"It's the first JV in the country," says Enrique Cueto on the sidelines of the ALTA Airline Leaders Forum in Mexico City. "It's new for any authority. People don't understand."

Brazil's competition regulator CADE recently raised competition concerns over the proposed joint venture between LATAM and IAG, pointing out that the deal could hinder competition on two European routes from Sao Paulo: London and Madrid. CADE's tribunal has the final say on whether to approve the deal.

Cueto says LATAM is in talks with the regulator to see what can be done in terms of concessions. He points out that other airline joint ventures have been approved after the parties agreed to certain conditions.

LATAM is also planning a JV with American Airlines, but the deal is not being looked at by CADE as yet, because Brazil's congress has not ratified open skies with the USA.

Cueto could not say when Brazilian approval of the open-skies will take place: "I hope it's soon."

LATAM is part of the oneworld alliance with American and IAG. Separately, it is also drawing closer to another oneworld member, Qatar Airways, which is acquiring a stake of up to 10% in LATAM through the issuance of new shares.

Cueto says he expects the transaction to close in December, or at the latest January 2017.