DES MOINES, Iowa -- Federal aviation officials said that a cabin door opened on a single-engine airplane owned by the University of Dubuque before it crashed in Cassville, Wis.

Aviation students Grant Vogt, of Dubuque, and Cory Alsip, of Glendale Heights, Ill., were injured in the crash on Sept. 3, 2008. Vogt died six days later.

They were flying from Dubuque to Prairie Du Chien, Wis., when they diverted to Cassville and crashed at Eagle's Roost Resort.

In a report released last week, the National Transportation Safety Board said the left seat pilot reported the right cabin door opened in flight. The right seat pilot tried to hold the door closed as the flight diverted to Cassville, but it opened again and the plane crashed.

The village of Cassville is about 100 miles from Madison near the Iowa border.