9/11

The hijackers had taken flying lessons and trained on flight simulators for their suicide mission to turn civilian airliners into giant guided missiles laden with jet fuel, targeting the most potent symbols of American economic, military and political might.

But it turned out that they did not know how to operate the planes' radio and intercom systems and so they inadvertently broadcast messages that were intended to deceive the passengers to air traffic controllers.

The voices from the doomed aircraft were detailed in the 9/11 Commission Report in a dramatic opening chapter entitled "We have some planes", the first alarming words heard from a terrorist.