NTSB via ReutersEvidence from the door that blew off an Alaska Airlines plane is bolstering a theory that the emergency occurred because bolts required to secure the door were missing when the aircraft left Boeing’s factory, according to The Wall Street Journal. The so-called door plug on the 737 Max 9 aircraft blew out at around 16,000 feet during the flight on Jan. 5 and was later discovered in a teacher’s backyard. Now Boeing and other industry officials “increasingly believe” that the aircra