WASHINGTON—Here are some facts about the Boeing 737-800 jet and China Eastern Airlines, involved in a crash on a domestic flight on Monday with 132 people on board. Boeing 737-800 The Boeing 737-800 is part of the 737 family, the world’s most-flown commercial aircraft series. It was developed in the 1960s to serve short- or medium-length routes. The 737-800 is part of the 737 NG or Next-Generation family—with more than 7,000 delivered since 1993—and it has a strong safety record after nearly three decades of flights. The 162- to 189-seat 737-800 was launched on Sept. 5, 1994. The NG is the predecessor to the 737 MAX. The MAX was grounded worldwide for 20 months after two fatal crashes killed 346. It remains grounded in China. The jet involved in the China Eastern accident, en route from the southwestern city of Kunming, capital of Yunnan province, to Guangzhou, capital of Guangdong …