Proposed deal includes the carrier's first Boeing 787s alongside additional Airbus A350-1000s

Flag carrier would become the alliance's 16th member and only the second full member based in Southeast Asia

The carrier has an order for nine A350-1000 aircraft that will replace the Boeing 777-300ER on long-haul flights

Carrier had signed a Memorandum of Unerdstanding in May. Aircraft will have 380 seats and will join the A350-900 already in service