The Experimental Aircraft Association told the newspaper that both planes were flying as part of an event called the Young Eagles rally.
"Our thoughts and prayers go out to the families of the pilot and passenger involved in the mishap," the association said in a release.
Dick Knapinski, a spokesman for the Oshkosh, Wisconsin-based group, said the Young Eagles rallies are intended to introduce young people to aviation.
Knapinski said the association has flown nearly 1.9 million kids since 1992. This is the first fatal accident involving the Young Eagles program since 2006 in Washington state, he said.
The National Transportation Safety Board will investigate the collision.
- AP