Paul,
Dave did try to attach the track log to a previous Forum post, but of course it's far too big. I did suggest using Dropbox, but he may have missed my suggestion, or not know how to do so.
If this is the case Dave, please get back in touch.
However, as far as I can see no one has answered the OPs' query as to why he was seeing us labelled up close to him and at a similar height, when we were transmitting ADSB-out from fifteen or more miles west of him and some 3000 ft above.
Ideas?
Without the track log(s), it is very difficult to answer this. In my years of testing, I have NEVER experienced a 'false alert' from a known position aircraft and have only ever heard of two instances (IIRC in the Project Eva Trials Report) where due to a technical issue, one of the aircraft was transmitting its position as the wrong side of the Greenwich Meridian.
The only way we will be able to resolve this issue properly is to look at Dave's PilotAware Track Log, however re-reading the thread yet again, the following points
are clear.
Firstly, Dave says of the first alert on his 'inbound' flight to Cromer
[My Edits....]
The aircraft on my inbound flight to Cromer was G-CCZD... [ - ]... it looked less than a mile at 12 o'clock (and stayed at 12 o'clock when I started the lookout weaving turns, so I'm guessing bearingless). So in fact, if he was a bearingless target, he could have been anywhere, as well as dead ahead, yes?
Regards,
Dave
The fact that the 'indicator' stayed at 12 o'clock on Dave's screen while he carried out his clearing turns indicates fairly positively that what he was seeing
was a bearingless contact indicator. If this had been a known position aircraft (P3i or ADSB), it would have moved round on the screen away from the 12 o'clock position as Dave turned his aircraft (the amount of movement would of course depend on how big / prolonged the clearing turns were, but nevertheless the contact
would have moved to some degree). It's also correct that a bearingless aircraft 'could' have been 'anywhere' [round 360 degrees, at the relevant altitude indicated on screen] as well as dead ahead.
A fault with G-CCZD (if for example the PowerFLARM temporarily stopped sending GPS data to the transponder), would cause G-CCZD to (temporarily) revert to Mode S, however it is unlikely that Dave would receive a bearingless target 'Alert' from G-CCZD's Trig TT21 at 15Km. Even if Dave was running Mode C/S Detect on 'Long Range', aircraft normally need to get much closer than this before bearingless target alerts start to appear on screen -
except in the case of CAT aircraft running high power transponders!Is it possible that what Dave saw was a bearingless alert from a CAT Mode S (e.g. Flybee) at long range and somehow confused this with the ADSB alert from G-CCZD, which would have been easily visible at this range, ....or was there a temporary fault on G-CCZD's transponder? Only a hypothesis, and
no disrespect or criticism whatsoever intended or implied to either Dave or G-CCZD, but without seeing the log(s), these are the only explanations I can think of that make any sense whatsoever.
As I say, the logs
will reveal all - if you can get them to Lee, Dave.
Regards
Peter