Primarily for general aviation discussion, but other aviation topics are also welcome.
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User avatar
By ls8pilot
#1803373
Crash one wrote:How many of the multitudinous list that Gaznav mentioned can “see” how many of the others.


Most of the list are just ADSB receivers, so rely on a separate transmitter. The exceptions are:

PAW - which sees other PAW, Flarm (via ground relay) and transponders as well as ADSB
Any PowerFlarm - which sees other Flarm (direct) and transponders as well as ADSB
SE2 which sees any ADSB emitter (so SE2 or Mode-S/ES) and Flarm direct (in conjunction with SkyDemon)

I think that's more or less it for transmitting devices (apart from mode-S/ES transponders which transmit but do not receive), there are some "Flarm Like" devices in the paraglider world which I'm not too familiar with, and an OGN beacon which is more aimed at tracking competition gliders from the ground (not used in UK AFAIK).

On the Drone side, which we shouldn't forget, there are implementations using Flarm and using ADSB, not aware of any (yet) using P3i although PAW seems to have a product aimed at that market.
Last edited by ls8pilot on Fri Oct 16, 2020 12:56 pm, edited 1 time in total.
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User avatar
By mooney75
#1803376
gaznav wrote:There are some weird manufacturers that do have crazy high SDA requirements still, but they are now thankfully in the minority. Even CDTI (Cockpit Display of Traffic Information) displays in airliners now have SDA=1 requirements due to the internationally agreed Traffic Awareness Beacon System (TABS) standard that devices like TRiG’s certified TN72 GNSS/GPS gives you.

There is nothing "weird" about following regulations. I think you are mixing up requirements for the transmitter (ADS-B Out) and the receiver (ADS-B In). SDA (System Design Assurance) is a design certification parameter (but can also be lowered based on the GPS source). It basically says what the reliability of your equipment is. You cannot have an SDA > 0 (at least you are not supposed to) if your equipment is not certified. This is why the CAA is bending the rules if they allow SDA=1 for non-certified equipment.

The requirements for the receiver (ADS-B In) are established in DO-317C. It requires different levels of SDA (and a bunch of other parameters) for the received signal to be used for different purposes and in different phases of the flight. SDA=1 is insufficient in many cases. It's much more complex than that. And this, of course, makes total sense. What would be the purpose of having certification requirements if any portable device lying around the the aeroplane could disguise itself as certified.
By patowalker
#1803380
Keith Vinning wrote:Such transmitters cannot automatically be used in any other Member State.


I think it is well known that SE cannot be used for ADS-B Out in any other Member State, but it is perfectly acceptable for ADS-B In, as well as for Flarm under subscription.
User avatar
By xtophe
#1803383
mooney75 wrote: SDA=1 is insufficient in many cases. It's much more complex than that. And this, of course, makes total sense.


Well, do share with us.


What would be the purpose of having certification requirements if any portable device lying around the the aeroplane could disguise itself as certified.

What will the pilot and passengers of a mid to high level IFR SEP/SET airplane say after a Airprox or midair with one of the great unwashed only transmitting SIL=SDA=0?
At lest I died watching a piece of certified TAS ?

Certification is not a panacea. It has some adverse effect.
#1803384
mooney75 wrote: And this, of course, makes total sense.


It makes total sense for a receiver to pretend that conflicting traffic does not exist because the conflicting traffic's GPS source isn't certified?

Whether it's certified or not it's still there, and you're just as dead if you hit it.
By G-JWTP
#1803388
Rob P wrote:Am I correct that this inability to use ADS-B specific EC devices other than in the UK does not prevent me using my Mode-S transponder once it it linked to a certified GPS source?

CAA UK CAP 1391 specifies technical specifications for Electronic Conspicuity (EC) devices and it includes specific requirements for the transmitter: this is a Member State approval.

A transmitter approved as part of “a Member State approval” shall only be used in that Member State under the conditions of that “Member State approval”. Such transmitters cannot automatically be used in any other Member State.


Rob P


See xtophe response to my question here.

viewtopic.php?p=1802641#p1802641

G-JWTP
User avatar
By gaznav
#1803393
@mooney75

William

Let’s just consider that certification, and how ‘reasonable’ it is. Someone PM’d me some thoughts that I fully agree with, to put that idea in context:

ADS-B ‘squits’ its data including position roughly once per second. So, a ‘bad’ GPS/GNSS position ‘squit’ could be replaced by good ones after a second, but that still counts as a failure.

SIL=1 equates to one of those 1 second failures permitted in 1000 flying hours.
For SIL=2 it is 1 error in 100,000 hours.
For SIL=3 it is 1 error in 10,000,000 hours.

So the question is, how appropriate are those failure rate performance requirements for GA?

Think of your average GA pilot, where most never even reach 1000 hours of flying in their lifetime.

Even a Pilot that does 50 hours a year takes 20 years to reach 1000 hours, and the SIL=1 benchmark says he’d be permitted one bad GPS position transmission lasting 1 second in the whole of that 20 years.

Can you see how CRAZY that is?!!! Think of the cost consequence imposed by that requirement for what benefit?

That is why, 4 years back when certified GPS cost £2k, the LAA, BMAA, A4A, etc... pushed the CAA so hard on accepting SIL=0. Now of course a proper installed SIL=1 GPS has come down to around £500.

And EASA CS/STAN accepts SIL=0 ADS-B Out now too even in CofA aircraft on a ‘no harm, no credit’ basis. So really the gulf between the reception of SIL=0 vs up to SIL=3 from some manufacturers needs to be challenged. The Australian CASA have come up with a good solution for SkyEcho to get things moving, hopefully the CAA will follow soon too. What we really need is for uncertified SIL=0 to be displayed on ALL devices/avionics fits - maybe a different colour or symbol - for the benefit of all, rather than hiding it from display like a naughty child.

Finally, for @Keith Vinning was the QinetiQ (2014) Low Power ADS-B. Transceiver (LPAT) RF Environment Modelling. Study - Phase 2. QINETIQ/14/01558. Not independent enough to put the frequency congestion argument to bed. QinetiQ are a world leading scientific research business that are totally independent of the CAA and NATS - why do you insist on keep calling this one out about frequency congestion when it has been scientifically modelled to not be an issue?
Last edited by gaznav on Fri Oct 16, 2020 6:31 pm, edited 1 time in total.
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#1803451
TheFarmer wrote:Why would I want a refund?

Pay no heed, he goes from repeating
neilmurg wrote:Life isn't complex, make a decision
EC? yes /no
Understand your environment, if you're in noplanesestan, EC doesnt help
Diffent options have different advantages
PICK ONE!
or whine about it and do nothing

to
neilmurg wrote:Just sayin. data will set you free. @TheFarmer , they have a great refund scheme

Not something to consider the refund button over. As you said it's the self cotradictory messages that set to confuse. Now if only your SkyEcho could warm the engine of a morning. :wink:
#1803459
gaznav wrote:[QinetiQ are a world leading scientific research business that are totally independent of the CAA and NATS - why do you insist on keep calling this one out about frequency congestion when it has been scientifically modelled to not be an issue?


Gaz,

Who asked for and who paid for the QinetiQ report?

Serious question, I don't know.

SL
User avatar
By ls8pilot
#1803499
defcribed wrote:
mooney75 wrote: And this, of course, makes total sense.


It makes total sense for a receiver to pretend that conflicting traffic does not exist because the conflicting traffic's GPS source isn't certified?

Whether it's certified or not it's still there, and you're just as dead if you hit it.


Some interesting comments in Airprox 2020040
https://www.airproxboard.org.uk/uploadedFiles/Content/Standard_content/Airprox_report_files/2020/Airprox%20Report%202020040.pdf

Members asked why Brize ATC did not use FLARM equipment to increase the controller’s situational awareness when some other military Air Traffic units do use it. The Military ATC advisor said that individual units are able use their discretion regarding the installation and use of FLARM because the data is not assured. On further discussion, it was stated by the ATC advisor that it is the FLARM height information that cannot be assured because legislature states that ATC cannot use geometric height information, it must be derived from the barometric pressure. The ATC advisor went on to say that the CAA is looking at cooperative EWS, ADS-B out, to be mandated for all aircraft from 2024 onwards. Board members said they were concerned about the slow progression of the EWS integration. The BGA member offered that some gliders do use barometric pressure with FLARM. Members opined that it could be helpful if the MAA had a universal approach to the use of FLARM in military ATC.

BTW - as far as I'm aware nearly all Flarm units do provide barometric information, based on a calibrated pressure sensor - it's needed for the IGC logfile. So basically Brize ATC elected not to use a system which they were allowed to use (by Military ATC regs), despite the fact that most civilian GPS systems are more accurate than the average SSR, just because the geomtric altitude could be different from the barometric altitude - by how much for goodness sake ! This reliance on "certified" systems dates back to times when there was a significant difference in the accuracy and reliability between certified and non-certified; if my car or phone GPS can navigate me to the right turn off a roundabout then surely it is better than a primary return or relying on Mk1 eyeball ?

....... Good performance by the Voyager crew in spotting the glider and taking action, those RAF eyesight tests must work after all!
User avatar
By Dave W
#1803502
ls8pilot wrote:The ATC advisor went on to say that the CAA is looking at cooperative EWS, ADS-B out, to be mandated for all aircraft from 2024 onwards.

If this is correct, such a discussion REALLY needs to be held openly, as a full and collegiate consultation, with all those involved and affected.

It requires an objective and impartial cost:benefit analysis, and must consider opportunity costs such as the potential impact on other risks to life for aviators.

That throwaway line is quite disturbing to me, and I hope it is a misrepresentation of what is actually going on behind the scenes.

That would be true even if 2024 wasn't no time at all away.
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User avatar
By ls8pilot
#1803506
Dave W wrote:
ls8pilot wrote:The ATC advisor went on to say that the CAA is looking at cooperative EWS, ADS-B out, to be mandated for all aircraft from 2024 onwards.

If this is correct, such a discussion REALLY needs to be held openly, as a full and collegiate consultation, with all those involved and affected.

It requires an objective and impartial cost:benefit analysis, and must consider opportunity costs such as the potential impact on other risks to life for aviators.

That throwaway line is quite disturbing to me, and I hope it is a misrepresentation of what is actually going on behind the scenes.

That would be true even if 2024 wasn't no time at all away.


Yes, I spotted that, but I think it's not a statement of policy - after all the strategy document indicates they are "looking at it", and this is just a rep on the Airprox board, although I'd not seen the date 2024 before........

My concern is this attitude of "I have access to traffic information (and presumably that could be Flarm, ADSB or P3i) but I'm not going to look at it because it's not officially certifed". Bit like "I ran over that cyclist but it's not my fault because he did not have BSI certified relectors on his pedals"
Last edited by ls8pilot on Fri Oct 16, 2020 10:52 pm, edited 1 time in total.
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