AMR Corporation and US Airways Group Inc have started building the new American Airlines, as the merger between the two companies has been completed to officially form American Airlines Group Inc, the companies announced on Tuesday.

The new American Airlines, offering almost 6,700 daily flights to more than 330 destinations globally, is the largest carrier in the world and the process to achieve a single operating certificate is expected to take 18 to 24 months.

The merger is expected to generate more than $1 billion in annual net synergies by 2015, the companies said in a statement.

Meanwhile, US Airways will exit Star Alliance on March 30, 2014, and enter Oneworld Alliance on March 31, as American Airlines is one of the founder members of Oneworld Alliance.