WASHINGTON — On September 11, 2001, thousands of passenger and private aircraft were still flying across the United States as authorities struggled to determine how many planes had been hijacked. Then came an unprecedented FAA response: stop departures nationwide and bring civilian aircraft already in the sky safely to the ground.
At the center of the operation was Ben Sliney, the FAA’s National Operations Manager at the Air Traffic Control System Command Center. September 11 was his first day in that position, but Sliney was an experienced air traffic controller and FAA manager. The decisions made that morning ultimately helped bring roughly 4,500 commercial and general-aviation aircraft down without incident.
The story is receiving renewed attention in 2026 as the United States marks the 25th anniversary of the September 11 attacks and remembers both the victims and the extraordinary emergency response that followed.
The nationwide shutdown came in two major steps
The FAA did not clear American skies with a single initial command. The response escalated as the attacks unfolded.
At approximately 9:25 a.m. EDT, the FAA imposed a nationwide ground stop, preventing civilian aircraft waiting at airports from departing. By then, American Airlines Flight 11 had struck the World Trade Center’s North Tower at 8:46 a.m., followed by United Airlines Flight 175 hitting the South Tower at 9:03 a.m.
American Airlines Flight 77 struck the Pentagon at about 9:37 a.m.. With authorities unable to rule out additional hijackings, the response intensified.
At approximately 9:42 a.m., Sliney ordered FAA facilities to instruct civilian aircraft already airborne to land at the nearest suitable airport.
The 9/11 Commission hearing record described the nationwide landing order as unprecedented and said about 4,500 aircraft landed without incident.
Thousands of aircraft had to come down safely
The order created an enormous operational challenge. Controllers could not simply send every aircraft toward the ground at once. They had to maintain safe separation, identify appropriate airports and manage unexpected arrival traffic across the country.
Testimony presented to the 9/11 Commission said approximately 700 aircraft landed within minutes, followed by about 2,800 more during the next 50 minutes.
By 12:16 p.m., U.S. airspace had been cleared of commercial and private flights apart from military and essential emergency aircraft, according to the Commission.
The achievement was not Sliney’s alone. Air traffic controllers, FAA personnel, pilots, dispatchers, airline crews and airport workers across the country carried out the operation while information about the attacks was changing rapidly.
Flight 93 was still in the air during the shutdown
The danger had not ended when the nationwide landing order was issued. United Airlines Flight 93 remained airborne before crashing near Shanksville, Pennsylvania, at approximately 10:03 a.m. after passengers and crew members fought back against the hijackers.
That uncertainty helps explain the urgency behind removing other civilian aircraft from American skies: officials could not immediately know whether another aircraft represented a threat.
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Canada took in more than 33,000 diverted passengers
Closing U.S. airspace also affected international flights already heading toward America. Canada responded through Operation Yellow Ribbon, accepting diverted aircraft at airports across the country.
Canadian government records say 224 flights carrying more than 33,000 passengers were diverted to Canada.
Gander, Newfoundland and Labrador, became the most famous example. Thirty-eight international flights landed there, bringing more than 6,500 passengers into a community of roughly 10,000 people.
Residents, schools, churches and community organizations provided shelter, meals, transportation and other assistance. The experience later helped inspire the Tony-winning musical Come From Away.
9/11 permanently changed flying in America
The emergency landing operation solved the immediate problem, but commercial aviation remained heavily disrupted. Passengers were stranded, aircraft and crews were displaced, and flights resumed only gradually under heightened security.
Congress subsequently passed the Aviation and Transportation Security Act, signed into law in November 2001. It created the Transportation Security Administration and fundamentally changed how aviation security was handled in the United States.
Major aviation emergencies still demand coordination between crews, airports and federal agencies, as seen in the more recent Miami cargo plane crash investigation and black-box recovery. The September 11 response, however, remains exceptional because it involved the entire national airspace system.
Ben Sliney’s decision remembered 25 years later
Nearly 3,000 people were killed in the September 11 attacks. The 25th anniversary is bringing renewed attention to the victims, survivors, first responders and the decisions made while the scale of the attack was still emerging.
Those commemorations include the 25th-anniversary ceremony at the Pentagon, where Flight 77 struck just minutes before the FAA issued its unprecedented airborne landing order.
Sliney became the best-known figure associated with that decision, but the achievement depended on thousands of people throughout the aviation system. In a matter of hours, a sky filled with thousands of civilian aircraft was emptied safely during one of the most uncertain mornings in American history.
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