Okay Airways (BK)'s first Boeing 737-900ER aircraft has completed its first C1 flight in Seattle, Washington airfield, Boeing said on its official Sina Weibo account

On Tuesday morning, the new aircraft flew the Seattle skies in preparation for its handover to Okay Airways, expected in late January.

Okay Airways is the first Chinese airline to operate the 737-900ER aircraft. Eight of the advanced versions of the original Boeing 737-900 are on order after the airline converted another five 737-800s from a previous order into 737-900ERs in July 2014.

Boeing said the 737-900ER will offer more space, light, go further and offer greater fuel efficiency, compared with the 737-900.

The C1 flight, corresponding to B1 flight, was conducted by customer's test pilots who put the aircraft through its paces to verify performance. Functionality of the cabin was also assessed during the flight. The C1 and B1 flights were part of a series of work that Boeing performs before handing over the airplane to the airline.

According to a source familiar with the matter, the new plane would first be launched on Tianjin-Ningbo-Xiamen-Sanya route, after pilot training.