By The Associated Press
An emergency landing by an Alaska Airlines jetliner last Friday prompted U.S. authorities to ground most of Boeing’s 737 Max 9 aircraft, another black mark in the troubled history of the company’s Max jets. U.S. aviation authorities have begun investigating how the paneled-over exit door —called a door plug — blew off the passenger jet shortly after takeoff. While Boeing’s Max aircraft have been plagued with problems, no previous incidents involved blowouts such as this one. Aviation experts say such blowouts are exceedingly rare in air travel.