American, the largest airline in the world, operates 24 737 MAX aircraft. Southwest Airlines Co, which has the world's largest 737 MAX fleet with 34 jets, said it was waiving any fare-difference charges for customers who were seeking to switch to another aircraft following bans across much of the world.
The low-cost airline already does not charge a fee for changing tickets. The company said it is also waiving charges for fare differences following customer concerns about traveling on the jets. American said it was notified by the Federal Aviation Administration (FAA) of its decision to ground the jets earlier on Wednesday.
(Reporting by Tracy Rucinski Editing by Chizu Nomiyama and Nick Zieminski)