He started his new job at 7:30 AM. By 9:45 AM, he grounded America.

On September 11, 2001, the United States made an unprecedented decision. Every civilian aircraft in American airspace had to land immediately.

This video follows the events minute by minute as air traffic controllers, pilots, military commanders, and government officials struggled to understand what was happening. Hijacked planes had already struck the World Trade Center and the Pentagon, while thousands of other aircraft remained in the sky. FAA National Operations Manager Ben Sliney, on his very first day in the job, ordered a nationwide ground stop and then made the extraordinary call to clear the entire sky. More than 4,500 aircraft had to be brought safely to the ground while internat…