You can't really use RadarBox to judge separation distances, as the kit isn't calibrated as per a real radar and you are looking at Network data which is only updated every 30 seconds at best. If you watch carefully, you will see that not every network track actually moves every 30 seconds as this depends on shared data and processing by the AirNav server. Believe me, if there is a erosion of separation, it doesn't go unnoticed either by the controllers, the radar display software or the pilots! Remember that passenger aircraft are equipped with TCAS (Traffic Collision Avoidance System) which gives the pilots a display even better than RadarBox!
Take a look at this link
http://www.airproxboard.org.uk/ if you want to see how incidents are dealt with, then you will see just how much information everybody has available to ensure separation. See the Publications section on the site for actual reports.
Also, you should know that the vast majority of "close calls" happen outside controlled airspace between aircraft not under an air traffic service - and you won't see these on RadarBox!
