Two American Airlines flights are grounded at San Francisco International Airport, causing delays for about 300 passengers on one of the airport’s biggest travel days this season, airport duty manager Lily Wang said.

A 6 a.m. flight from SFO to Dallas was canceled, and passengers were booked on the airline’s 10 a.m. flight instead. Another American flight, at 7 a.m. to Miami, had mechanical problems and was delayed until approximately 11:30 a.m.