Irish airline Ryanair has ordered 75 more Boeing 737 Max aircraft on top of the 135 units it agreed to buy, pushing its order value to $22 billion.
Ryanair would take delivery of the planes early next year.
The US Federal Aviation Administration has certified the return to service of the Boeing 737 Max, which was grounded in March 2019.
However, the European Union Aviation Safety Agency (EASA), which is in charge of re-certification for EU member states and the UK, has not approved Boeing 737 Max's return to service.
According to Ryanair's Michael O'Leary, the 737 Max is a game-changer, more efficient than older models, and more environmentally friendly.
O'Leary swears that the 737 Max is a fabulous aircraft and that passengers would love it.
Boeing took the 737 Max out of service after two crashes five months apart, which together killed 346 people.
To receive clearance to fly again, Boeing made a series of modifications including, updating flight control software, rerouting internal wiring, and revising crew procedures.
Boeing CEO David Calhoun said the Ryan Air orders was the beginning of "a more robust order book".
The price of the transactions wasn't disclosed, but Ryanair will benefit from a supposedly "modest" discount on the cost.
Calhoun emphasized that Boeing did not feel a need to discount prices to bring back customers.