The flight, which began at the 60th Street Heliport on the East River in Manhattan, was proceeding routinely until the last moments.

A half-hour before the crash, the helicopter was picked up on radar screens in the control tower at McGuire Air Force Base in Wrightstown, N.J., as it was flying over Colts Neck in central Monmouth County, 35 miles south of Manhattan. The craft remained on the McGuire screens for approximately another 35-mile leg of its flight before it was switched to the radar space of Atlantic City International Airport in Pomona, a spokesman for McGuire Air Force Base, Sgt. Milan Christi, said.

A witness camping in the pines near the crash site, Thomas Murray of East Providence, R.I., told The Associated Press that he heard a loud bang, ''like a piston rod going,'' and saw the main rotor stop spinning break off. ''It went straight down,'' he said.

Although the Trump Organization maintains a fleet of commuter helicopters for its executives, a spokeswoman for Mr. Trump, Norma Foerderer, said the craft, an eight-seat Agusta 109A, had been leased from Paramount. She said she was uncertain whether the lease only covered the flight yesterday or was long-term.

Mr. Hyde, a father of seven and an accountant, joined the Trump Organization in 1986 as president and chief operating officer of Trump Plaza. He began his career in the casino industry in 1971 in Las Vegas, Nev. In the late 70's, after New Jersey had legalized casino gambling in hopes of reviving Atlantic City, he ''played an instrumental role in the operations of several casino hotels,'' according to a biography from Mr. Trump's office.

Since joining Mr. Trump, Mr. Hyde, a graduate of Weber State College, advanced to head all three casinos, the Taj Mahal, which is expected to open next year; the Plaza, and the Castle.

Mr. Etess, a graduate of Columbia University and former vice president and general manager of Grossinger's, his family's hotel and country club in the Catskills, had been president of the Plaza casino hotel and was instrumental in its becoming a forum for championship boxing matches. As the new president of the Taj Mahal, Mr. Etess was developing marketing programs to develop the casino as a gambling, entertainment and convention center, Mr. Trump's office said.

Mr. Benanav, a graduate of Cornell University, was general manager of the Phildelphia Airport Hilton and front-office manager for Essex House in New York, before joining Mr. Trump's casino staff in 1986 and playing an instrumental role in a $100 million renovation of the Trump Plaza.