@Moon @bronze
I'm afraid that airplanes are not as well protected as they should be. In particular, the now ubiqutous flight management connectivity is a serious weak link. Every pilot must carry a tablet nowadays. By cracking that tablet, one can get into the app like Jepp, and jump to a navigator. On a plane that has Garmin Autoland it's basically a direct access to flight controls. In a world where Israelis were able to jump air gapped systems and infect PLCs in order to blow up Uranium refinement centrifuges, crashing airliners should be easy, it's just nobody got around to doing it. Crashing my own airplane this way might be harder, because its engine and flight controls are not computerized, but one can for example direct me to nowhere and make me get lost and run out of fuel by screwing with the navigation software (theoretically speaking, of course - I mostly fly VFR).