"For much of Jeff Immelt’s 16-year run atop one of the world’s largest conglomerates, an empty business jet followed his GE-owned plane on some trips to destinations around the world"

WSJ:

The two jets sometimes parked far apart so they wouldn’t attract attention, and flight crews were told to not openly discuss the empty plane, the people said.

The second plane was a spare in case Mr. Immelt’s jet had mechanical problems.