Southwest Airlines Co (LUV.N) has extended the cancellation of Boeing’s 737 MAX planes from its flying schedule until Oct. 1, the U.S. airline said on Thursday.

The airline had previously planned to keep the jet, grounded in March after a second fatal crash in five months, off its flying schedule through Sept. 2.

The extension comes after the Federal Aviation Administration on Wednesday said it has identified a new potential risk that Boeing Co (BA.N) must address on the planes before they can return to service.