PilotAware
British Forum => General Discussion => Topic started by: Vic on May 15, 2021, 03:57:08 pm
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UK Airprox Board report on an incident at Turweston in December last year.
https://www.airproxboard.org.uk/uploadedFiles/Content/Standard_content/Airprox_report_files/2020/Airprox%20Report%202020167.pdf
Turweston are lucky to be involved with the team at PilotAware and have worked with them to help
develop the Air Traffic Overview & Management (ATOM) system. This was the game changer on the
day as the AGO was able to observe the track of the military aircraft and it was obvious to them that it
would fly through or close to the airfield circuit. So they took the decision on safety grounds to make a
general broadcast to all traffic making them aware of the jet and its position/altitude and the fact that its
track may have put it into conflict, or at least surprise, the Turweston circuit traffic.
Obviously this will spark the debate (I'm thinking Flyer forum here ::) ) of whether the AGO should have done what he did in effectively pass traffic info but hey, he'll have had to live with the consequences if he hadn't and things had worked out differently!
The UKAB have made it pretty clear to me though, that, in the circumstances, he did the right thing..
The Board first looked at the actions of the AGO. In providing an AGS, they were not required to provide
Traffic Information, other than to pass on known position reports from other pilots. Nevertheless, the
PilotAware ATOM provided the AGO with information that the Phenom was approaching from the north,
and the AGO broadcast this information to the circuit traffic. The Board commended the AGO for their
actions; although some advisors to the Board cautioned against the reliance on, and usage of,
unlicenced equipment and the lack of training thereof. Certainly, a CAA advisor was concerned that an
enthusiastic, but unqualified, AGO could potentially pass inaccurate information that then distracted a
pilot and that the lines between a controller using a calibrated radar and an enthusiast using a web
based program could become blurred; leading to potential confusion for pilots as to the type of service
being provided. This view was echoed by an MAA advisor who noted that such web-based programmes
could potentially have a lag of up to 7 minutes, meaning that it was not possible to know how accurate
the information was at any given time. Nevertheless, on this occasion, the actions of the AGO had cued
the RV9 pilot to look for, and see, the Phenom and the majority of members thought that it was a positive
result
I see the RV had a Skyecho, but seemingly didn't 'see' the Phenom with that!
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I see the RV had a Skyecho, but seemingly didn't 'see' the Phenom with that!
Was the Phenom outputting ADS-B or Flarm as it it wasn’t then SE2 would not see it and this shouldn’t be a surprise.
I see the RC had a Skyecho, but seemingly the Phenom didn’t ‘see’ it but then does the Phenom have ADS-B in?
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I see the RV had a Skyecho, but seemingly didn't 'see' the Phenom with that!
Was the Phenom outputting ADS-B or Flarm as it it wasn’t then SE2 would not see it and this shouldn’t be a surprise.
I see the RC had a Skyecho, but seemingly the Phenom didn’t ‘see’ it but then does the Phenom have ADS-B in?
In the Recorded Section above Reported it is alleged that the Phenom was putting out Modes A, C & S. The RV9 was Mode A/C. Now, Sky Echo 2 had bearingless turned off in software a few revisions back, so it wouldn't have seen the Phenom. The Phenom was running TCAS II, so depending on the current SIL/SDA value output the by the SE2, the Phenom might have seen it, but without knowing what they trigger on, and if they ignore CAP1391, I can't say.
However, TCAS II should be able to interrogate a transponder?
My own very brief experience with the SE2 on the dash is that the range isn't great and is not uniform 360 degrees round. However, it should be good enough for close up stuff.
ATOM would have seen the Phenom via 3D mode-S, or MLAT, or whatever you want to call it.
As for the Flyer forums... shrugs... awaits homogeneous echo from the chamber tainted with self righteous indignation...
Now a PAW in the aircraft would have started audio warnings with "Traffic, six o'clock, level, 3km" and got keener as time passed.
The audio is so under rated for dealing with aircraft with a location...
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I have a couple of mates with their own aircraft and have SE2s and I have been checking on how a local ATOM station 'sees' these aircraft using James' new facility /GROUNDSTATIONS at AIRCREW. it does not seem that ATOM stations get them very well and it therefore makes me think I am unlikely to get good reception of them with my PAW Rosetta. Actually I have flown in convoy with one mate and never picked anything up, he only has Mode C and SE2. I even wonder whether it might make sense for ATOM stations to re-broadcast anything from SE2 so that we have more of a chance to 'see' something.
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I have a couple of mates with their own aircraft and have SE2s and I have been checking on how a local ATOM station 'sees' these aircraft using James' new facility /GROUNDSTATIONS at AIRCREW. it does not seem that ATOM stations get them very well and it therefore makes me think I am unlikely to get good reception of them with my PAW Rosetta. Actually I have flown in convoy with one mate and never picked anything up, he only has Mode C and SE2. I even wonder whether it might make sense for ATOM stations to re-broadcast anything from SE2 so that we have more of a chance to 'see' something.
If the ATOMs don't see them or dont get them well then there's little or nothing to rebroadcast - as the SE2 is 1090MHz it should work well directly to your PAW.
I've done some flights with an SE2 and it was significantly below a PAW with external aerials on the same flight, in the same aircraft, performance wise. I prefer to check with Vector (pilotaware.com/analysis/vector (http://pilotaware.com/analysis/vector)) as it gives a simpler to understand 360 pattern if radiation. However, no point getting into arguments, different strokes for different folks...
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Steveu
I must have not made myself clear. I think ATOM stations are likely to be picking up more than more than my Rosetta when it comes the SE2 transmissions and that some supplemental info from ATOM stations would be useful.
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Steveu
I must have not made myself clear. I think ATOM stations are likely to be picking up more than more than my Rosetta when it comes the SE2 transmissions and that some supplemental info from ATOM stations would be useful.
Have you considered that the problem might actually be the range of the SE2, and nothing to do with the ATOMs or PAW?
Why don't you put the ICAO code of the SE2s in question into Vector and see how well they perform?
Vector showed me that there was an obscuration problem with a SE2 I borrowed. I relocated it and the range and the all round conspicuity improved. However, it was still a long way behind a Rosetta with external aerials.
Maybe we should check the more basic things before we ask for the system to be re-jigged?
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SteveU,
Supposing the Guys with SE2 don't bother about your feelings - is there something ATOM stations can do to make this better for us.
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SteveU,
Supposing the Guys with SE2 don't bother about your feelings - is there something ATOM stations can do to make this better for us.
I think the answer is no as I have done some measurements - maybe you can do your own measurements to compare the two devices and provide an alternative view?
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SteveU,
Supposing the Guys with SE2 don't bother about your feelings - is there something ATOM stations can do to make this better for us.
We have thought about this ...
Even with the high gain antenna we use on ATOM, we are struggling to see SE2 in many installations
it seems there is a wide range of performance
But if we have no data, there is nothing to uplink :(
Thx
Lee
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SteveU,
Supposing the Guys with SE2 don't bother about your feelings - is there something ATOM stations can do to make this better for us.
When we first started out with PilotAware, we were guilty of not worrying too much about the gain and placement of antennas for the ‘1090 side’, as this side was dealing with (relatively) strong signals from high-power transponders. With the advent of CAP1391 however, evidence indicates that we all now need to revise our thinking in this respect and need to consider optimising our antennas and antenna placement to take account of the (comparatively) weaker signals from CAP1391 devices in the same way we always have for FLARM and P3i.
Regards
Peter
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Comparison of ADS-B (grown up) and CAP1391. Aircraft results are similar. 20W v minimum 70W.
Any other evidence?
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One thing to consider when comparing DF17 & DF18 reception is height of the aircraft. You will pick up many more DF17 signals from greater distance as many will be much higher than the DF18 signals. It would be interesting if you could place an upper limit on the graph to have a more alike comparison.
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One thing to consider when comparing DF17 & DF18 reception is height of the aircraft. You will pick up many more DF17 signals from greater distance as many will be much higher than the DF18 signals. It would be interesting if you could place an upper limit on the graph to have a more alike comparison.
Vector graphs are similar when comparing PAW and SE2 from the aircraft. And the power output of PAW is a fraction of CAP1391. The height profile can be seen when logged into the ground station, and of course most CAP1391 aircraft are lower, and there are fewer of them but my own experience of the SE2 is as per the evidence I've submitted. I don't think it's for me to spend time on someone else's argument, if they are inclined, fine, if not.... IIRC the ADS-B reception is actually artificially limited at 80km...
ADS-B is 70W, and with external aerials... that's most of the difference I think I see here.
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Peter,
Thanks for your comment. But here is my problem. I own a PA28-181 and you cannot put outside aerials on this hull without a lot of trouble/expense permission wise. I have spent what some of the guys on this forum would class a lot of money in making my Garmin transponder 'ADSB out' certified. I say all this so you have the context.
What I am trying to say is that as with FLARM the ATOM stations might possibly transmit to us standard Rosetta types (inside aerials) some info on SE2 equipped aircraft... if that info is available to the ATOM stn.
We cannot expect the SE2 guys to optimise their transmissions, we can only be grateful they have done something and purchased some EC.
Can PAW ATOM stns redeem the situation a little without me having to drill holes in my PA28 ?
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IIRC the ADS-B reception is actually artificially limited at 80km...
its clipped at 60km, otherwise our databases simply get filled
Also, I changed the altitude profile to only report everything below 5000ft, the highest we were seeing in your plots was CAP1391 at just over 5000ft
This made no difference to the overall picture
Thx
Lee
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Peter,
Thanks for your comment. But here is my problem. I own a PA28-181 and you cannot put outside aerials on this hull without a lot of trouble/expense permission wise. I have spent what some of the guys on this forum would class a lot of money in making my Garmin transponder 'ADSB out' certified. I say all this so you have the context.
What I am trying to say is that as with FLARM the ATOM stations might possibly transmit to us standard Rosetta types (inside aerials) some info on SE2 equipped aircraft... if that info is available to the ATOM stn.
We cannot expect the SE2 guys to optimise their transmissions, we can only be grateful they have done something and purchased some EC.
Can PAW ATOM stns redeem the situation a little without me having to drill holes in my PA28 ?
I’m sorry, but IMO we certainly should ‘expect the SE2 guys to optimise their transmissions’ - in the same vein as we (and FLARM) advise our users to optimise ours.
From what we read on other Forums (Fora?), however, the advocates of SE2 are already convinced that we are deliberately misreporting their transmission range and more importantly polar diagram coverage via PAW VECTOR, and that PAW ATOM stations are in some way ‘biased’ against CAP1391 devices.
According to the proponents of SE2, operating range ‘air-to-air’ is vastly superior to ‘air-to-ATOM’. With this and the apparent coverage range restriction of the devices (as reported by Ground Stations) in mind, it is debatable to what extent capture and rebroadcast would be effective.
Setting aside the conspiracy theories, the fact still remains that if the Ground Stations can’t see the devices, we can’t rebroadcast their positions - even if we want to.
Regards
Peter
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A thought that I have been pondering for a few weeks.
An aircraft had a SE2 and also transmitted mode S.
If a PAW detected the mode S as bearingless but does not detect the CAP1391 and therefore requested info from a ground station would either:
a. The MLAT position be broadcast,
b. The Cap1391 derived position be broadcast.
or
c. The request be ignored as the target has a Cap1391 device that the PAW should be able to receive.
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Peter,
You might hope SE2 users will optimise their transmissions but my experience is that they are just switching SE2 boxes on and expect they are working. I suspect a lot of SE2 boxes were bought because there was a nice discount for something which was offering EC.
I am not hopeful that we can influence the SE2 world of users to implement what marginal improvement might be possible.
You supply some interesting info from other forums which I do not follow.
The question Cottie poses seems relevant.
I would like to know the count of SE2 contacts my PAW sees per flight. If none of us is seeing much SE2 and obviously ATOM stations are not seeing much this looks to be a problem that should be addressed.
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Iain,
In reality it’s a bit complicated, but in essence the ground station won’t know whether or not you are actually receiving the CAP1391 device or how reliable the signal is, so if your PAW also detects a Mode-S signal and is in communication with one or more Ground Stations, it will still request position data for that Mode-S signal. If available, the MLAT’d Mode-S position will be uplinked to the requesting PAW from the most effective Ground Station - as determined by the Network GRID Control. This data is then integrated with any other data for that aircraft by the PAW software, which will send a report based on whichever is the ‘most reliable’ data for that particular aircraft to your traffic screen. Hope this helps clarify what is in essence a fairly complex operation.
Regards
Peter
Edit: obviously it’s even more complicated than I thought, viz Lee’s post below! Sorry
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Peter,
You might hope SE2 users will optimise their transmissions but my experience is that they are just switching SE2 boxes on and expect they are working.
Whilst that is inevitably true for many (simply ticking a box), from the level of interest, discussion and argument on some of the more general public forums, a fair number of new SE2 owners are starting to question whether their devices are performing to an acceptable level and if not, what they can do to improve things. It is after all in their own interests to optimise their own installations.
I suspect a lot of SE2 boxes were bought because there was a nice discount for something which was offering EC.
Influenced significantly by the fact that a very vociferous group on the Flyer Forum and elsewhere take every opportunity to stress that ADSB-Out is ‘the CAA’s preferred EC option’.
I am not hopeful that we can influence the SE2 world of users to implement what marginal improvement might be possible.
I’m not sure that is the case as much as you might think. There is plenty of interest from users of ALL TYPES of EC in maximising the benefits of their systems. It does, however, require a bit of tact and diplomacy to point out to someone who has bought a product that it might not be performing to the level they think it is, and to suggest how that lack of effective performance might be improved. Fortunately the more technically aware SE2 users also have a vested interest in persuading their fellow users along the right path, so let’s not give up hope yet.
You supply some interesting info from other forums which I do not follow.
The question Cottie poses seems relevant.
I would like to know the count of SE2 contacts my PAW sees per flight. If none of us is seeing much SE2 and obviously ATOM stations are not seeing much this looks to be a problem that should be addressed.
Although the ATOM-GRID Network can differentiate between ADSB from a transponder and from a CAP1391 device, it’s not possible to determine that at PAW device level at present. I’m not sure how easy it would be to add this facility and in any case, we have to be careful as we don’t want to antagonise the ‘anti-PAW’ Brigade - who already think we are deliberately working against their devices (which is of course complete rubbish - they don’t need any help in that from us!).
The best we can do is to continue to work together to diplomatically advise users of ANY EC System as to how they might improve their setup where we come across obvious deficiencies.
Best Regards
Peter
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A thought that I have been pondering for a few weeks.
An aircraft had a SE2 and also transmitted mode S.
If a PAW detected the mode S as bearingless but does not detect the CAP1391 and therefore requested info from a ground station would either:
a. The MLAT position be broadcast,
b. The Cap1391 derived position be broadcast.
or
c. The request be ignored as the target has a Cap1391 device that the PAW should be able to receive.
Hi Iain
not sure if this is a similar question to the one on the FF (maybe you also posted there ?)
the answer as I mentioned on FF is C from above
Which I am now starting to doubt is the right approach....
Thx
Lee
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We cannot expect the SE2 guys to optimise their transmissions, we can only be grateful they have done something and purchased some EC.
And what about those of us who have put up ground stations at our own expense?
If the SE2 guys don't want to maximise their EC, why do we have to carry the can? Everyone else is optimising.
Those of us erecting ground stations might be doing a lot more optimising... and have made the optimisation possible.
If the SE2 guys don't optimise, their transmissions may not be received even by ground stations.
In the end all you can do is fly with a PilotAware and a SE2 on the same flight and note the results, in your aircraft.
I have but I'm suggesting you gather your own evidence.
Your main problem is that the PA28 is an all metal aircraft and will act like a partial Faraday cage for any carry on you have.
This is the main problem with any carry on, and it will limit PAW signals in and out, and SE2 signals in and out. This is probably the issue you have with not seeing much ADS-B.
Whilst I realise that you cannot have external aerials, I am in an aircraft where I can and the results are very different.
Rebroadcasting ADS-B upwards from ground stations towards the metal under surfaces of any aircraft is less likely to work than air to air, so the SE2 posse may be right when they say the air to air is better, but that's the obscuration of their metal hull at work.
Bottom line - there is a reason why a metal (or metal lined) apron is given to people having X-rays to protect their tender parts. The same metal "protects" antennas from receiving transmissions.
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Lee, Peter, and SteveU thanks for your feedback and comments.
Peter and SteveU
Lets hope you are right about the SE2 guys optimising the placement of their kit. I may be being too hard on them generally. On an individual level I have tried to help an AA5 flyer friend with an SE2 but his Vector diagram is still pathetic. If anybody has an AA5 and can show the best position I will pass the info on to my AA5 friend. I did not argue his choice of EC as he only has a mode C transponder.
SteveU,
I have the Rosetta in the rear window P1 side of my Archer and am very impressed with all the Uplink MLAT data from Selsey etc. I even get reports on MLAT circuit traffic at Shoreham albeit intermittently. I see a fair amount of 'P' contacts, and ADS-B contacts though probably from transponders. If we could get Aircrew to differentiate between SE2 and transponder ADS-B I would be wiser without the difficulty of trawling through the data by hand
So the spam can is not too much of a problem interference wise.
Well done with the ground station.
Phil
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Hi Phil
I have the Rosetta in the rear window P1 side of my Archer and am very impressed with all the Uplink MLAT data from Selsey etc. I even get reports on MLAT circuit traffic at Shoreham albeit intermittently
You will be pleased to know Shoreham/EGKA went live this weekend !
Thx
Lee
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Great news.
Can you send me contact info for future reference please?
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Lets hope you are right about the SE2 guys optimising the placement of their kit. I may be being too hard on them generally. On an individual level I have tried to help an AA5 flyer friend with an SE2 but his Vector diagram is still pathetic. If anybody has an AA5 and can show the best position I will pass the info on to my AA5 friend. I did not argue his choice of EC as he only has a mode C transponder.
Why not post his vector diagram here with the ICAO code and the aircraft type blotted out? Suggestions can be made. Screen dump Vector, edit the picture and attach.
I got poor results on the centre of the dash with the Skyranger. Moved the SE2 to the side windscreen passenger side just in front of the door post. Much more uniform radiation on Vector.
You will be pleased to know Shoreham/EGKA went live this weekend !
Thx
Lee
This is a real result for all the HG/PG posse flying at Devil's Dyke - this station is less than 10km away for the take off....
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SteveU,
It may be better to PM you the reg, and I'll find the current position of the SE2 in the AA5. This will avoid me drifting this thread anymore from the original title, which was a very good account.
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Wilco.