Amanda Bynes tried to force a ticket agent into re-routing a plane ... just so she could fly across the country STAT -- and because of it, Amanda got swiftly booted from the airport.
As we previously reported ... Bynes was ordered out of LaGuardia airport for screaming at a ticket agent Friday morning -- so she booked it to JFK to try to catch another flight.
Law enforcement sources say the shouting match was all because Amanda wanted a direct flight as soon as possible ... and wouldn't listen to the agent explain that planes have a specific route.
We're told things got so bad airport authorities had to step in to escort Bynes out of the building -- putting her into a cab outside to send Amanda on her way.
Amanda's parents are still trying to locate the actress so they can attempt to put her into a treatment facility.