Strange Pilotaware tracking outside the UK

[buzz53]

Warning: geeky! I noticed something very odd at the weekend and wonder if anyone can explain it.

I was using www.glideandseek.com to monitor a friend’s flight from the south of the UK to Le Mans (France). GlideandSeek displays data from the Open Glider Network, to which PAW groundstations contribute data, making PAW users visible in addition to the FLARM users. My friend has a PAW Classsic without airborne internet connectivity.

He was tracked perfectly to about mid-channel and then disappeared. I believe there are very few PAW groundstations outside the UK so at first sight this might be expected but I understand that “normal” OGN stations without the PAW hardware added (the vast majority of those outside the UK) should also receive PAW as well as their native FLARM using their SDR dongles. A bit of research however showed that this OGN receiver functionality reportedly does not currently work. So the loss of tracking outside the UK still made some sense.

Now (finally!) here’s the interesting bit. I later checked the flight in the PAW database using the PAW Groundstation replay facility which I think is now quite well known. At first sight the same happened:  perfect tracking but only to mid-channel. However looking more carefully, there are individual track points logged every 2 minutes all the way to the destination. You have to look very carefully to spot the individual red dots.

I can’t figure out how this is happening. I don’t believe there is PAW groundstation coverage all along this route and if there was then surely there would be a normal complete track.  I also don’t believe there can be any air to air relaying going on and there is no internet connectivity. The only other option is that the OGN stations are in fact receiving PAW equipped aircaft and PAW are importing this data back into their own system which I didn't think they did. But in that case why would GlideAndSeek not display this same intermittent data, and why is it intermittent?

Hope this isn’t too garbled. Can anyone shed any light on what’s happening please?

Alan

[Admin]

There are many routes that data is now passed to/from our servers
As you quite rightly say, ground detection is one method, and that can be via ATOM stations or OGN receivers
Additionally, the airborne systems are also capable of using the cellular network (IGRID) to send and receive data when the system is paired with a phone
Finally SkyGrid allows passing of data via an intermediary to any of the downstream connections, ie ATOM and IGRID

So there are multiple paths that are in use simultaneously
Thx
Lee

[buzz53]

Thanks for the background info but note my friend had no Igrid connection so I'm none the wiser how this flight was tracked and why the datapoints are 2 minutes apart. The ID was 405BE9 departing Thursday 3rd July at 9:06Z.

As far as you know, do classic OGN sites outside the UK receive PAW?

Alan

[buzz53]

There doesn’t seem much knowledge of or interest in this topic but rather than leave it open I might as well briefly describe my conclusions after some investigation.

Classic OGN groundstations throughout Europe do indeed receive PAW transmissions, and forward them to the OGN servers. The data forwarded is labelled in a way that distinguishes it from the same data received and forwarded by PAW groundstations (which are almost exclusively in the UK).

The OGN servers supply data from both sources (and several others) to clients such as the various public tracking websites . Whether traffic from any particular source is displayed depends on the client and it so happens that my favourite GlideAndSeek tracker, which I was using when my friend “disappeared” mid-channel, does NOT show PAW aircraft received by OGN groundstations. I don’t know if this is intentional, and I have tried to contact the site’s owner, but with no response. Other trackers, such as SpotTheGliders and PureTracker DO show this traffic.

Regarding the odd 2 minute spots on the PAW groundstation tracker site, I’m sure Admin could have explained this straight away, but this must result from PAW taking data from the OGN servers for their own purposes and choosing to store only 2 minute samples.  Presumably this is just for statistical info on where PAW is actually used which is fair enough provided they comply with the OGN privacy policy on data use.

[steveu]

Thanks for the background info but note my friend had no Igrid connection so I'm none the wiser how this flight was tracked and why the datapoints are 2 minutes apart. The ID was 405BE9 departing Thursday 3rd July at 9:06Z.

As far as you know, do classic OGN sites outside the UK receive PAW?

Alan

1. The OGN is not controlled in the same way as the PAW/ATOM network. The hardware is diverse, the software is not automatically updated, and it was in some state of disarray after the FLARM encryption update last year. So there is no simple answer to "Do Classic OGN stations receive PAW?" Yes, if on the right software.

Even if your friend had no iGrid, his unit could still be part of the SkyGRID as seen by another PAW aircraft which could then use its iGrid to pass on your friend's location.

There doesn’t seem much knowledge of or interest in this topic but rather than leave it open I might as well briefly describe my conclusions after some investigation.

Classic OGN groundstations throughout Europe do indeed receive PAW transmissions, and forward them to the OGN servers. The data forwarded is labelled in a way that distinguishes it from the same data received and forwarded by PAW groundstations (which are almost exclusively in the UK).

See 1 above. Some tracker apps will tell you what version of software the "Classic OGN" station is on.

The OGN servers supply data from both sources (and several others) to clients such as the various public tracking websites.  Whether traffic from any particular source is displayed depends on the client

There you go... Unlike the PAW ATOM network, there are various levels of software and reporting on the OGN...

Regarding the odd 2 minute spots on the PAW ground station tracker site, I’m sure Admin could have explained this straight away, but this must result from PAW taking data from the OGN servers for their own purposes and choosing to store only 2 minute samples.  Presumably this is just for statistical info on where PAW is actually used which is fair enough provided they comply with the OGN privacy policy on data use.

As I understand it, the PAW system is run primarily for situational awareness and not tracking and there is a big difference in the philosophy of how they would work. Situational awareness data needs to be up to date and therefore during PAW talks, Keith V. has intimated that any data deemed not to be current enough to use would be discarded. That is the big difference, if you are tracking then a 45 second delay is not a big issue, whereas for situational awareness at higher speeds it is.

You could be right in that your friend data exists to help with unit performance analysis via either Vector or Playback/Groundstations software. I was also told that the reason for the PAW ATOM network was because there was too much latency in the OGN.

There is probably little interest in this because most users have PAW for situational awareness, not tracking. Whilst I occasionally track friends' aircraft, the best device for being tracked internationally is a mode S transponder, and if your friend wants to be tracked as opposed to made aware of other aircraft close by, this is the device to buy...