American Airlines has cancelled all its MAX flights through to mid-August as it waits for Boeing to upgrade software but says it's confident the fix will work.
American Airlines is cancelling 115 flights a day through mid-August because of ongoing problems with the Boeing 737 MAX aircraft.
The cancellations represent 1.5 per cent of American's total flights each day of the (northern) summer.
The US grounded Boeing's 737 MAX plane in mid-March after two deadly plane crashes.
Boeing has been developing a software upgrade for an anti-stall system under scrutiny in both crashes. The plane-maker aims to finish fixing the planes in late April, and changes would have to be submitted to the Federal Aviation Administration and foreign regulators for approval.
American has 24 MAX jets and had previously planned to cancel MAX flights through early June. Airline officials say by extending cancellations through the summer they can plan more reliably for the peak travel season.
In a letter to employees and customers, chief executive Doug Parker and president Robert Isom said they believe the 737 MAX will be recertified before August 19, but they want to ensure reliability "for the peak travel season and provide confidence to our customers and team members when it comes to their travel plans".
Parker and Isom said they are "confident" in Boeing's impending software updates and new training proposals, and remain in continuous contact with regulatory authorities over the MAX recertification process.
Once the aircraft is recertified, which the executives said they expect will happen "soon", American plans to initially bring its MAX aircraft back on line as spares to supplement its operation as needed during the summer.
The airline says its reservations and sales teams will work with customers to manage their travel plans.