WICHITA, Kan. (KSNW) – The Federal Aviation Administration has lifted a ground stop on flights across the U.S. following a computer outage.

The FAA lifted the stop shortly before 8 a.m. CT. The agency said that normal air traffic operations were resuming gradually across the U.S. following the outage.

According to Wichita’s Dwight D. Eisenhower National Airport, several flights that were delayed eventually took off. However, the impacts of the ground stop will be felt throughout the country because of the delays this morning.

Whatever the cause, the outage revealed how dependent the world’s largest economy is on air travel, and how dependent air travel is on an antiquated computer system called the Notice to Air Missions, or NOTAM.

Before commencing a flight, pilots are required to consult NOTAMs, which list potential adverse impacts on flights, from runway construction to the potential for icing. The system used to be telephone-based, with pilots calling dedicated flight service stations for the information, but has moved online.

The NOTAM system broke down late Tuesday, leading to more than 1,000 flight cancellations and 7,000 were delayed flights by midday Wednesday, according to the flight tracking website FlightAware

While the White House initially said that there is no evidence of a cyberattack, President Joe Biden said “we don’t know” and told reporters he’s directed the Department of Transportation to investigate the cause of the disruption.

U.S. Senator Jerry Moran, along with his co-chair of the Senate Travel and Tourism Caucus Amy Klobuchar, released a statement:

Travelers in the United States deserve safe and dependable air travel service. As co-chairs of the Senate Travel and Tourism Caucus, we had a constructive conversation with FAA Acting Administrator Billy Nolen who said that his agency is working to determine what caused today’s breakdown to ensure it doesn’t happen again. We are committed to working together in a bipartisan way to strengthen and modernize our air travel system and meet the demands of our 21st century economy.”

Moran and Klobuchar

The Associated Press contributed to this report