Singapore Airlines (SIA) has entered into a letter of intent with Boeing to purchase 39 wide-body aircraft for $13.8bn.

Comprising 20 777-9 and 19 787-10 Dreamliner aircraft, the order is intended to grow and modernise SIA’s fleet through the next decade.

It also includes six options for each aircraft type, which will increase the deal up to 51 aircraft if exercised.

As part of the new deal, SIA also has the flexibility to substitute the 787-10 orders for other variants of the 787 family aircraft.

“This order is also another demonstration of our commitment to further growing the Singapore hub."

Delivery of the newly ordered 777-9s is scheduled to be started from the 2021/2022 financial year, while the delivery of 787-10 aircraft is set to begin from 2020/2021 fiscal.

Singapore Airlines CEO Goh Choon Phong said: “Today’s major order for widebody aircraft enables us to continue operating a modern and fuel-efficient fleet, providing the SIA Group with additional expansion opportunities to ensure that we retain our industry-leading position.

“We are continuing to invest for the future of the SIA Group.

“This order is also another demonstration of our commitment to further growing the Singapore hub, as we will be able to offer even more travel options for our customers.”

The 777-9s to be delivered to SIA will be equipped with General Electric GE9X engines and used to serve long-haul routes.

SIA has selected the Rolls-Royce Trent 1000 engine to power the newly ordered 787-10s, which will be operated on medium-range routes.

In 2013, SIA placed an initial order for 30 Boeing 787-10 Dreamliners, which is currently undergoing development.