In life, flamboyant lawyer and developer Henry H. Tiffany traveled in the fast lane, with a Jaguar for the roadways, a 35-foot sailboat for jaunts to the Bahamas and a private plane for quick hops from the landing strip on his 300-acre estate in the Blue Ridge foothills. When last in the public eye outside his home turf around Waynesboro, Va., he had spent most of the last two months of 1978 in a Haitian jail before a judge acquitted him of a charge that he had smuggled nearly a ton of marijuana into the island nation.

As it turned out, the circumstances of his death a week ago yesterday equaled the panache--and some of the mystery--of his life.

Tiffany, 47, and six young people he had befriended were killed when an Air Force F-4C jet fighter clipped Tiffany's plane 9,500 feet over the Atlantic Ocean, just off the coast of North Carolina. The twin-engine Beechcraft Baron carrying Tiffany and its six other occupants plummeted through the clouds and sank 110 feet below the ocean surface. The Air Force jet, which according to officials was on a routine intercept mission to identify Tiffany's plane as it approached the U.S. mainland, returned safely to Seymour Johnson Air Force Base in Goldsboro, N.C., with its left wing damaged but its two-man crew uninjured.

Marine and Coast Guard rescue workers found only a small amount of debris from Tiffany's plane adrift in the ocean--some luggage, a portion of a life raft, seat cushions and twisted structural pieces that possibly came from the aircraft's interior. No bodies have been recovered.

The mid-air collision, believed to be the first between a private plane and an Air Force jet on an intercept mission, is now under investigation by the Air Force, the National Transportation Safety Board and the Federal Aviation Administration.

A basic issue to be addressed by the investigations is whether the coastal airlanes are safe for pilots of private planes who wander, as Tiffany did, into an Air Defense Identification Zone.

The accident raises other questions as well about Air Force procedures:

How long did it take the Air Force air controllers to inform the F-4C pilot that the FAA had made radio contact with Tiffany?

According to the Air Force, Capt. John A. Weller, the Phantom pilot, was not told that Tiffany had been identified until after the collision.

Why was an Air Force jet equipped with radar and manned by two experienced, but part-time Air National Guard flyers from Michigan, so close to Tiffany's plane?

Another key question concerns Tiffany and will probably never be answered: Why did an experienced pilot file a flight plan with the FAA as he left Nassau Jan. 9, but then fail to activate it once he was airborne?

The FAA says that when pilots activate such plans for U.S.-bound flights from the Caribbean and the Bahamas, FAA air controllers routinely notify the 20th North American Aerospace Defense Command (NORAD) so that its fighter pilots know they don't have to scramble their jets on a second's notice to take off and learn the identity of a particular airplane as it approaches the U.S.

By not activating the plan, Tiffany set in motion a critical segment of the nation's air defense system. Lt. Col. Jerry Hix, spokesman for the 20th air defense command, declined to say how close interceptor pilots normally fly to other aircraft, but said their mission is to "visually identify" unknown planes through the type of aircraft or their registration number. He said that fighter pilots in NORAD's 20th region scrambled against 166 unknown aircraft in the last year, with 111 of them being identified before they were intercepted and the other 55 visually identified in the sky.

It is likely to be weeks before crash investigators reach any conclusions about the cause of the mid-air collision. According to the Air Force, Weller, 36, and Lt. Col. Lester R. Williams, 40, the weapons system officer aboard the fighter jet, have been grounded and "reassigned to participate in the investigation."

Meanwhile, in Waynesboro and Virginia Beach, relatives of the victims have been gathering for memorial services.

Several of the parents of the crash victims declined comment on the Air Force's performance in tracking the flight of Tiffany's plane. But they voiced their esteem for Tiffany, a man several of them had never met and only knew through the laudatory comments their children had made about him.

"We did not know Mr. Tiffany," said Vonnie Schlimgen, the mother of Richard Schlimgen, a 20-year-old University of Virginia junior from Virginia Beach who was killed in the crash. "But our son felt this was one special man."

She said her son met Tiffany through a friend, Edward Furniss, 20, of Virginia Beach, another crash victim, and that they often rode Tiffany's horses at his Albemarle County estate.

Howard Whitaker, a Manhattan attorney and Furniss' stepfather, described Tiffany as "a terrific guy. He loved life--skiing, sailing, the outdoor life." He said that when Furniss' father, a close friend of Tiffany's, was killed in the 1977 crash of a commercial jetliner in Georgia, Tiffany "became a surrogate father to Edward."

Tiffany lived with his wife Patricia and the youngest of their three daughters on the rolling acreage of their closely guarded estate, called Corville Farms. Two older daughters attend college in North Carolina and Arkansas. He had a general law practice, according to his administrative assistant, Lee Berkhimer, and also was developing a Waynesboro apartment project.

Around Waynesboro, Tiffany was viewed, with his wealth, his penchant for white suits and the stern signs warning people to stop before entering his estate, as somewhat of a mysterious figure. At one time he claimed he was one of "the" Tiffanys, a relationship denied by the famed jewelry firm. His flamboyant reputation was only heightened by the 1978 arrest in Haiti.

Flying a different plane than the one that crashed, Tiffany and a passenger, Jack Melcher, also of Waynesboro, were forced down in Haiti when the aircraft developed engine trouble. Haitian police said that the day after the forced landing they found close to a ton of marijuana in neat bundles, some of it aboard the aircraft and much of it lying in the field where Tiffany had landed.

Tiffany developed a variety of infections during the nearly two months he was jailed in Haiti. After a three-day trial a judge cleared him and Melcher of the criminal charges, saying that their plane was incapable of carrying all the contraband police found.

Returning to Waynesboro, Tiffany resumed his law practice and development business.

Each Christmas, Tiffany, his family and some of their friends sailed his boat, the Mystique, from Virginia Beach, where it is docked during the summer months, to Nassau for the winter. This time, Tiffany, and apparently 11 others, set sail on Dec. 18, making it as far as Wilmington, N.C., by Dec. 23.

Among the passengers were his wife; two of their daughters; the Tiffanys' Irish housekeeper, Elis O'Mahony, 21; James Slacke, 18, of Virginia Beach, who was living with the Tiffanys on their estate; Furniss and Schlimgen.

When the dozen sailors docked in Wilmington, Tiffany flew the Virginia Beach residents back home so they could be with their families for Christmas and apparently then ferried his family back to their estate for the holiday. On Christmas night, the group reassembled on the boat and resumed the trip to the Bahamas.

Vonnie Schlimgen said the group reached Freeport by New Year's weekend. Then, according to Berkhimer, Tiffany's aide, the lawyer and his family flew back to Virginia on Jan. 3. Four of the original group, O'Mahony, Slacke, Furniss and Schlimgen, stayed in the Bahamas to sail the boat on to Nassau.

Berkhimer said that Tiffany worked at his law practice the week after New Year's and then flew back to the Bahamas in his plane on Jan. 7, after stopping in Norfolk to pick up two other young friends of the Tiffanys, Jo-Al Kohl, 23, and her roommate, Robin Graham Streib, 24, both of Virginia Beach.

At 1:49 p.m. on Jan. 9, Tiffany, the four who had spent the week in the Bahamas and the two other women who had gone there the previous weekend started their flight back to Norfolk. Tiffany, according to the FAA, radioed for weather conditions when he was about 30 miles south of Cherry Point, N.C., and an air traffic controller at Leesburg advised him that to avoid rain in the area he might want to make a westward turn toward the mainland to fly around the inclement weather.

At the same time, the controller told Tiffany that the Air Force had sent up two F-4C fighter jets to learn his identity. The FAA said its controller spotted Tiffany's plane on the radar and had informed the Air Force that it had made radio contact with him.

Suddenly, however, "we lost radio and radar contact," the FAA spokesman said.

The jet fighters would not have been able to radio Tiffany directly because they use a different radio frequency. The Air Force says that crowded radio channels make it impossible to use the same frequencies as private aircraft and since military pilots do not know what they are going to find in the air they may not want to be able to talk to another pilot.

The Air Force said that neither Weller and Williams, nor the pilot of the other intercept jet, were informed "prior to the collision that the aircraft was friendly." Safety board investigator Philip Powell said Weller and Williams told him they were in a cloud and "could not see the aircraft," but that "they knew something had happened" when they hit it.

The investigator said the leading edge and bottom side of the F-4's left wing were damaged in the collision.

The Air Force refused to make Weller and Williams available for an interview pending completion of its investigation.

Some of the relatives said it was too soon to assess blame for the accident.

Carol Adams of Virginia Beach, Robin Streib's mother, said, "I don't have any animosity toward anyone. I'm sure if they were at fault it wasn't intentional."