By the runway, a brand new air traffic control tower needed to be built.

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But some security researchers imagine a less sensational, if equally troubling possibility: Hundreds or thousands of aircraft radioing their approach to an air traffic control tower, and no way to sort through which are real and which are ghost plane signals crafted by a malicious hacker.

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Petersburg airport's air-traffic control tower, which then notified Tampa International Airport, Tampa police said.

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The city's international airport was also closed to flights at one point, and staff began building a temporary control tower, as air traffic facilities were switched to emergency power sources.

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Aviation experts contend that even if intruders were able to access a control tower and disrupt operations, the nation's air traffic control system is designed with multiple back-ups so that other facilities could pick up control of the affected air space.

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Tower closures would not necessarily result in airport closures, because some aircraft can land without air traffic control help, and those that need controller help can communicate with more distant FAA facilities.

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