American, the largest U.S. airline, had previously cancelled about 140 flights a day through March 4 and now expects to resume 737 MAX passenger flights on April 7.

Once the FAA gives 737 MAX approval, American will need at least 30 days to prepare the jets and its pilots for commercial flights, airline and union officials have said.

Boeing 737 MAXs have been grounded worldwide since March following an Ethiopian Airlines Co crash, the second of two fatal crashes in five months that killed 346 people. Southwest Airlines Co Chief Executive Gary Kelly said earlier Thursday it was "likely" the carrier would need to extend its cancellations beyond early March.

(Reporting by David Shepardson; Editing by Richard Chang)