Ghost Plane

[tatonka]

Hi all,

i am planning to starting a feed, or at least experimenting with my DVB-T-SDR and ADS-B. So i set it up and used a tool to display the data on a map. And i detected a ghost plane. Flight number 5X11/UPS11, from Shanghai to Seoul. According to FR24, it flew right above me, located in Dortmund, Germany. Since Dortmund isn't on the shortest route between Shanghai and Seoul, i was suspicious. And it seems that my receiver doesn't detect it, although it should clearly be in range.
Its path on the map was clearly between Seoul and Shanghai, but it continued after Shanghai. It seems to be a clear path, although the blue line was dotted somewhere in between, especially when it flew above the Himalaya.
So i'd like to ask as a noob: How can that be? This plane isn't en route, and according to my receiver, it isn't there at all. But why does FR24 show it?

[airnrail]

FR24 assembles the info you see on the screen from a multitude of sources using computer algorithms. Occasionally the computers get it wrong. As an keen planespotter I have seen an American airliner that was actually flying a domestic route in the USA appear over Australia on FR24. Your example seems like a similar glitch. Most of the time though, what you see on FR24 lies between reasonably and very accurate and the glitches often correct themselves if you watch for long enough as the aircraft becomes visible to different feeders.