Heavy travel day starts with brief grounding of all American Airlines flights

abcnews.go.com:

American Airlines briefly grounded flights nationwide due to a technical problem just as the Christmas travel season kicked into overdrive and winter weather threatened more potential problems for those planning to fly or drive

WASHINGTON — American Airlines briefly grounded flights nationwide Tuesday because of a technical problem just as the Christmas travel season kicked into overdrive and winter weather threatened more potential problems for those planning to fly or drive.

Government regulators cleared American flights to get airborne about an hour after the Federal Aviation Administration ordered a national ground stop for the airline. The order, which prevented planes from taking off, was issued at the airline's request after it experienced trouble with its flight operating system, or FOS. The airline blamed technology from one of its vendors.

As a result, flights were delayed across American’s major hubs, with only 37% of the airline's 3,901 domestic and international flights leaving on time, according to Cirium, an aviation analytics company. Nineteen flights were canceled.

Dennis Tajer, a spokesperson for the Allied Pilots Association, a union representing American Airlines pilots, said the airline told pilots at 7 a.m. Eastern that there was an outage affecting the FOS system. It handles different types of airline operations, including dispatch, flight planning, passenger boarding, as well as an airplane's weight and balance data, he said.

Some components of FOS have gone down in the past, but a systemwide outage is rare, Tajer said.

Hours after the ground stop was lifted, Tajer said the union had not heard about any “chaos out there beyond just the normal heavy travel day.” He said officials were watching for