Southwest Airlines Flight 812, from Phoenix-Sky Harbor International Airport, AZ (PHX) to Sacramento International Airport, CA (SMF), diverted to Yuma International Airport, AZ (YUM) after experiencing a rapid depressurization at approximately 34,000 feet. Upon landing, a 5-foot x 1-foot hole in the crown area was observed on the left side of the airplane, aft of the over-wing exit at the stringer 4L lap joint. Of the 117 passengers and 5 crew members onboard, one flight attendant received a minor injury. Flightaware data indicate the flight was climbing through about FL344 at 15:57 when the incident happened. It landed at Yuma 16:23. PROBABLE CAUSE: “The National Transportation Safety Board determines that the probable cause of this accident was the improper installation of the fuselage crown skin panel at the S-4L lap joint during the manufacturing process, which resulted in multiple site damage fatigue cracking and eventual failure of the lower skin panel. Contributing to the injuries was flight attendant A’s incorrect assessment of his time of useful consciousness, which led to his failure to follow procedures requiring immediate donning of an oxygen mask when cabin pressure is lost.”