The National Transportation Safety Board chairwoman says heroic actions by the crew aboard an Alaska Airlines flight ensured everyone survived last year when the door plug panel blew out of the plane.

While it feels like Boeing has been the subject of an endless stream of worrying quality control discoveries, it's been 18 months since a door plug blew out on a Boeing 737 Max at 14,830 feet over Portland,

The nation's top safety investigators concluded there were multiple systemic failures that led to a midair blowout during the flight of an Alaska Airlines Boeing 737 Max jet last year.