air traffic control system

The air traffic control system that choreographs the roughly 7,000 aircraft in U.S. skies at any given moment is the most complex, but also one of the safest, in the world -- and rarely a thought in the minds of the millions of travelers who rely on it.

The nation's system for guiding planes and other aircraft is at "increased and unnecessary risk" of being hacked, according to a report by government watchdog released Monday.

A high-tech overhaul to the nation's air traffic control system is mostly on track to completion, but has yet to produce the benefits that airlines and passengers were told to expect, federal investigators say.