US aircraft maker Boeing is expected to announce a major deal to supply Qatar Airways with widebody jetliners.
The sale could be worth as much as $18bn (£14.5bn), the BBC understands.
If finalised, it would give Boeing a boost in a year when orders for widebody planes have slumped.
The deal comes as Qatar has been frustrated over prolonged delivery problems from European Boeing rival Airbus.
Media reports last week suggested the deal was for at least 30 Boeing 777 and 787 jets, valued at about $6.7bn.
The final deal though is thought to also include orders for the Boeing 737 MAX jetliners.
Analysis: Michelle Fleury, New York business correspondent
The ongoing fight between Qatar Airways and Airbus has turned nasty – with Boeing emerging as the big winner.
The chief executive of the Gulf carrier, Akbar Al Baker, is a forthright individual. He has previously described his airline’s relationship with Airbus as “strained” because of delivery delays and engine problems with the Airbus A320neos.
Now Akbar Al Baker is making sure Airbus pays the price, with a big order for its American rival. The mega deal is not just a financial winner for Boeing. It’s also a huge boost for the US planemaker’s single aisle 737 MAX aircraft.
It is the US aerospace giant’s newest plane and doesn’t go into service until next year.
And politics may also be at play.
There was a suggestion that the Qatar government may have delayed the Boeing passenger jet order to put pressure on the US to approve a deal for Boeing fighter jets to the Middle Eastern country – a deal which the Americans now look set to approve.