The Oregonian reports that Steve Sliwa expanded the company to more than 700 workers, reaching $128 million in annual sales in 2008, when Boeing acquired it as a subsidiary.
Company spokeswoman Jill Vacek says Insitu plans to hire a replacement soon.
The company was founded in 1994. It has developed and produced aircraft such as the ScanEagle, a 40-pound aircraft used for surveillance, search and rescue, mapping, mineral exploration and research.
Insitu has said it's looking for a Columbia Gorge site to consolidate some of its 20-plus Gorge-area locations into a single corporate campus.