SEATTLE, WA - MAY 31: The tails of Boeing 737 MAX airplanes are seen as they sit parked at a Boeing facility adjacent to King County International Airport, known as Boeing Field, on May 31, 2019 in Seattle, Washington. Boeing 737 MAX airplanes have been grounded following two fatal crashes in which 346 passengers and crew were killed in October 2018 and March 2019. (Photo by David Ryder/Getty Images)