaucrats and accountants for the last 10 years.
I am against over regulation (particularly for regulations sake or because it 'fits' somebodies big plan from on high)
I am a current ATCO and do my best to bend over backwards (not forwards tho) to help out all pilots.
I work Area sectors, 200x200 miles on a 15inch monitor - this encompasses huge areas in Scotland where there is no LARS service provider anyway - .

My prime task (as I am told by my employer) is toward Civil Air Transport. I personally didn't agree with privatising ATC because my feeling was then that everyone was equal but that would change ..... - well it's here now, so we have to live with it. The truth is if EVERYBODY called up for (or demanded?) a service the system would not cope because there really are not enough controllers to cope with that demand, even at Scottish ACC.

Now with respect to GA - maybe the situation is different in Merry Old England? Maybe you have plenty of free LARS units to call upon? I think we have two (Leuchars and Lossie) in the whole of Scotland, and even then only Mon-Fri and not in the busiest areas. ScACC provides it when we can - ie. if the controller can do it AND vector stuff in the airways, ADRs and UARs, but radar (and frequency) cover is not tremendous at low level, especially over the mountains. Below 6-7000 feet you will struggle to get a radar return, and below 4000 R/T will be suspect.

GA generally gets on with it without bothering or demanding much of the current system - and it works quite happily.

From an ATC point of view I (and most of the ATCOs I know who fly - which sadly is an ever-diminishing number) think it is much better if VFR ops are allowed or left to get on with it - sure, call up when you really need something, but if the CAA start to mandate the likes of Mode S, and then some authority insisted on allocating an idea like BEagle's "Mode C Verification Code" , very quickly you WILL swamp the system. The system (being naturally sympathetic to GA ) will then probably justify itself and start trying to look harder at ways of restricting you to prevent the swamping.

Maybe there are different issues in the important old southeast round the London TMA, well I still don't think it's a valid reason for the Deskbound Ones to impose unnecessary and expensive solutions on the rest of the country.

[Sedbergh]

Well guys

If you didn't respond to the CAA RIA

IT'S TOO LATE NOW!!!

If you get stuck with having to shell out loads of money for no discernable return to your aviation activities then ..............

[NorthSouth]

Originally Posted by Sedbergh

Well guys
If you didn't respond to the CAA RIA
IT'S TOO LATE NOW!!!

Not quite - you've got till 1700 today. You can respond online or e-mail your response to DAP.
NS

[Pitts2112]

Silly Radar Question

OK, this is probably going to be one of those questions to which the answer is so obvious that people stopped discussing it years ago but it seems that one of the issues that plagues the current ATC system is being unable to tell at what altitude an unidentified aircraft is flying, thereby not knowing if he's in, under, or over a particular piece of airspace. Hence Mode C with altitude encoding.

Here's my question. If airborne radar exists which can track fast moving targets from a fast moving platform, and sort out everything about everyones' positions and vectors to within a gnat's whisker, why can't ATC radar do the same? In other words, why does ATC radar need the aircraft to tell it what altitude it's at? I would have thought radar could be much more accurate than steam-driven altimeters anyway.

Am I missing something here?

[VP959]

If airborne radar exists which can track fast moving targets from a fast moving platform, and sort out everything about everyones' positions and vectors to within a gnat's whisker, why can't ATC radar do the same? In other words, why does ATC radar need the aircraft to tell it what altitude it's at? I would have thought radar could be much more accurate than steam-driven altimeters anyway.

Mechanically scanned radar heads suffer from relatively poor bearing discrimination, plus can only normally check azimuth or elevation separately; normally two synchronised heads are required to acquire azimuth and elevation data together.

The total bearing accuracy is typically about 1 degree at best, maybe worse than this in elevation, due largely to beam width limits. A target at 5000ft and 30 miles from the radar head has an elevation angle of less than 2 degrees, so sufficiently accurate height data is simply impossible to derive from conventional radar at realistic operating ranges.

It is possible to use radar to get better 3D pictures of close-in airspace using military phased, steerable array technology, but still not to the altitude accuracy needed to control lots of CAT at say 30 to 50 miles range. At the moment the civil radar heads used by ATC are a little bit more antiquated than the best military kit.

[robin]

Just seen this in the paper on the 'launch' of future usage of UAVs.

http://www.guardian.co.uk/uk_news/st...860787,00.html

I'm I right in thinking this was deliberatley held back until the day after the Mode S consultation closed, and if so, what does that say about the CAA's attitiude to the consultation?

[bogcleaner]

http://aviation-safety.net/database/...?id=20060828-1

Would suggest a good case for Mode S for anything airborne

[DaveW]

Originally Posted by bogcleaner

Would suggest a good case for Mode S for anything airborne

I'll look forward to wildlife being fitted with Mode S sometime soon, then.

This makes no such case, and neither would any other single data point.

Whilst we are speaking of this case possibly being used as spurious Mode S justification , though, I'd be interested to know:

1. If the Hawker 800 was fitted with Mode S itself?
2. If it was fitted with ACAS?

[mm_flynn]

I haven't looked but if the Hawker has 10 or more seats (seems likely) it is required to have ACAS. Given the high level of Mode S usage and ACAS in the states it would be realy surprising to find NetJets operating anything without both features (along with the full TAWS system the needed as well!)

[zkdli]

check the thread on rumour and news!