The great-grandson of Standard Oil co-founder John D Rockefeller has been killed in a small plane crash outside New York City, a family spokesman said.
The single-engine plane took off from Westchester County Airport just after 8am local time and narrowly missed a house west of the airfield before hitting some trees, officials said.
Richard Rockefeller, of Falmouth, Maine, was the only person on board the Portland, Maine-registered aircraft.
The 65-year-old was a doctor and father of two, family spokesman Fraser Seitel said. He had recently been working on a way to treat post-traumatic stress disorder in wounded war veterans.
"It's a terrible tragedy," Mr Seitel said. "Richard was a wonderful cherished son, brother, father and grandfather."
Mr Rockefeller was the son of David Rockefeller, the former chairman and chief executive of Chase Manhattan Bank, now JPMorgan Chase, and a prominent philanthropist, and a nephew of former Vice President Nelson A Rockefeller, who also was governor of New York from 1959 to 1973.
Yesterday, Richard Rockefeller ate dinner with his father in Westchester to celebrate the family patriarch's 99th birthday, Mr Seitel said.
Mr Seitel described him as an experienced pilot whose death had left the family in shock.
The plane, a Piper Meridian, crashed in the hamlet of Purchase, a New York City dormitory community of about 10,000 residents which houses a State University of New York campus.
The airport was closed for a short time after the crash. The Federal Aviation Administration was investigating, and the National Transportation Safety Board was expected to arrive later.
An FAA control tower notified that the aircraft was missing from their radar and an emergency response was initiated.
At the time of the crash, the weather was foggy and visibility was about a quarter of a mile (400m), police and airport officials said at a news conference. Pilots of private planes make the decision about whether to fly in such conditions, officials said.
After narrowly missing the house, the plane hit some pine trees and crashed in a yard. The aircraft broke up into many pieces, which were strewn about the property, with some parts lodged in the trees.
Officials said there was no indication of a mayday or problem.
Mr Rockefeller chaired the United States Advisory Board for Doctors Without Borders for more than 20 years, ending in 2010. He was involved in numerous other nonprofit activities.
"Every aspect of his life was to advance the well-being of the world," said Tim Glidden, president of Maine Coast Heritage Trust, where Mr Rockefeller served as board chairman from 2000 to 2006.
Mr Rockefeller is survived by his wife, Nancy, and their children, Clayton and Rebecca.