Why don't all of the airplane icons show up on virtual radar?

[beamin]

Most times the planes wont show up on the google map. If it says its tracking 23 planes maybe 5-6 will show up on the map. Also if its tracking 2-4 planes often there won't be any on the map, even when you click on them on the box on the right. Is this normal?

 

[cpetraglia]

It depends on how much data is being sent from the planes. Look closely at the planes that do show up and notice the similarities. The ones not showing are missing something. I think it's either the call sign or the route. I'll have to bring mine up again and check.

 

[kma371]

If I understand you correctly, the ones on the map are transmitting ADS-B which gives GPS positions. The others not showing up on th map are using a different protocol, Mode-S/A/C which does not give position reports.