With the Federal Aviation Administration’s (FAA) alert system outage in the rearview mirror, more flight disruptions could be on the way in 2023. The FAA released a statement explaining the outage Thursday, saying it was caused by contracted workers “unintentionally” deleting files used for the system.

“The FAA made the necessary repairs to the system and has taken steps to make the [Notice to Air Missions] system more resilient,” the FAA said in the statement. “The agency is acting quickly to adopt any other lessons learned in our efforts to ensure the continuing robustness of the nation’s air traffic control system.”

In the statement, the FAA added it “has so far found no evidence of a cyber-attack or malicious intent.” The agency added it is still investigating.

The FAA outage statement comes as one airline CEO warned there may be more flight disruptions for travelers. Speaking on a call with analysts and reporters this week, United Airlines CEO Scott Kirby said airlines won’t be able to handle all the flights they plan to operate this year.

“The system simply can’t handle the volume today, much less the anticipated growth,” Kirby said. “There are a number of airlines who cannot fly their schedules. The customers are paying the price.”

Kirby noted the industry is dealing with a shortage of pilots and other workers, outdated technology and strains on the FAA. He cited not only last week’s outage, but the thousands of weather-related cancellations in recent weeks, as why there needs to be more resources given to the aviation industry.

“This isn’t a partisan issue. This isn’t Democrat, this isn’t Republican. This is infrastructure,” Kirby told CNBC this week. “If we do this, reducing delays, cancellations, all the downline implications that has for the economy, this is one of the easiest paybacks out there.”

Southwest Airlines was one of the largest victims of last month’s winter storms. The airline may also have to deal a further lack of pilots after the Southwest Airlines Pilots Association (SWAPA) called for a vote that would give the union the power to call a potential strike.

“I think it is best to consider what our customers have been through over the past several years and the past several weeks,” SWAPA President Capt. Casey Murray said in a Wednesday statement. “It was the lack of discussion or commitment by our leadership team to rectify these issues for our passengers and our pilots that drove us to make the decision to carry forward on this path afforded to us by the Railway Labor Act.”

SWAPA has sought federal mediation in their labor talks with Southwest, which have been ongoing for years. That mediation is scheduled to resume next week. If a deal isn’t reached, a strike vote would begin May 1.

The Associated Press, The Hill and CNBC contributed to this report.