Travelers across the country faced the prospect of canceled or delayed flights on Saturday as airlines and airports dealt with a combination of high demand, bad weather and staff shortages.

As of Saturday evening, nearly 650 flights in the United States had been canceled and more than 5,200 flights within, to or from the country had been delayed, according to flight tracking website FlightAware.

While the number of problem flights was higher than on a typical travel day, travel demand was also higher. According to the Transportation Security Administration, the number of travelers over the July 4 holiday weekend had reached pre-pandemic levels. Demand for travel over the same holiday weekend last year had recovered significantly from pandemic lows, but was still below this year’s levels.

FlightAware data showed the three US airports most affected by cancellations and delays on Saturday were Dallas-Fort Worth International Airport and Kennedy Airport and Newark Liberty International Airport in the Dallas area. New York.

The number of canceled and delayed flights was well below the levels of the last Christmas and New Year holidays, when bad weather and Omicron-related staff shortages disrupted airline schedules.

Yet airlines are scrambling to keep up with demand this July 4 holiday as they grapple with a shortage of pilots, weather conditions and air traffic control delays.

“Delta crews continue to safely manage the aggravating factors of inclement weather and air traffic control delays, which impact available flight crew duty time,” a Delta Air spokesperson said. Lines in an email. “Flight cancellation is always our last resort, and we sincerely apologize to our customers for any disruption to their travel plans.”

Delta said it is offering customers the option to reschedule flights from July 1 to July 4 with no fare change if they are traveling between the same origin and the same destination.

United Airlines also blamed weather and air traffic control programs for the delays.

Adding to American Airlines’ stress was a computer glitch in its pilot travel exchange system which the airline says allowed travel exchanges that “shouldn’t have been allowed”. But American said it “does not anticipate any operational impact from this issue” and added that the “primary drivers of delays/cancellations” on Saturday were “weather and traffic control issues.”

The Federal Aviation Administration said the leading cause of flight delays and cancellations was weather, followed by travel demand. The agency added in a statement, “The FAA has acted on issues raised by airlines and is working with them to share information to keep planes moving safely when weather and other adverse events occur. airspace limit capacity. The agency also added alternate routes and placed more controllers in high-demand areas, and increased data sharing.