Interesting. I would still argue that it isn't a "false alert" though. If we are told that such an aircraft is (however briefly) descending towards you very fast, it is appropriate to say something about it. It's not clear what you would have us do differently about it.

Tim,

GPS isn't all or nothing. The red dots in your virtual radar, assuming there are no red dots on the main map representation of your flight, mean that only altitude was lost and not the rest of the GPS information. It's not that unusual actually, though it does depend on what GPS receiver you're using. I am not an expert on GPS receivers by any means but the SkyEcho GPS receiver is certified, and altitude is the most fragile bit of the GPS data because of the geometry of the satellites, so it would not surprise me to learn that altitude drops out MUCH more often than the lateral position/track/speed data when signal isn't very good.

Thanks Tim,

SkyDemon isn't getting confused. Perhaps I haven't explained that very well in this thread; if so I apologise. If SkyDemon is giving you a warning, it's because some traffic has indicated it's on course to conflict with you. Period.

Maybe, but I don't think so. Also I was at least 5000ft below the other aircraft.

Presumably because that aircraft briefly indicated it was descending towards you.

Tim,

No thanks, I don't think there's any particularly useful information it could give us.

Tim,