American Airlines is in a system-wide ground delay until 5 p.m. because of problems accessing its reservations system.
“American's network system is experiencing intermittent outages," the airline wrote on its Facebook page. "We apologize to our customers for any inconvenience."
The airline later posted it was unable to make changes to Tuesday's reservations until the issue was resolved. American plans on offering full refunds or assisting in updating travel plans at no charge.
Several people reported waiting on planes for up to two hours.
Half a dozen American Airlines planes were waiting on the runway at Miami International Airport. Others sat at gates.