American Airlines Group Inc. has become the second major U.S. carrier to pull the grounded Boeing Co. 737 Max from its flight schedule through the busy summer travel season, saying the decision will give passengers more certainty in making vacation plans.

The airline is pulling the Max through Aug. 19, Chief Executive Officer Doug Parker and President Robert Isom told the airline’s employees in a statement on Sunday. Southwest Airlines Co. last week removed the Max from its schedule through Aug. 5. The action will increase daily cancellations for American to 115 from about 90.

The Max was grounded March 13 after a second fatal crash involving the aircraft in five months. Boeing is working on proposed software updates that would prevent the repeated triggering of a system that can drive the plane’s nose down. U.S. safety regulators have to approve the fix and decide on new training for pilots.

“Based upon our ongoing work with the Federal Aviation Administration and Boeing, we are highly confident that the Max will be recertified prior to this time,” the executives said, referring to the Aug. 19 date. If that occurs, the American’s 24 Max planes would serve as spare aircraft to supplement operations over the summer, they said.

United Continental Holdings Inc. is the third U.S. carrier that operates the Max.