Qatar Airways has finalised a deal to buy 50 new generation 777-9X planes from US aircraft maker Boeing worth $18.9 billion (14 billion euros), the two firms announced on Wednesday.
The order was first announced as a commitment at the Dubai airshow in 2013.
Qatar added on Wednesday that it had agreed a commitment for 50 more of the long-haul fuel-efficient passenger jets, which if exercised would bring the total order value to $37.7 billion at list prices, the airline announced at the Farnborough airshow.
As well as buying up to 100 passenger jets, Qatar said it intended to purchase four 777 freighter planes with an option for four more.
In total, the 777 package is worth about $40 billion to Boeing.
"The Boeing 777 is the backbone of our fleet and is highly amenable to the standards Qatar Airways upholds. We look forward to building on our legacy with the next-generation 777-9X," said the airline's chief executive Akbar Al Baker.
Production of the 777X is set to begin in 2017, with first delivery targeted for 2020. Boeing has so far won 300 orders and commitments from six customers for the 777X.