The second method listed is effectively the same as the U/AIS system that ships use[0]. The "U" stands for "Universal", from which we can deduce that actually only about 60% of ships actually use it.<p>The technology already exists, it just needs to be mandated for aircraft.<p>[0] <a href="http://en.wikipedia.org/wiki/Automatic_Identification_System" rel="nofollow">http://en.wikipedia.org/wiki/Automatic_Identification_System</a>