DUBAI, UAE - One of the busiest and more travelled airlines in the world has placed an $8.8 billion order for the delivery of thirty Boeing 787-9 Dreamliners.

The order was announced by Emirates Chairman and CEO Sheikh Ahmed bin Saeed at the Dubai Air Show on Wednesday.

As part of the order, Emirates will substitute some 777Xs on order with 787-9s.

Deliveries are expected to commence by May 2023.

"The 787s will complement our fleet mix by expanding our operational flexibility in terms of capacity, range and deployment to connect new city pairs and expand frequencies," the Emirates chairman said Wednesday.

Emirates had previously placed an order for forty Dreamliners in 2017 but the order has not been completed.

Emirates said it will talk to Boeing regarding the status of 777X deliveries in the next few weeks.

"We want to introduce it to perhaps thinner routes where 787 comes into its own on both medium and long haul operations," Tim Clark, the president of Emirates said. "The sooner we get that the better, so we decided to exercise the right to get them in sooner."

The airline has 18 months to two years before it needs to make a decision, he said.

"By the early 2020s, Emirates will restart its expansion in no uncertain terms and we can do this with these aircraft, including the 777X programme when it comes in," Clark added.

"It's a holistic approach for the growth of the Dubai hub with the two airlines, it makes sense and because it worked so well for us so far with flydubai, cross-flows, we realised we should be looking into things like the 787 and a350."

Airbus signed Emirates to an order for fifty A350-900 wide-bodied aircraft worth $16 billion on Monday taking its total commitment in three days for new aircraft to $24.8 billion.