Garuda Indonesia will decide on whether to order Boeing 747-8 Intercontinental or Airbus A380 aircraft by the end of the year.
The airline is evaluating both types as replacements for its two 747-400s, which are mostly used on services to Jeddah for the Haj and Umrah pilgrimages.
"Right now our team is looking at it, which is more efficient for us. We've got all the data, we've got all the information," says chief executive Emirsyah Satar in an interview.
"Honestly, I think it will be by the end of this year that we will decide what we want."
Emirsyah says that both aircraft are capable of being reconfigured from an all-economy layout to a two-class layout in two weeks, which would allow the airline to deploy the aircraft on other services when they are not being used for the pilgrimages.
China and Japan are markets that could make use of the additional capacity during the off-peak periods, he adds.
More immediately, Garuda will deploy its 314-seat, three-class configured Boeing 777-300ERs on its services to Jeddah from 9 July.
Emirsyah adds that the airline would like to fast track the delivery of its 777s. The airline will take delivery of four this year, two in 2014 and the remaining four in 2015, but would like to receive more in 2014.
"We're trying to move faster next year, it depends on the production line of Boeing. We would prefer to make it sooner," he says.
Although the airline's fleet has an average age of less than six years, Emirsyah says that Garuda is "in the midst of finalising our fleet plan until 2025."
He adds that this includes looking at possible replacements for types such as the A330 and 737-800, which are still being delivered.
Flightglobal's Ascend Online database shows that Garuda operates a fleet of 96 aircraft and has a further 57 on order.