Airline websites, including those for Delta Air Lines and United Airlineswere affected during Monday’s hourslong disruption of Amazon Web Services, the massive cloud computing provider, with some customers complaining they were unable to access flight check-in functions or their reservations.

At 5:27 a.m. ET, Amazon said: “We are seeing significant signs of recovery. Most requests should now be succeeding. We continue to work through a backlog of queued requests. We will continue to provide additional information.”

The company had said earlier Monday on its AWS dashboard that its customers were experiencing “increased error rates and latencies for multiple AWS services in the US-EAST-1 Region.”

Some reservations were showing up on airline apps, while customers complained on social media that they couldn’t check in or drop off bags, for several hours.

United responded to a customer on X on Monday that it was “experiencing a system glitch affecting our online tools.”

United told CNBC some of its internal systems were temporarily affected by the outage and that it was using backups to end the disruption. The airline said “our teams are working to get our customers on their way.”

Delta said mid-morning it had some “minor” delays on Monday because of the outage but that it did not “anticipate any significant customer impact moving forward as a result of this event.”

A massive CrowdStrike outage in July 2024, due to a botched software update, took thousands of Microsoft Windows systems offline, disrupting air travel and other industries around the world. Delta said the disruption forced it to cancel more than 5,000 flights and cost it more than $500 million in revenue and compensation for passengers, among other expenses.

The disruptions on Monday occurred as the U.S. government shutdown stretches on. Staffing shortages of air traffic controllers, who are required to work though they’re not getting paid during the impasse, contributed to delays at major U.S. airports on Sunday, including in Dallas and Fort Worth, Texas; Chicago and Newark, New Jersey.

than 7,800 U.S. flights were delayed on Sunday, according to FlightAware, with staffing shortages, bad weather and other constraints contributing to the problems.

WATCH: Transportation Secretary Duffy on air travel disruptions due to the shutdown