Northwest Orient Airlines Flight 421

Northwest Orient Airlines Flight 421 was a domestic scheduled passenger flight from Chicago, Illinois, to Minneapolis, Minnesota, United States, that crashed on 29 August 1948. The Martin 2-0-2 aircraft, operated by Northwest Orient Airlines, suffered structural failure in its left wing and crashed approximately 4.1 mi northwest of Winona, Minnesota, about 95 mi southeast of Minneapolis. A Civil Aeronautics Board investigation determined that the crash was caused by fatigue cracks in the wings of the aircraft, and recommended lower speeds and frequent inspections of all Martin 2-0-2 aircraft. All 33 passengers and 4 crew members on board were killed. The crash was the first loss of a Martin 2-0-2, and remains the worst accident involving a Martin 2-0-2, as well as the worst aviation accident in Wisconsin.

Flight

Flight 421 was served by a Martin 2-0-2 aircraft operated by Northwest Orient Airlines. It was just under a year old, and had accumulated a total airtime of 1,321 hours since it was delivered in 1947. The flight was piloted by Captain Robert Leslie Johnson, who had 5,502 hours of flying time. The copilot was David Franklin Brenner, with 2,380 hours of flight time. The stewardess onboard was Mary E. Ungs.

The aircraft departed Midway Airport at 3:50 pm, CST, carrying 33 passengers, 4 crew members, 800 USgal of fuel, and 1038 lb of baggage. Weather reports received prior to departure indicated relatively clear conditions with a few scattered rain showers en route in the vicinity of La Crosse, Wisconsin and Rochester, Minnesota. The flight progressed normally as the aircraft reached its planned altitude of 8000 ft and made its way across Wisconsin. At 4:55 pm, the aircraft reported its position over La Crosse, Wisconsin, about 125 mi southeast of Minneapolis. The aircraft received permission to begin its descent, and descended to 7000 ft at 4:59 pm.

Crash

The last communication made with the flight was a 4:59 pm report from the pilot that the aircraft had passed the 7000 ft altitude level. The pilot sounded calm, and made no indication that the aircraft was experiencing any mechanical trouble.

Between 4:45 and 5:00 pm, a number of people in the area of Winona, Minnesota, were observing a thunderstorm approaching from the northwest. These people told the Civil Aeronautics Board that the storm was increasing in intensity, and they observed increasing amounts of thunder and lightning. The aircraft continued on course in the direction of Winona, where it encountered the thunderstorm. The aircraft was seen flying below the clouds before entering the roll cloud, or leading edge of the thunderstorm. This was the last reported sighting of the aircraft; seconds later, local observers saw pieces of the aircraft falling from the sky.

Off-duty Northwest Orient Airlines pilot Captain Jack Volkel, living in Winona and who observed the crash, told newspapers that he believed that the airliner had been struck by lightning. Some local farmers said that the plane seemed to barrel roll, but also observed that while rainfall was significant, winds were relatively light.

In its August 30, 1948, edition, The New York Times reported: