Support Grows to make Jets Tamper-Proof
"Lacking clear-cut answers about the disappearance of Malaysia Airlines Flight 370, aviation industry leaders are looking for ways to prevent key safety and communications systems from being disabled by anyone on commercial airplanes in the future. Potential changes include making satellite-messaging systems and transponders that communicate with air-traffic-control radar virtually tamper-proof............
........The primary goal is to make it practically impossible for flight crews or passengers to turn off electrical power to these devices in midair by removing circuit breakers now normally accessible in the cockpit."
Support Grows to Make Jets Tamper-Proof - WSJ.com
Seems that there are those that see access to the communications capabilities to be a hole in security.