Boeing Co., which has been working for three months to put its troubled 737 Max back in the air, won a tentative agreement Tuesday from British Airways parent International Airlines Group to buy 200 of the airliners, worth $24 billion.

The Max, the latest iteration of Boeing’s widely flown 737 single-aisle jet, has been grounded worldwide since March after two overseas crashes that killed more than 300 people. Both disasters were linked to new anti-stall software that erroneously activated during takeoff, authorities said, and the Chicago-based planemaker is now seeking Federal Aviation Administration approval of a patch to address the issue.