Lost planes

[Camerart]

Hi, My first post.

I have an RTL2838 dongle and running Dump1090.  I'v just made and testing a stripline antenna, which if on a 12ft pole sees planes about 180miles away.

I have an airport near me, and watched a small plane set off from the airport, and go north.  I was expecting a flight coming in from Spain, but it landed without showing on the map.  Does anone know why some planes show and others don't?

Camerart.

[Anmer]

Welcome.

Not all aircraft transmit Mode-S messages and of those that do, not all include positional data.

There's a Guide here that may help:

What's Radarspotting?