President Trump was briefed within 30 minutes of the Federal Aviation Administration ordering a nationwide ground stop Friday afternoon, according to U.S. officials.
The ground stop triggered thousands of flight cancellations and left travelers stranded across the country. The FAA ordered all aircraft to remain on the ground at 3:36 p.m. ET, even as roughly 3,500 flights were already airborne.
Within minutes, the FBI, the director of national intelligence, the Department of Homeland Security, the Transportation Department, the Justice Department, the Defense Department, the Joint Chiefs of Staff, U.S. Cyber Command, the FAA and the Federal Emergency Management Agency began coordinating on the incident.
Transportation Secretary Sean Duffy said in a statement at 4:16 p.m. ET that the ground stop was required because of “a communication issue impacting all Air Route Traffic Control Centers.” FAA technicians, he said, were investigating. Soon afterward, the White House convened a call with the agencies to establish what had gone wrong and determine a response.
After reviewing intelligence channels for suspicious communications or other indications of an attack, the intelligence community preliminarily concluded that malicious activity was unlikely. Officials found no such evidence.
Senior aides briefed Mr. Trump, who was attending an economic policy meeting, according to a U.S. official. His instructions were then relayed to the other participants on the multi-agency call, which was led by White House chief of staff Stephen Miller.
Mr. Trump later met with Duffy and DHS Secretary Markwayne Mullin.
Shawn Thew / EPA / Bloomberg via Getty Images 
Mr. Trump also began contacting congressional leaders Friday to seek additional funding for the FAA. The White House congressional affairs team reached out to key lawmakers about modernizing the nation’s air traffic control system.
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The Homeland Security Council invited senior government officials and several outside stakeholders to a Monday meeting focused on next steps and measures to prevent a similar disruption while modernization work continues.
The council is an interagency body that coordinates national homeland security policy. President George W. Bush established it in 2001. Under the current White House structure, it operates within the National Security Council framework and can draw on senior officials from the Transportation Department, FAA, DHS and Defense Department.
Not every aircraft was affected by the four-hour ground stop. Flights carrying out medical services were authorized to continue to their destinations.
By the fourth hour, officials had identified the system problem and lifted the ground stop. FlightAware reported that approximately 9,159 flights were canceled and 7,190 delayed Friday.
At a Saturday news conference, Duffy said the disruption apparently began while FAA telecommunications contractor L3Harris Technologies was performing maintenance at a remote facility. The work involved replacing aging copper communication lines with fiber-optic connections. During the updates, a router began generating more than 1,000 connection attempts every four to five seconds, overwhelming routers throughout the FAA network.
Mullin and Duffy arrived more than 30 minutes late for a 7:45 p.m. ET news conference Friday because they were close to lifting the ground stop and did not want to disrupt the effort, according to U.S. officials.
Although federal officials have identified a likely chain of events behind Friday’s aviation disruption, important questions remain about the underlying cause of the systemwide failure.
