Imagine being in an aircraft at 30,000 feet when suddenly the plane pitches down and takes a nosedive towards the ocean. Or that the autopilot takes its own descending path against the will of the pilots and crashes at the end of the runway. Sounds like sci-fi?  No, these events have already happened. And they are likely to occur more as the aircraft industry braces for a new era in air passenger transportation: unmanned flights.

Belgian journalist Tom Dieusaert investigated several high-profile accidents wherein the plane’s on-board computers went crazy on the pilots: Air...