A technical glitch at an outside aviation company led to delays at major U.S. airlines.
The issue was resolved quickly, but it led to travel disruptions Monday. Delays that began appearing first in Chicago, New York, Miami and Boston spread to Dallas, Atlanta, Detroit and Washington, D.C.
The Federal Aviation Administration said several airlines had problems with a program called Aerodata, which is used to plan weight and balance for flights. The FAA said the issue was resolved.
By midday, 3,400 U.S. flights had been delayed, according to tracking service FlightAware, but it was unclear how many were related to the technical issue.
The FAA advised travelers to contact airlines directly for flight information and updates. Airlines said travelers should check online for the latest updates on flights.
American Airlines said the technical issue affected a few of its regional carriers that operate American Eagle flights.
Southwest Airlines lifted an internal ground stop at on Monday morning after about 40 minutes. Nearly 1,000 Southwest flights had been delayed by midday, according to FlightAware.
Some United Airlines regional carriers were hampered by the issue, which resulted in delays for select United Express flights, the company said. About 150 flights were impacted, according to United.
"Some flights that were affected have departed, and we're working to get all affected flights back on schedule," United said.
Delta said that the outage prevented some of its Delta Connection flights from leaving on time. The airline did not anticipate flight cancellations.