Planes are having their GPS hacked. Could new clocks keep them safe?BBCAs a Ryanair flight from London approached Vilnius, Lithuania, on 17 January, its descent was suddenly aborted. Just minutes from touching down, the aircraft's essential Global Positioning System (GPS) suffered an unexplained interference, triggering an emergency diversion.The Boeing 737 MAX 8-200 had already descended to around 850ft (259m) when the disruption occurred. Instead of landing, the plane was forced to climb back ...