The proof of this is that the Feds took it seriously enough to pull the guy off the flight and grill him for hours.
Much the same way that the proof of the center fuel tank explosion was the way the fleet was promptly grounded for inspections ad repairs.
The guy was on the plane with a variety of computer equipment trying to prove his point. He was trying to do something that might be dangerous. The hell with the rest of the passengers who might be affected by an ‘oops’ he might have had.
No, the Feds don’t know squat. They simply have treat each threat as possible.
This is a bogus claim. Period. My airliner is shielded for EMI, and no part of my systems can be accessed without plugging into a encrypted data stream, which is only accessible through a single proprietary port physically located next to my left hip. Unhackable, just like every computer that is NOT attached to a network.
The Internet and wireless on my airliner is an after market setup that other than electrical power is completely separate from the actual aircraft systems.