Boeing debuted its first 737 Max 9 aircraft, the second variant in its 737 Max series, behind the Max 8. After the rollout of the Max 9 in Renton, Wash., it underwent system checks and fueling and engine runs on the flight time. The plane is expected to fly commercially sometime next year.

The aircraft boasts a maximum capacity of 220 passengers, 16 more than its precursor, and has a non-stop operation range of 3,515 nautical miles, opening up the possibility of new destinations in the single-aisle market.

“The 737 Max team continues to do a fantastic job getting us to these important milestones right on schedule,” said Keith Leverkuhn, vice president and general manager, Boeing’s 737 program. “Our primary focus is delivering an aircraft that has the legendary reliability our 737 customers depend on, plus the optimized flexibility and range capability they desire.”

The Max 8, another plane in the series unveiled in 2015, is expected to deliver to launch customer Norwegian Air Shuttle in May. Southwest Airlines, which placed a launch order for the 737 Max, expects its first aircraft in service Oct. 1.

The 737 Max is the fastest-selling aircraft in Boeing history, accumulating more than 3,600 orders from 83 customers worldwide.