Overview
On 29 August 1948, Northwest Orient Airlines Flight 421, a Martin 2-0-2 aircraft, was operating a scheduled domestic passenger flight from Chicago, Illinois, to Minneapolis, Minnesota. During the flight, the left wing suffered a structural failure, causing the aircraft to crash approximately 4.1 miles northwest of Winona, Minnesota, about 95 miles southeast of Minneapolis. The crash resulted in the deaths of all 33 passengers and 4 crew members on board.
Investigation
The Civil Aeronautics Board (CAB) investigated the accident and determined that fatigue cracks in the wings were the cause of the structural failure. In response, the CAB recommended that all Martin 2-0-2 aircraft be operated at reduced speeds and undergo frequent inspections to detect any fatigue cracks.
Significance
This accident was the first loss of a Martin 2-0-2 aircraft. It remains the deadliest accident involving the Martin 2-0-2 and is also the worst aviation accident in Wisconsin.