Proposed amendment of the ANO: Mode S

[tmmorris]

I guess it was an 'interesting trip' from Sleap?

I should confess at this point that despite visiting the facilities before departing Sleap, I quickly became aware that I would need to land to answer the call of nature very soon. I should really have abandoned the plan to go to Sleap at all and simply diverted home - or to Staverton - but I pressed on VFR in order to get to a loo quicker. Yes, VFR scud-running at 1500ft with the Long Mynd at 1693ft wasn't clever, and in fact has simply strengthened my resolve, as bookworm says, to get above MSA first and worry about the radar service second.

Tim

[robin]

Originally Posted by Sedbergh

OK guys, enough of the nit picking. The consultation period ends very soon now. Please get your views (in whichever direction) to the CAA as soon as possible.
Personally I am against the proposal on the grounds of high initial and ongoing cost against nil benefit to most users of light flying machines.
However the CAA electronic response form is so slanted that almost any reply could be interpreted as "favourable". Therefore I recommend that an "against" opinion should be voiced in a letter, copied to your MP.

Spot on Sedburgh. There are only a few days left now, so if you haven't done so, get your response in.

Having seen a number of different responses already, I think the CAA will be taken aback by the vehemence of some of the views, although whether or not it will be enough for them to think again is another matter.

At any rate we have identified a lot of the inconsistencies and downright fiddling of the data in the RIA, sufficient to take it higher if necessary

So make sure you add your names and views to the consultation before 17.00hrs on the 29th August

[BEagle]

Fair call, tmm! Joking aside, the debilitating effect of 'needing to go' can be very significant.

At least if more units had SSR feeds, the risk of the big sky theory failing would be less. Your 'bad weather pull-up' is (or was) often something faced in the military. Climb at best performance to Safety Altitude, then adjust to the correct quadrantal and call for radar if still IMC.

A corollary to the CAA's partial RIA might perhaps be a call for greater availability of SSR readout in ATC units? Not much point in being made to fit a transponder of any Mode if there's no-one able to see your squawk under the conditions you describe!

[Jumbo Driver]

Urgent - Response to CAA required !

Can I add my plea to those who have not yet responded to the CAA Consultation Paper. I heard earlier today that they have only received a few hundred responses so far - we really need to make our case heard.

It needs to be in by 1700 on Tuesday 29 August 2006; there are only 6 days to go, with a Bank Holiday weekend in between.

The link again:

http://www.caa.co.uk/default.aspx?ca...90&pageid=6476

Do it now !!


JD

[BEagle]

After much thought, I now suggest that:

1. With effect from 1 Apr 08, increased surveillance and collison protection should be introduced. This must be reasonable, affordable and proportionate to the degree of protection sought.

2. With effect from 1 Apr 08, Mode A should no longer be permitted within UK airspace.

3. No new Mode C installations should be approved after 31 Mar 10.

4. Minimum transponder requirements after 31 Mar 08 should be as per the following table:

Sorry if it's a little large. Anyone who wishes to cut and paste this into a response to the CAA RIA, please feel free to do so.

[Jumbo Driver]

BEagle, I agree with all you say, except your item 3.

I see no reason why a VFR aircraft below 2000 Kg should not be permitted to install a transponder with Mode C, after 31 March 2010.

If I understand you correctly, you would require him to install Mode S (if he installed anything), even though he would not be required by your table to carry Mode S if he only intended to fly VFR in Classes D or G, or SVFR in Class A.



JD

[QDMQDMQDM]

BEagle, why do aircraft 2000-5700Kg go VFR Mode C in your scenario in class D airspace, but Mode S in E-G?

[BEagle]

JD - Basically because, by then, it should be just as cheap to install Mode S as the market for Mode C would probably be no longer viable.

QDMQDMQDM - buggah! Damn cut and paste. It should have read:

2000-5700 kg. Class E-G IFR: Mode S, VFR: Mode C optional, Mode A not permitted.

New table:

[QDMQDMQDM]

Looks like a good scenario to me. Presumably, you're sending it to the CAA?

The real crux about this preposterous proposal for Mode S on all flying machines all the time is that it is unenforceable and there is no point having an unenforceable law. It simply makes criminals out of law abiding citizens.

QDM

[IO540]

It would be enforceable allright; it would just stop a lot of people flying.

Most pilots are law obiding people and, as a minimum, won't fly if their insurance is void the moment they get airborne (because of not meeting the equipment carriage requirements for the airspace).

I think beagle's proposal is excellent.

[BEagle]

Thanks for your comments, chums.

It has indeed been sent to the CAA and to others.

You are welcome to use it as you wish.

[QDMQDMQDM]

Most pilots are law obiding people and, as a minimum, won't fly if their insurance is void the moment they get airborne (because of not meeting the equipment carriage requirements for the airspace).

IO540, you are completely wrong if you think I am not going to go for a late evening tootle around completely empty North Devon airspace just because my Mode S transponder is u/s. I am afraid the rest of the muddy welly wearing PFA brigade will be the same.

And even if it is working, I may forget to switch it on.

It is unenforceable.

[Single Spey]

BEagle

Interesting proposal. However:

1) Class D airspace is a known traffic environment so ATC should not require you to have any transponder. By mandating a Mode C transponder ATC will now have no way of positively identifying you on radar except by primary radar and I cannot see many ATCOS wishing to give ident turns. 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. So this will be next to useless for any separation purposes.

2) What is the benefit in any transponder equippage in unregulated airspace? So that the TCAS equipped aircraft can take collision avoidance? Faced with a number of conflictions in a limited area, all equipped with Mode C, the TCAS algorithm has difficulty forming the correct tracks and evaluating the correct TA/RA. TCAS was designed to operate on fairly widely separated tracks with relatively constant flight paths. Its capability in the GA environment has not been proven to be safe.

3) Continued use of Mode C will not meet the CAA requirement to clean up the RF spectrum. Ground interrogators may still receive garbled replies and Fruit. TCAS will only be able to detect the Mode C equipped aircraft with a Mode C All Call transmission which is still damaging to the RF environmment.



In summary, given that you will not permit new Mode C installations from 2010, your proposal is a transition plan to Mode S equippage with some exemptions, but still does not give a quantitative estimate of how it will improve safety.

And where is the evidence/consultation that resulted in 'improved technical interoperabilty for ALL aircraft' being the only option under consideration?

[IO540]

Class D airspace is a known traffic environment

With perfect navigation, and everybody on the radio to the controlling unit, it could be.

What is the benefit in any transponder equippage in unregulated airspace

Probably the biggest one is in case the pilot wonders out of unregulated airspace.

Continued use of Mode C will not meet the CAA requirement to clean up the RF spectrum.

It would eventually, as people chuck out the old stuff. A lot of Mode C units are already ancient and rotting happily in British winters, and most new ones will probably be fitted to IFR tourers who have just had to rip them out and put in Mode S So there is a nice supply of cheap Mode C units. Currently, IFR pilots are having to sell them for a few hundred quid on U.S. Ebay.

[robin]

Originally Posted by IO540

Class D airspace is a known traffic environment
With perfect navigation, and everybody on the radio to the controlling unit, it could be.
What is the benefit in any transponder equippage in unregulated airspace
Probably the biggest one is in case the pilot wonders out of unregulated airspace..

No - if a non-radio aircraft wanders into CAS, what is the benefit? Surely it will show up as a primary contact in any event. It certainly won't enable the ATCO to call up the miscreant, although it will allow them to send an automated fine and 'you've lost your licence' to the owner

Originally Posted by IO540

Continued use of Mode C will not meet the CAA requirement to clean up the RF spectrum.
It would eventually, as people chuck out the old stuff. A lot of Mode C units are already ancient and rotting happily in British winters, and most new ones will probably be fitted to IFR tourers who have just had to rip them out and put in Mode S So there is a nice supply of cheap Mode C units. Currently, IFR pilots are having to sell them for a few hundred quid on U.S. Ebay.

But as QDM says, when flying for an evening bimble miles from any area of CAS, why is it necessary even to carry Mode C

[DaveW]

Originally Posted by robin

But as QDM says, when flying for an evening bimble miles from any area of CAS, why is it necessary even to carry Mode C

BEagle's proposal doesn't say it is: "Class E-G: Mode C optional".

Not convinced why Mode A should be prohibited, though. Say it isn't recommended, sure, but there are lots of aircraft around with xpdrs but no ALT encoding. Is this worse than nothing at all?

[BEagle]

Class D airspace is a known traffic environment.

It should be, in a perfect world. And then there wouldn't be any need for TCAS, of course. But the primary aime of TCAS is to resolve conflicts caused when pilots and/or ATC foul up. As happens. 100% height-reporting traffic will at least ensure that only genuine RAs are generated.

What is the benefit in any transponder equippage in unregulated airspace?

Flight in IMC is permitted outside CAS in UK airspace. Hence whilst we still have reasonable areas of free airspace where the 'muddy welly' PFA chaps can indeed enjoy lawful, non-RT VFR pottering - and long may that continue - 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 - or risk reliance upon the statistics of the 'big sky' theory.

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.

So pass the information on then!

Ground interrogators may still receive garbled replies and Fruit. TCAS will only be able to detect the Mode C equipped aircraft with a Mode C All Call transmission which is still damaging to the RF environmment.

Reply Garble is only likely with aircraft in very close proximity (such as in a holding pattern) and FRUIT is far less likely in terminal areas rather than in en-route Class A-C airspace. Hence my proposal for proportionate technical requirements rather than heavy-handed universal Mode S. I also have little faith in the CAA's assessment of the so-called 'damaging' L-band environment. It is probably as much of a fable as the nonsense of FM-immunity has proved to be.


And where is the evidence/consultation that resulted in 'improved technical interoperabilty for ALL aircraft' being the only option under consideration.

Quite. Don't ask me, ask the DAP.

Increasing numbers of CAT operations are being flown from regional airports without direct access to Class A - or even Class D`airspace. Unless the Air Traffickers are to be granted vaste chunks of additional regulated airspace, I consider that we need to provide improved conspicuity under IFR by mandating height encoding transponders for all aircraft flying under IFR. Which can, of course, be in 100% VMC. 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.

[robin]

Originally Posted by BEagle

[I] 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.

Sorry, I'm not following this, but I've no knowledge of how this works

You are saying that we need to carry a height encoding transponder IF we decide to carry one, so that IFR pilots (who may be passing by) can resolve conflicts using TCAS.

We may chose not to fit a transponder at all, as microlights and gliders are exempt under your proposal, and our Cubs, Aeroncas and Jodels can opt not to carry one, neither will military FJ traffic. So the odds are that the IFR pilot who may not be receiving an ATC service will have no idea of any traffic except the minority that choose to squawk. If he chooses to change course to resolve any conflict, then how does he know he isn't about to turn into greater danger?

The same things would happen if a Chavair flight cuts the corner into Class G.

Is this not a problem?

[BEagle]

TCAS either gives 'Traffic Advisories'(TA) which highlight the presence of all other transponding aircraft within a certain height and range envelope - or 'Resolution Advisories'(RA) if a clear risk of collision exists. To generate a RA, TCAS must know the height of the other traffic using either the Mode C or Mode S information from the other traffic.

TAs would be generated against any Mode A aircraft within range. But those could be spurious if the traffic was actually well separated by altitude - or, perhaps worse, should really have been RAs but couldn't be because TCAS didn't know the height of the Mode A aircraft.

I consider such dangerously ambiguous TAs worse than useless - and a bigger distraction than no information at all.

If 'Chavair' enters Class G airspace under IFR, at least he would get TCAS protection against Mode C aircraft flying in IMC without any radar service - as is currently legal in the UK. But the chances of VFR traffic colliding with 'Chavair' in Class G is far less likely - and is not sufficiently great to merit universal Mode S for all aircraft.

One final point. TCAS azimuth resolution is relatively poor. So it is never used by pilots to 'change course to avoid conflict'.

[Single Spey]

TCAS azimuth resolution is relatively poor. So it is never used by pilots to 'change course to avoid conflict'.

BEagle, you forgot the smiley