Courtesy of Flightradar24
What is Flight Radar?Flightradar24 shows live airplane traffic from different parts around the world. The technique to receive flight information from aircraft is called ADS-B
That means the Flightradar24 can only show information about aircraft equipped with an ADS-B transponder. Today about 60% (about 30% in USA and about 70% in Europe) of the passenger aircraft and only a small amount of military and private aircraft have an ADS-B transponder.