July 13, Minden, Nev. / Schempp-Hirth Nimbus 4DM

At 13:10 PDT, a Schempp-Hirth Nimbus 4DM motorized glider broke up in flight near Minden, killing pilot William Ivans and passenger Donald Engen, director of the National Air and Space Museum and former administrator of the FAA. Witnesses said the glider was turning tightly in a thermal when it entered a spiral. The pilot stopped the rotation but the nose dropped further. As the pilot pulled out of the dive, the wings disintegrated.