Primarily for general aviation discussion, but other aviation topics are also welcome.
By thegasguy
#1855299
A rather odd experience yesterday flying back from Lee on Solent to our strip in North Kent.
I'd love to know if it's happened to anyone else as it makes me doubt my lovely new SE2 - or maybe someone else's PAW, as you will see.

Brief overview;
Flying home from Lee on Solent as a 3 ship of Jodels ; picked up my colleagues 'trace ' on Skydemon right from taxi-out through take off and climb out.
I'm last as usual,and a bit slower as usual, and off we go East up the Solent with the other two in sight but pulling away.
I'm getting multiple targets 'painted' on Skydemon via SE2, all of which I see and are accurate as to bearing and relative height. I also see some aircraft crisscrossing to the IoW that don't show on screen. So far so ordinary.

A bit later I'm near Goodwood and to my surprise I see my 'leadship' trace is between me and the coast, lower down, climbing slowly and converging. This is very unusual as I've flown with him virtually every week for years and this is out of character plus his Jodel goes like the clappers compared to mine (annoying me in the process).

I've got a very very experienced passenger and I ask him to have a look. He can't see him so I S turn and have a look - I can't see him.
To cut a long story short, I followed the trace ( which was consistent, steady etc) all the way to Mayfield VOR, sometimes below, sometimes above, and closed to 1/2 mile with 2 sets of eyes looking for an aircraft I see every week without fail - and it just was not there.

I called out ' he's crossing the railway line..3, 2, 1, Now,etc etc but no sign of him at the designated spot at all.
One anomaly was that I had to slow down to avoid getting too close to the 'phantom trace' - this would never happen.

Then, I called 'he's directly over Mayfield VOR -now' and I knew he wasn't,as I was looking at it sitting in a field just ahead under a clear sky.
Passenger a bit bored of the game "no- he isn't".
As I glance down to SD maybe 30 seconds later (yes I was keeping a good lookout of the window!) the trace was at Crowborough, then 1 min later Tunbridge Wells.

That's going some, even for ' Rocketman.

So that's it really; can one trust the position of targets on screen- or not?

Sort of linked to this subject; on arrival at the strip I made my downwind call watching a Spitfire arcing round a nearby large landmark on the North Downs and rolling out straight down final, more or less pointing at me.
I repeated the call with a jokey addition of ' avoiding Spitfire' to alert my friend who was inbound close by.
He cheerily told me later that he got a nice wing waggle, all was well.
However, I had to change course, change power, change height and nearly passengers pants while established in the circuit and it's the third time I've had a close encounter with a Spitfire in a year but I've never seen one ' on screen'.
Do they carry any transmitting devices?

I love them to bits and would have a ride if it didn't mean sacrificing a years fuel for Jilly Jodel, but I see more out of the window than the Luftwaffe did and I'd like some warning.
Context- I usually see the two seaters around as I cross the Weald, North to South and back, but I think it was a single seater holding off to the North of Headcorn air show yesterday. Great that air shows are back on and it was Class G, so, No harm-No foul.
We have no ATZ, but are on all the charts.
No encounters warranted a MOR, airprox report or anything else, just asking if I should be able to see them on SE2/SD.
User avatar
By PaulSS
#1855300
Why would you doubt someone else’s PAW when it is ADSB/possibly Flarm you are seeing on your SE2?

Not a stroppy question; just trying to get to the heart of your understanding of what should and should not theoretically be displayed.
#1855332
The OP mentioned this happened near Goodwood.
Isnt the uavionix Goodwood trial aiming to rebroadcast MLAT, from their own derivative data source?

Has this possibly begun operating?

Can anyone confirm the ICAO/REG of the aircraft in question (PM) ?
By thegasguy
#1855352
I'm not sure I'm totally understanding the 'alphabet soup' of acronyms- but I know what I have on board as well as the other ones kit.
Unless I'm going bonkers - the other aircraft wasn't where the display said it was.
Two fairly experienced guys looked for it at close range for about 20 minutes, flying under,over and right up to it without seeing it.
Could have happened, but I'm convinced it didn't.
Then it covered about 15 miles in double quick time.

It's a bit disappointing that we had 4 aircraft out together and I can see two but not the third; that one can't see anyone; the first can see me and the 'blind' one but not the third; and he can't see the first( although he should; same kit) or second, but can see me if he's close - sometimes, even though I can see him 20 miles away.
Not really good enough for a safety system and it puts a lot of doubt in the mind.

Just as an aside, my SE2/ SD saw gliders near Parham at about 5 miles and was extremely accurate. I've got the Flarm add-on of course or that wouldn't work.
If the message could be changed to 'glider, circling' it would be better. By the time it rattles off the usual stuff it's going the other way and has to start again - and again - and again.
I had my device stuck on the front canopy/windscreen by then 'pointing' at the 'phantom' in case that helped locate it more accurately.

I've had a look at the vector chart thing and while my range seems a bit poor the coverage seems more or less ok radially - if that is important in understanding this.
By PA28
#1855355
For what it's worth. My experience is based on 5hrs a day 6 days a week. ADSB out position is gospel, the Pilotaware position lags behind the actual position by up to about 200m then catches up the actual position then lags and so on. ADSB is a very powerful transmission that can be viewed through a PAW unit and Skydemon up to about 80 miles away. PAW only transmits approximately 20 miles depending on the aerial location in the aircraft. Sky Echo is good as an ADSB in solution but is really poor as an OUT solution. The range is really poor. You often pass the other aircraft before their registration and position comes up on the screen. There is no substitute for looking out the window and I seldom fly without my pilotaware.
Forfoxake liked this
#1855367
PA28:
That chimes with my experience, the vector chart shows a weak 'out', but i'm very happy with the 'in' - it's been genuinely useful providing aural warnings.
This weird experience is very much a one-off.

I'm on the lookout for an 'aux' lead with a switch that I can use to mute it on arrival at fly-ins etc. ( no audio box on my aircraft, just iPad plugged direct into Bose headset)
Apart from that I'm totally in favour of EC: what a shame it wasn't one system that everyone can see !

By the way -as per original post - do Spitfires carry anything outputting EC ? Someone must know.
We go N to S through the kent area that they traverse E to W at much the same height so it's something I think about.
Just a quick add up reveals this:
I see them about 4 times a day over my house, maybe more (sometimes with a nice barrel roll over Hadlow Tower area) so 8 'instances'.
4 or 5 of us, so 10 chances countng ' there and back'.
Tend to fly twice a week- not always South of course so that reduces it a lot to be fair, but, if the mood takes us South then it's up to 20 chances of meeting times 8 = 160 'possibility units' of Achtung Spitfire.
And that's just us.
Statisticians will be going nuts at my sums, but I'm sure you can see what I'm getting at even if the units are wrong.
A rough line drawn from Biggin Hill to the memorial outside Dover will have a Spitfire on it somewhere for most of the daylight hours on any day with cloud above about 1500'.
Ask anyone else in Sevenoaks, Tonbridge, along the railway line to Ashford and beyond.
All I'm asking is, should they show up on my CAA sponsored box? If not, I'll keep looking into the sun and never flying straight and level for more than 30 seconds.
Never do anyway.
I'm absolutely not knocking; I never thought I'd live in a time where I can have a ride in one and they are so ubiquitous that I genuinely don't always look up , just wait for the noise to abate to resume my conversation in the garden.
User avatar
By PaulSS
#1855369
....do Spitfires carry anything outputting EC ?


I know G-ILDA has PAW. She's quite often over the Isle Of Wight and regularly shows up on my ATOM station.

I think she also has Mode S, as you can see the MLAT position but that tends to jump around a bit.

No evidence of ADSB, as far as I can see.
User avatar
By Flying_john
FLYER Club Member  FLYER Club Member
#1855373
Just to throw a little more into the pot.

Once upon a time (!) the Funke transponders used to output ADSB in a form that was displayable on FR24 (sort of combination of ADSB and MLAT), but would not be displayed on SkyDemon using various airborne ADSB receivers (PAW, Stratux etc) .

Recently Funke have their act together and they do now transmit ADSB that shows up on PAW, Stratux etc.

So is it possible ( in OP scenario) that the transponder of the lead aircraft appears to send ADSB but their is something different in the format or content of the squitter that does not get processed by PAW/Stratux as a true Ext Squitter and is therefore not displayed on SD ?

Edited to add:
If you watch the whole flight on FR24 it also shows KR appearing to do a turnback loop and then catch up with the rest.