Boeing rolled out its new 737 MAX 9 in Renton, Wash., on March 7. The 737 MAX 9 is a narrow-body jetliner, with a seating capacity of 220 and a range of 3,515 nautical miles.

Boeing 737 Max 9 rollout.The 737 MAX 9 is the second member of the 737 MAX family. The 737 MAX 8 is expected to be delivered to customers in the second quarter of 2017. The 737 MAX 9 is scheduled to enter service in 2018.

The 737 MAX 9 is nine feet longer than the MAX 8. Boeing also has plans for a 737 MAX 7, a smaller jet scheduled for 2019. It also plans a high density version of the 737 MAX 8, dubbed the 737 MAX 200. It will be capable of carrying 200 passengers in a single-class, high-density seating configuration.

The 737 MAX 9 was expected to begin flight testing in the coming weeks, after a series of system checks, and fueling and engine runs on the flight line.

Boeing says the 737 MAX family is the fastest-selling line of planes in its history, with more than 3,600 units ordered from over 83 countries to date.