Australia's Qantas Airways has ordered five additional Boeing 737-800 aircraft and extended the leases on two existing 737-800s for domestic operations.
The new aircraft will be delivered in 2014, says the Oneworld alliance member.
In addition, the airline will reconfigure the interior of 10 Airbus A330-300s and 20 A330-200s with a new flat seat in business class, revamped economy cabin and a new in-flight entertainment offering. The reconfiguration will start in late 2014.
Qantas International will use the A330-300s on its routes between Australia and Asia.
The A330-200s will be deployed by Qantas Domestic on routes between Australia's east coast and Perth, says the airline, adding that the change is expected to allow the final retirement of its Boeing 767s.
The airline's older 737-400s will be phased out by the end of 2013 and the 767s, by mid-2015.
"There will also be cost savings, because the A330 and 737-800 are more fuel efficient and require less frequent heavy maintenance than older aircraft types," says Qantas chief executive Alan Joyce.
"Together with our recent announcement of orders for five additional Boeing 717 aircraft and three additional Bombardier [Dash 8] Q400s for regional operations, the changes we've outlined today will ensure that we have the right fleet in every part of the international and domestic market."
The airline adds that the A330 reconfiguration programme and 737-800 orders do not affect its planned capital expenditure of A$1.6 billion ($1.64 billion) in fiscal year 2012/13 and A$1.5 billion in fiscal year 2013/14.