Littlejohn said the Coast Guard in Portsmouth was notified about 2:40 p.m. that the single-engine Cirrus failed to land in Manassas, Virginia, and continued into restricted air space in Washington, D.C.
Two Air Force F16 jets confirmed the pilot was unconscious and stayed with the plane until it eventually ran out of fuel and crashed.
National Transportation Safety Board spokesman Peter Knudson said the plane was heading from Waukesha, Wisconsin, to Manassas.
Littlejohn said no one else was aboard the plane.
A Coast Guard helicopter found no sign of the plane before heading back for refueling. A C130 airplane based out of Elizabeth City, North Carolina, and an 87-foot cutter from Virginia Beach also were responding, Littlejohn said.
The plane was registered to Ronald Hutchinson, of Brookfield, Wisconsin. Relatives reached at a phone listing for him didn't want to comment Saturday night.
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