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Casualties unknown

Aircraft Sustains Substantial Damage After Encountering Severe Turbulence in IMC (N1553N)

Janesville, WI, US

On August 19, 1994, a Beech C90A (registration N1553N) operated by University OF North Dakota was involved in an aviation accident near Janesville, WI. Investigators recorded the probable cause as: the pilot-in-command's exceeding the design structural limits of the airplane. Factors were turbulence in clouds and the pilot- in-command;s continued flight into known adverse weather. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 8 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-19Data APIEditorial standards

During cruise flight at 20,000 feet, the aircraft entered instrument meteorological conditions while maneuvering around thunderstorms. It encountered severe turbulence that rendered flight instruments unreliable before positive control was regained.

What happened

The flight was operating in cruise conditions at an altitude of 20,000 feet mean sea level (MSL). While navigating around convective build-ups, the aircraft inadvertently entered instrument meteorological conditions (IMC). Shortly after penetration into the cloud layer, the airplane encountered severe turbulence. This event caused several flight instruments to become unreliable, with indications that they had tumbled or failed.

Positive control of the aircraft was eventually regained at an altitude between 16,800 and 17,000 feet MSL. Following the incident, a physical examination of the airplane revealed substantial damage to the airframe.

Weather

Related events

Same operator

Frequently asked questions

What happened in the 19 Aug 1994 Beech C90A accident near Janesville, WI?

During cruise flight at 20,000 feet, the aircraft entered instrument meteorological conditions while maneuvering around thunderstorms. It encountered severe turbulence that rendered flight instruments unreliable before positive control was regained.

What aircraft was involved and where did it happen?

The accident on 19 Aug 1994 involved a Beech C90A, registration N1553N, operated by University OF North Dakota, at Janesville, WI.

What was the probable cause of the accident?

the pilot-in-command's exceeding the design structural limits of the airplane. Factors were turbulence in clouds and the pilot- in-command;s continued flight into known adverse weather.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001206X02002. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.