Alaska Airlines promptly grounded its entire fleet of Boeing 737-9 aircraft, and the FAA has followed suit by grounding 171 Boeing 737-9 MAX airplanes. The FAA's scrutiny extends to examining Boeing's manufacturing practices and production lines, with a specific focus on subcontractor Spirit AeroSystems. A recent update from the FAA indicates that, in addition to the grounding, airlines are now required to visually inspect the mid-exit door plugs of Boeing 737-900ER planes. Despite not being part of the MAX fleet, these aircraft share the same door plug design, prompting the FAA to ensure thorough safety checks across the broader Boeing 737 model range. FILE – The logo for Boeing appears on a screen above a trading post on the floor of the New York Stock Exchange, July 13, 2021.