After its unveiling ceremony, the plane begins system checks, fueling and engine runs on the flight line.
If you were an airline planning to buy a lot of new single aisle jets Boeing's 737 MAX family might be of slightly confused interest this week.
Boeing said it is preparing to deliver its first Max 8s in the coming months.
The new Boeing plane is expected to enter service in 2020, said Tinseth, vice president of marketing for Boeing's commercial division.
Such planes are popular with budget airlines that comprise a key market for both aircraft manufacturers.
Boeing also officially announced the even stretchier 737 MAX 10X this week (see the below charts for comparisons of the different models).
Next up for type certification is the 737 Max 9, the first airplane of which rolled out of Boeing's Renton, Wash., factory on Tuesday.
"It is very hard to pick a victor out of those five shells, but there is no doubt they will cannibalise each other", said Aengus Kelly, chief executive of AerCap, the world's second-largest lessor of 737 MAX jetliners.
The 737 MAX 8 reduces fuel use and Carbon dioxide emissions by an additional 14 percent over today's most fuel-efficient single-aisle airplanes.
The MAX 9 has room for 16 to 20 more seats than the MAX 8 - boosting capacity to somewhere between 178 and 220 passengers, depending on configuration.
Meanwhile the A321 NEO was certified to take its second engine option made by the Franco-American CFM consortium last week, and continues to eat the Boeing alternative designs alive when it comes to winning orders.
The 737 MAX family is the fastest-selling commercial-aircraft family in Boeing history, accumulating orders for more than 3,600 aircraft to date from 83 customers.