Northwest Airlines Flight 421 was a domestic scheduled passenger flight from

Chicago, Illinois (''City in a Garden''); I Will , image_map = , map_caption = Interactive Map of Chicago , coordinates = , coordinates_footnotes = , subdivision_type = Country , subdivision_name ...

Minneapolis, Minnesota Minneapolis () is the largest city in Minnesota, United States, and the county seat of Hennepin County. The city is abundant in water, with thirteen lakes, wetlands, the Mississippi River, creeks and waterfalls. Minneapolis has its origins ...

that crashed on 29 August 1948. The

Martin 2-0-2 The Martin 2-0-2 was an airliner introduced in 1947. The twin piston-engined fixed-wing aircraft was designed and built by the Glenn L. Martin Company. Design and development Glenn L. Martin, president of the company, intended that the Mode ...

aircraft, operated by

Northwest Airlines Northwest Airlines Corp. (NWA) was a major American airline founded in 1926 and absorbed into Delta Air Lines, Inc. by a merger. The merger, approved on October 29, 2008, made Delta the largest airline in the world until the American Airlines ...

, suffered

structural failure Structural integrity and failure is an aspect of engineering that deals with the ability of a structure to support a designed structural load (weight, force, etc.) without breaking and includes the study of past structural failures in order to ...

in its left wing and crashed approximately northwest of

Winona, Minnesota Winona is a city in and the county seat of Winona County, in the state of Minnesota. Located in bluff country on the Mississippi River, its most noticeable physical landmark is Sugar Loaf. The city is named after legendary figure Winona, who ...

, about southeast of Minneapolis. A

Civil Aeronautics Board The Civil Aeronautics Board (CAB) was an agency of the federal government of the United States, formed in 1938 and abolished in 1985, that regulated aviation services including scheduled passenger airline serviceStringer, David H."Non-Skeds: Th ...

investigation determined that the crash was caused by

fatigue Fatigue describes a state of tiredness that does not resolve with rest or sleep. In general usage, fatigue is synonymous with extreme tiredness or exhaustion that normally follows prolonged physical or mental activity. When it does not resolve ...

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 four crewmembers 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.

Flight

Flight 421 was served by a Martin 2-0-2 aircraft was operated by Northwest Airlines. It was just under a year old, and had accumulated a total airtime of 1321 hours starting in 1947. The flight was piloted by Captain Robert L. Johnson, 30, who had 5,502 hours of flying time. The copilot was David F. Brenner, 27, with 2,380 hours of flight time. The aircraft departed Chicago at 3:50 pm, CST, carrying 33 passengers, four crewmembers, of fuel, and 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 La Crosse is a city in the U.S. state of Wisconsin and the county seat of La Crosse County. Positioned alongside the Mississippi River, La Crosse is the largest city on Wisconsin's western border. La Crosse's population as of the 2020 census w ...

and

Rochester, Minnesota Rochester is a city in the U.S. state of Minnesota and the county seat of Olmsted County. Located on rolling bluffs on the Zumbro River's south fork in Southeast Minnesota, the city is the home and birthplace of the renowned Mayo Clinic. Acco ...

. The flight progressed normally as the aircraft reached its planned altitude of and made its way across Wisconsin. At 4:55 pm, the aircraft reported its position over La Crosse, Wisconsin, about southeast of Minneapolis. The aircraft received permission to begin its descent, and descended to 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 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

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 An arcus cloud is a low, horizontal cloud formation, usually appearing as an accessory cloud to a cumulonimbus. Roll clouds and shelf clouds are the two main types of arcus clouds. They most frequently form along the leading edge or gust fronts o ...

, 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. An off-duty Northwest Airlines pilot 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 A barrel roll is an aerial maneuver in which an airplane makes a complete rotation on both its longitudinal and lateral axes, causing it to follow a helical path, approximately maintaining its original direction. It is sometimes described as a ...

, but also observed that while rainfall was significant, winds were relatively light.
plaintext
In its Aug. 30, 1948, edition, ''The New York Times'' reported:

Investigation and follow-up

The aircraft crashed on a forested bluff on the Wisconsin side of the

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it f ...

, between Winona and

Fountain City, Wisconsin Fountain City is a small city bordering the Mississippi River in Buffalo County, Wisconsin, United States. The population was 859 at the 2010 census. History Fountain City was originally called Holmes' Landing, after Thomas Holmes, who settled ...

. The aircraft was torn into four large pieces, with numerous deposits of smaller wreckage. The large sections were located in a straight line with a bearing of 335°, approximating the intended flight path. These large sections were the

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

tail assembly The empennage ( or ), also known as the tail or tail assembly, is a structure at the rear of an aircraft that provides stability during flight, in a way similar to the feathers on an arrow.Crane, Dale: ''Dictionary of Aeronautical Terms, third e ...

, outer left wing, and the inner left wing. The mangled bodies of all 37 deceased were located within the wrecked fuselage that had rolled into a deep ravine. The sides of the ravine were so steep, rescuers formed a human chain to carry the passengers' remains up the rocky crevice.
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Horse-drawn farm wagons loaded with human remains made their perilous way down the bluff. Contemporary news reports estimated that as many as 20,000 people came to see the crash scene and render aid.

investigators concluded that the outer portion of the wing had detached from the rest of the wing. The investigation revealed a

crack 7/8 inch long and 3/32 inch deep at the point of detachment. Similar cracks were found on the wing root fittings of another Martin 2-0-2 aircraft that flew the same flight path through the same storm shortly after Flight 421. October inspections of three other Martin 2-0-2 aircraft revealed identical fatigue cracks in similar locations. The CAB report concluded: The investigation determined that a

spar SPAR, originally DESPAR, styled as DE SPAR, is a Dutch multinational that provides branding, supplies and support services for independently owned and operated food retail stores. It was founded in the Netherlands in 1932, by Adriaan van Well, ...

on the front left of the wing separated, quickly followed by the lower rear spar and the connections which attached the outer wing to the center section. The loss of the left wing caused the aircraft to roll left, whereupon the

and the right horizontal stabilizer collided with the separated wing. The initial separation was caused either by a wind gust in excess of operating velocity, or a similar lower-velocity gust after the material had become fatigued. The Board also recommended frequent inspections of wing root fittings for the development of fatigue cracks, increasing the thickness of the portion of the wing attached to the fuselage, and reduction of operating speeds by 10%.

. Docket #SA-178. File #1-0117. June 29, 1949
profilepdf

US Department of Transportation The United States Department of Transportation (USDOT or DOT) is one of the executive departments of the U.S. federal government. It is headed by the secretary of transportation, who reports directly to the President of the United States and ...

. Accessed online from a previous URL on September 7, 2009. In April 1949, Northwest Airlines sued the

Glenn L. Martin Company The Glenn L. Martin Company—also known as The Martin Company from 1957-1961—was an American aircraft and aerospace manufacturing company founded by aviation pioneer Glenn L. Martin, and operated between 1917-1961. The Martin Company produc ...

, manufacturers of the Martin 2-0-2, for $725,000. The lawsuit claimed that the company had sold the airline five defective aircraft, including the aircraft lost in Flight 421. Glenn Martin, president of the aircraft manufacturing corporation, dismissed the lawsuit as a mere formality, a bit of meaningless legal maneuvering to appease disagreeing insurance companies. Flight 421 was the first hull loss of a Martin 2-0-2. It remains the deadliest accident involving the 2-0-2. It was Northwest Airlines's worst air disaster at the time, and the first accident in over a billion miles of flight.

References

External links

Report
from the

PDF
- ''edcoatescollection.com'' {{DEFAULTSORT:Northwest Airlines Flight 0421 Aviation accidents and incidents in the United States in 1948 Airliner accidents and incidents in Wisconsin Airliner accidents and incidents caused by design or manufacturing errors Buffalo County, Wisconsin Disasters in Wisconsin

421 __NOTOC__ Year 421 ( CDXXI) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Agricola and Eustathius (or, less frequently, year 117 ...

Accidents and incidents involving the Martin 2-0-2 1948 in Wisconsin August 1948 events in the United States

Flight

Crash

Investigation and follow-up

See also

References

External links