The aircraft was reported to have taken off from Essex Airport, New Jersey, with Mr Kennedy at the controls. Also aboard were his wife, Carolyn Bessette, and her sister Lauren. He had recently broken an ankle in a gliding accident and there was speculation that his injury might have interfered with his manipulation of the plane's controls.
The last contact with the plane, a Piper Saratoga, was reported as it was on the final approach to Martha's Vineyard, off the Massachusetts coast. Yesterday, debris, including a suitcase with a tag bearing the name of Lauren Bessette, was found 100 yards off the island as an intensive air and sea search, involving both Coast Guard and US military aircraft and ships, continued across a swathe of ocean along the flight path.
Erin McCarthy, a witness, said she saw a black bag in the water with Lauren Bessette's business card attached to it. A wheel, a strut, and other wreckage possibly from the plane were also reported to have been washed up. No flight plan had been filed, but there was no legal obligation to do so.
Tragedy has never been far from the Kennedys since the assassination of President Jack Kennedy in November 1963. The dynasty that was once associated with the American Camelot is now known more for loss and scandal. Eerily, this weekend is also the 30th anniversary of Senator Edward Kennedy's car crash on a bridge on the island of Chappaquiddick, near Martha's Vineyard, that killed Mary Jo Kopechne.
Senator Kennedy was among family members who had gathered at the Hyannisport compound for what was meant to be a weekend of joy - the marriage of Rory Kennedy, whose father, Robert Kennedy, was also slain by an assassin's bullet in 1968. (Her mother, Ethel, was pregnant with her at the time.) In 1997, Rory lost her brother, Michael Kennedy, when he died in a skiing accident in Aspen.
John Kennedy jr and his wife were due to join the family in Hyannisport but, by yesterday morning, plans for the wedding had been scrapped. The family was instead gathered for a Mass to pray for "the safety of the loved ones, as well as for Rory," according to a family spokesman. Neighbours from Cape Cod were also gathering outside the compound for news.
The Kennedys may have been landing at Martha's Vineyard only to drop off Lauren Bessette, before continuing on to Hyannisport. Flying conditions at the time were described as normal, but very hot temperatures on Friday had led to thick haze that may have severely impeded visibility.
JFK jr, who four years ago founded a political monthly, George, had apparently only abandoned his crutches last Thursday. The previous night he had dinner in New York with the English art dealer, Jay Jopling, who represents Damien Hirst, and Jopling's wife, Sam Taylor-Wood. His ankle injury was so severe he could hardly walk, they said. So bad was the pain that later that evening he left a party given by the English magazine, Dazed & Confused.
Major US television networks suspended scheduled programming to focus on the search, and America once again found itself caught up in the sufferings of the closest thing it has to a royal family. In Washington, President Bill Clinton expressed his concern.