Erik Nelson(R), vice president of Boeing 737 Field Operations and Delivery and Wang Shusheng(C), president of Okay Airways cut the ribbon at a ceremony at Seattle in the state of Washington, the United States, March 24, 2018. China's air carrier Okay Airways witnessed Saturday the 9999th Boeing 737-800 aircraft delivered by the Boeing Company embarked on a home-bound journey back to China from the United States. (Xinhua/Wu Xiaoling)