GE Propulsion Test Platform
I saw this plane when I was out walking one day, near the northern tip of the Big Island. It was flying quite low, unusually so for a big plane, as it headed south toward Kailua Kona.
The plane is a Boeing 747-400, formerly owned by Japan Airlines, but now used by GE to test jet engines. Apparently, it was operating out of Kona Airport for a week, performing warm weather engine tests.