Boeing is in talks with four airlines on orders for its redesigned 777X jetliner valued at as much as $87bn (€63bn) ahead of next month's Dubai Airshow, sources have said.
The 255 planes under discussion are said to include 100 to 150 for Emirates, 50 for Qatar Airways, and 30 for Etihad.
An order haul in Dubai for the 777X would be a boost for Boeing years ahead of the jet's commercial debut, now targeted for about 2020.
Boeing is betting that it can keep Airbus at bay in the market for the biggest twin-engine jets by upgrading the 777, not by building an all-new plane as its rival is doing with the A350.
"This kind of order would definitely be a huge vote of confidence in the aircraft," said Siyi Lim, an analyst at OCBC Investment Research. "The 777 is already a proven aircraft and most airlines already fly them."
Success with the 777X comes after Boeing's troubles earlier this year with the 787 Dreamliner, when it was grounded for three months. For the 777X, Boeing is adding 50 more seats to the largest current 777 variant so it can seat as many as 400 people. It will feature the biggest-ever engines and a wider, fuel-saving wingspan.