Airbus has lost a valuable order for its new line of A350 jets after Emirates Airlines cancelled its plans to purchase 70 planes — an order worth about $16 billion — the European aerospace company said Wednesday.

The change of heart by Emirates represents the biggest-ever order cancellation for Airbus. Dubai-based Emirates originally ordered 50 A350-900 and 20 A350-1000 aircraft in 2007, and the first deliveries were scheduled to hit runways in 2019.

“The contract which we signed in 2007 for 70 A350 aircraft has lapsed,” said an Emirates spokesperson. “We are reviewing our fleet requirements.”

The change comes in the wake of Emirates decision to add 50 A380 jets to its collection last year, becoming the largest operator of the superjumbo Airbus planes. The airline is also the lead buyer for Boeing’s new 777X, a similar twin-engined, wide-body plane that is due for delivery shortly after the A350s.

Airbus’ new jets have been under development for eight years to the cost of about $15 billion. The European aircraft maker said it was “very confident” in the A350 program, which is set to enter into service in six months. There are “a healthy 742 firm orders” still set, and Airbus expects the order book to continue growing this year, replacing the lost Emirates orders.