The Federal Aviation Administration has struggled to modernise long-standing elements of air traffic control, a report said.
The US government flight agency's multi-billion dollar Next Generation Air Transportation System infrastructure project has previously had several issues, according to a 2021 report by the Office of the Inspector General in the Transport Department.
Thousands of domestic US flights were delayed or cancelled on Wednesday after planes were grounded over a malfunction in a key system used by pilots before take-off.
US airlines such as Delta Air Lines, United Airlines and Southwest Airlines said they expected operations to return to normal on Thursday as FAA worked to find the cause of the outage.
“Our preliminary work has traced the outage to a damaged database file,” the FAA said in a tweet on Wednesday evening. “At this time, there is no evidence of a cyber attack.”
The 90-minute stoppage disrupted more than 11,000 flights. It was caused by a problem with an alerting system that sends safety messages for pilots.
Such a breakdown of a key computer system is not the first to hit FAA operations amid efforts to upgrade technology, Reuters reported.
The glitch occurred less than two weeks after a different critical air-traffic control system caused flight delays at major airports in Florida.
The OIG said its work “has shown that FAA has struggled to integrate key NextGen technologies and capabilities due to extended programme delays that caused ripple effect delays with other programmes”.
In October, for example, the FAA said it was working to end a long-ridiculed, decades-old practice of air-traffic controllers using paper flight strips to keep track of aircraft. But adopting the change at 49 major airports will take the FAA until late 2029.
The FAA has also been trying to modernise the Notices to Air Missions system “to improve the delivery of safety critical information to aviation stakeholders”, its website said.
The system provides pilots, flight crews and other users of US airspace with relevant, timely and accurate safety notices.
“I just learnt that my flight was delayed again,” said Vince Hamilton, who was at Reagan National Airport near Washington seeking to travel to Chicago, and then on to St Louis.
“I have to catch a bus that I'm probably going to miss.”
Travel industry officials said the issue highlighted key vulnerabilities in US infrastructure.
“Today's FAA catastrophic system failure is a clear sign that America's transportation network desperately needs significant upgrades,” US Travel Association President Geoff Freeman told AFP.