Azul SA's pursuit of a merger with Gol Linhas Aereas Inteligentes SA has gained momentum, with talks underway for a deal with the controlling shareholder of the rival Brazilian airline, according to people familiar with the matter.

In one scenario under consideration, holding company Abra Group Ltd. would contribute its Gol shares to Azul in exchange for a stake in the combined airline, one of the people said, asking not to be identified because discussions are still private. That type of transaction could appeal to Azul because it wouldn't have to commit much cash, if any, another person said.