Primarily for general aviation discussion, but other aviation topics are also welcome.
#1693368
Bring it on.

All powered aeroplanes, gliders, airships, hang-gliders and balloons and should transmit ADSB on 1090. The affordable low-power technology is here and will continue to improve. Research should continue into possibly better alternatives, and the money should be earmarked now to subsidise the re-equipment of some or all of the fleet should it be shown that frequency congestion will occur.

Drones bigger than toys should find another frequency and inter-operate on that, but should detect 1090 and automatically avoid a 1090 target within ‘x’ kilometres or feet.

Simples.
gaznav liked this
#1693375
cockney steve wrote:
So, a classic case of bureaucrats spending other peoples' money for them, to address a vanishingly-small problem. - A sledgehammer to crack a walnut...
Those that err on the side of caution already have an adequate warning -system

More regulation and red-tape , just to show they are "doing something" :twisted:


Fitting the latest Garmin traffic kit (other manufacturers are available) doesn't do a better job of seeing than a mark one eyeball. It would if we were using a similar system to the USA but then where is the funding for that.
So we have an under-powered ADS-B out (so it won't interfere with the big boys) which will be a made for the UK solution (a very small market).
Forgive me but it is better than nothing and I will be fitting it.
#1693426
Actually, electronic conspicuity does a much better job than the mk 1 eyeball, in the case where there is actually something to see/detect.
Ian Melville, Straight Level, gaznav and 1 others liked this
#1693486
Where is the evidence that one frequency will not suffice in the UK/Europe?


AOPA Germany reported the following as recently as 4th April 2019.

A Google translation is as follows for those not fluent in German.

"For aircraft over 5.7 t MTOW or faster than 250 kts, EU Regulation No. 1207 of 2011 has an obligation to equip with ADS-B based on Mode S technology. The deadline for retrofitting ends on 7 June 2020.

An attempt to include all lighter aircraft in this ADS-B equipment commitment retroactively failed in 2017 when EASA found in the final report of Working Group RMT.0679 that an ADS-B Introduction to General Aviation would cause a congestion problem on the Mode S frequencies (1090MHz) and also not generate a positive business case. …………. the resulting analysis concluded that significant problems were associated with lack of sustainability of spectrum (with a special focus on 1030/1090MHz) and lack of cost efficiency associated with the overall surveillance system.”

Also at the EASA Electronic Conspicuity Forum in Cologne in February 2019, the high probability of 1090MHz spectrum congestion was convincingly demonstrated using empirical data gathered over a significant amount of time. The contributors were; DFS Air Traffic Service Provider, German Bundeswehr, Aircraft Owners and Pilots Association Deutschland (AOPA), Deutscher Aero Club (DAeC) - German Aero Club, Deutscher Segelflugverband (DSV), German Gliding Association, Deutscher Gleitschirm- und Drachenflugverband (DHV), German Hang gliding and Paragliding Association Deutscher Hubschrauberverband (DHV) - German Helicopter Association, Deutscher Ultraleichtflugverband (DULV) - German Ultralight Association and Vereinigung Cockpit (VC) - Commercial Airline Pilots Association.

Following this presentation, the EASA Forum organisers reconfirmed that work should be done on a future-proofed system rather than stretching 1090MHz in its current form for universal use by GA.
T67M liked this
#1693497
Nick wrote:
ls8pilot wrote:
T67M wrote:Agree completely

That said many ATC folk are much more sympathetic - the guys at Lyneham were great when that zone was active and Gloucester are always helpful. As always better understanding on both sides is needed, and at least with ADSB in future you can hopefully be seen.....


Heavily snipped.


Indeed the scissors may have slipped they were so heavy. I only said the first two words of that quote!
#1693526
Keith Vinning wrote:
Where is the evidence that one frequency will not suffice in the UK/Europe?


AOPA Germany reported the following as recently as 4th April 2019.

A Google translation is as follows for those not fluent in German.

"For aircraft over 5.7 t MTOW or faster than 250 kts, EU Regulation No. 1207 of 2011 has an obligation to equip with ADS-B based on Mode S technology. The deadline for retrofitting ends on 7 June 2020.

An attempt to include all lighter aircraft in this ADS-B equipment commitment retroactively failed in 2017 when EASA found in the final report of Working Group RMT.0679 that an ADS-B Introduction to General Aviation would cause a congestion problem on the Mode S frequencies (1090MHz) and also not generate a positive business case. …………. the resulting analysis concluded that significant problems were associated with lack of sustainability of spectrum (with a special focus on 1030/1090MHz) and lack of cost efficiency associated with the overall surveillance system.”

Also at the EASA Electronic Conspicuity Forum in Cologne in February 2019, the high probability of 1090MHz spectrum congestion was convincingly demonstrated using empirical data gathered over a significant amount of time. The contributors were; DFS Air Traffic Service Provider, German Bundeswehr, Aircraft Owners and Pilots Association Deutschland (AOPA), Deutscher Aero Club (DAeC) - German Aero Club, Deutscher Segelflugverband (DSV), German Gliding Association, Deutscher Gleitschirm- und Drachenflugverband (DHV), German Hang gliding and Paragliding Association Deutscher Hubschrauberverband (DHV) - German Helicopter Association, Deutscher Ultraleichtflugverband (DULV) - German Ultralight Association and Vereinigung Cockpit (VC) - Commercial Airline Pilots Association.

Following this presentation, the EASA Forum organisers reconfirmed that work should be done on a future-proofed system rather than stretching 1090MHz in its current form for universal use by GA.


Do those reports mention anything about power? The problem described is not considered a problem from the studies done in the UK if the power is kept down - which is the basis of CAP1391. However, I would agree with the studies you mention if we are talking Mode S transponders with outputs between 70W and 500W - especially for Class 1 above 250W or more. But for devices that are 20W or even less then 1090 congestion becomes far less of an issue as the QinetiQ studies have concluded and the subsequent release of CAP1391 has shown.
#1693713
@Keith Vinning

Hi Keith

At the link that Chris refers at Appendix D Page 5 it states:

QinetiQ has undertaken work for NATS [2], via the National IFF/SSR Committee (NISC), which shows that the introduction of significant numbers of ADS-B Out equipped GA aircraft would have minimal effect on the ability of the ground surveillance system to detect existing transponder-equipped aircraft. This work was undertaken using the initial SSR/IFF Environmental Model (SIEM1) which is used by the NISC to determine the effects of new systems on the UK IFF/SSR Radio Frequency (RF) environment.


The footnote [2] in the text is referring to: “Low Power ADS-B Transceiver (LPAT) RF Environment Modelling Study - Phase 2”, QINETIQ/14/01558, QinetiQ, A Peaty, 10th June 2014.

Appendix D is also the complete QinetiQ report on the effect on TCAS which concluded:

It is noted that TCAS employs Interference Limiting strategies to ensure that the availability of the TCAS aircraft’s transponder to reply to an interrogation will not drop by more than 2%. As this has been considered an acceptable level of degradation for an airborne safety system, it is possible that the figures described above could be considered to demonstrate that introducing EC devices should not cause a drop in Probability of Detection of a TCAS equipment by 2%.


That was 2% for a 70W device. The results for a 20W device, like a CAP1391 SkyEcho device, was around 0.1% which is negligible and probably why the CAA went for 20W in the end. I really think we need to put the 1090MHz congestion discussion behind us now that these independent scientific studies have been brought to light and concentrate on other challenges now with these systems. It is time to bust that myth and move on :thumright:
#1693732
QinetiQ has undertaken work for NATS [2], via the National IFF/SSR Committee (NISC), which shows that the introduction of significant numbers of ADS-B Out equipped GA aircraft would have minimal effect on the ability of the ground surveillance system to detect existing transponder-equipped aircraft


While I do not doubt this is true what I am more interested in is how the 'significant number of ADS-B Out' equipment is going to affect the ground surveillance AND airbourne surveillance to detect other ADS-B Out aircraft......NOT transponders.

We're being told we should all have ADS-B Out and this is the way of the future. All the QinetiQ study shows is how it won't affect the current infrastructure. I want to know how it will affect the future infrastructure when we're all equipped with ADS-B, when ADS-B is the replacement system for transponders and when that system can't cope because the test only went as far as ADS-B v transponders instead of ADS-B v ADS-B............in EVERYTHING (balloons, gliders, drones, SSDR, hang-gliders, as well as the 'normal' stuff).

I really think we need to put the 1090MHz congestion discussion behind us now that these independent scientific studies have been brought to light


I don't because the question has not been answered. A question has but NOT the one that needs answering. Low powered or not, the suggestion that it does not affect transponders does NOT answer the question of how it will affect future ATC & EC systems when we're all ADS-B Out equipped.
T67M liked this
#1694001
@PaulSS

I refer you back to CAP1391 to answer THE question:

5.5 It is therefore necessary to provide the NISC with adequate assurance that the technical specification for EC devices would not cause:

a. interference that compromises the performance of air-to-air safety nets such as TCAS or,

b. interference that compromises the performance of the ground surveillance infrastructure.

5.6 Item (b) has been addressed through a 2014 study by QinetiQ which considered impacts on ground surveillance infrastructure.


My bold, question answered and it seems that 1090 congestion is nothing to worry about from CAP1391 (which I also agree with from my own SQEP viewpoint).

:thumright:
#1694087
Well that's great. Low-powered CAP1391 equipment doesn't cause any snags with TCAS or GROUND surveillance infrastructure. However, we need to look at more than just CAP1391:

(a)Not all ADS-B Out equipment is going to be CAP1391 low-power gear, so more congestion would be caused in the real world by higher powered kit being mixed in than the study concluded in its imaginary world of all low-power. There will be a mixture of low and high powered ADS-B Out equipment floating around the skies and the study doesn't address that.

(b)I'm very pleased ATC or TCAS won't be affected. However, maybe I should have highlighted my point about EC i.e. air-to-air equipment (NOT only TCAS) being compromised by having the ether swamped by 1090 wiggles. With high and low power kit all over the place, what evidence do we have that ADS-B will continue to function as both Out & In for aircraft.....not air traffic controllers?
gaznav, T67M liked this
#1694100
The problem for 1090 is the overuse of 1030 interrogations by TCAS and SSR and the continued use of Mode 3/A - they are the 1090 big spectrum killers. As the US decided they would continue with Mode 3/A (they even continue to sell brand new ones) they had to go with the 978 fix. Europe is different and Mode S is far more efficient with 1090 - the word ‘Select’ is the clue.
#1694307
gaznav wrote:The problem for 1090 is the overuse of 1030 interrogations by TCAS and SSR and the continued use of Mode 3/A - they are the 1090 big spectrum killers. As the US decided they would continue with Mode 3/A (they even continue to sell brand new ones) they had to go with the 978 fix. Europe is different and Mode S is far more efficient with 1090 - the word ‘Select’ is the clue.


<My bold>
Somewhat of a subjective term :wink:
Have you reference to a 'independent scientific study' to quantify that Gaz?
SL