During the 1990s, a series of rudder issues on Boeing 737 aircraft resulted in multiple incidents. In two separate accidents, pilots lost control of their Boeing 737 aircraft due to a sudden and unexpected movement of the rudder, and the resulting crashes killed everyone aboard. A total of 157 people aboard the two aircraft were killed. Similar rudder issues led to a temporary loss of control on at least one other Boeing 737 flight before the problem was ultimately identified. The National Transportation Safety Board determined that the accidents and incidents were the result of a design flaw that could result in an uncommanded movement of the aircraft's rudder. The issues were resolved after the NTSB identified the cause of the rudder malfunction and the Federal Aviation Administration or