Boeing has received strong demand for the much-anticipated launch of its 737 MAX single-aisle aircraft at the Paris Air Show on Monday, as the maker of F-18 fighter jets stepped up its rivalry with Airbus.

The defense and passenger jet maker announced an order for 20 737 MAX 10 jets from GE Capital Aviation Services, the commercial aircraft leasing and financial arm of General Electric. It also received orders for 10 737 10 Max planes from BOC Aviation valued at $1.25 billion. And tour operator TUI ordered 18 737 10 Max jets.

“Simply put, the 737 MAX 10 will be the most profitable airplane the single-aisle sector has ever seen,” Kevin McAllister, Boeing commercial airplanes president, said in a statement.

Boeing’s new 190-230 seat 737 MAX 10 airplane is a response to Airbus’ A321neo – the hugely popular narrow-body passenger jet. However, the race between Boeing and Airbus for orders at the Paris Air Show may be of less importance as both plane makers focus on how to get through their massive backlog of orders.

Speaking on the sidelines of the Air Show, Boeing CEO Dennis Muilenburg explained the firm currently has more than 4,000 737 airplanes in backlog. Boeing’s CEO added the company hoped to ramp up aircraft production from 42 airplanes a month in 2017 to 57 a month by 2019.

“Against that increase in production profile, we are actually oversold… so we continue to feel very strongly about the airplane and now, as we feather in the 737 MAX 10, we’re adding even more value into the market place,” Boeing’s Muilenburg told CNBC.