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Last updated: 29 November 2020
Status:Final
Date:Thursday 29 June 1972
Time:10:37
Type:Silhouette image of generic DHC6 model; specific model in this crash may look slightly different
de Havilland Canada DHC-6 Twin Otter 100
Operator:Air Wisconsin
Registration: N4043B
C/n / msn: 13
First flight: 1966
Total airframe hrs:15664
Engines: 2 Pratt & Whitney Canada PT6A-20
Crew:Fatalities: 2 / Occupants: 2
Passengers:Fatalities: 6 / Occupants: 6
Total:Fatalities: 8 / Occupants: 8
Collision casualties:Fatalities: 5
Aircraft damage: Damaged beyond repair
Location:ca. 8 km S of Appleton, WI (   United States of America)
Phase: Approach (APR)
Nature:Domestic Scheduled Passenger
Departure airport:Sheboygan Memorial Airport, WI (SBM/KSBM), United States of America
Destination airport:Appleton-Outagamie County Airport, WI (ATW/KATW), United States of America
Flightnumber: 671
Narrative:
North Central Flight 290, a Convair CV-580 departed Green Bay (GRB) at 10:30 for a flight to Oshkosh (OSH), Milwaukee (MKE) and Chicago. The aircraft climbed to 2,500 feet and proceeded on an approximate course to Oshkosh. At 10:35 the flight made its initial contact with Oshkosh tower stating, "...we're about, seven northeast, two thousand five hundred, VFR." The crew were cleared for a runway 27 landing at 10:36. At that same time, an Air Wisconsin Twin Otter turboprop plane was on its way from Sheboygan (SBM) to Appleton (ATW) at the same altitude. An in-flight collision occurred at 10:36:47 over Lake Winnebago, at an altitude of approximately 2,500 feet. Explosion and fire followed the and both aircraft fell into Lake Winnebago. The accident occurred in hazy sunlight below a scattered cloud layer.

Probable Cause:

PROBABLE CAUSE: "The failure of both flight crews to detect visually the other aircraft in sufficient time to initiate evasive action. the Board is unable to determine why each crew failed to see and avoid the other aircraft; however, the Board believes that the ability of both crews to detect the other aircraft in time to avoid a collision was reduced because of the atmospheric conditions and human visual limitations."

Accident investigation:
cover
Investigating agency: NTSB
Status: Investigation completed
Duration: 300 days (10 months)
Accident number: NTSB/AAR-73-09
Download report: Final report

Classification:
Mid air collision
Loss of control

Sources:
» NTSB-AAR-73-9


Photos

photo of -
 

Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Sheboygan Memorial Airport, WI to Appleton-Outagamie County Airport, WI as the crow flies is 76 km (47 miles).
Accident location: Approximate; accuracy within a few kilometers.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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