The discovery of airplane parts and other evidence at South Beach this week confirms that two men traveling in a private plane that disappeared 10 days ago were killed in a catastrophic crash in Vineyard waters.

Pilot Richard A. Colson, 43, of Edgartown, and his friend, Robert B. Buchanan, 45, of Tisbury, were flying into Martha's Vineyard Airport during heavy rains on Nov. 12 when their plane dropped from radar. The disappearance prompted an all-night search on land and water by more than 150 people. The U.S. Coast Guard and local authorities continued the search without result through last week.

Last Friday, part of Mr. Colson's 1998 Mooney Ovation2 plane was discovered at South Beach in an area off Long Point in West Tisbury. According to Martha's Vineyard Airport manager Bill Weibrecht, the serial number on the part corresponds with FAA records for the missing plane.

"An interior cabin floor piece washed up on South Beach near Scrubby Neck," said state environmental police Sgt. William L. Searle. "That was enough for us to start the search back up again, but only in the area of the beach."

The sergeant said the search was restricted to South Beach as of Friday afternoon.

Despite foul weather, a passerby on the beach found more evidence of the crash on Saturday. An antenna, attached to a piece of the aluminum skin of the plane measuring two feet by four or five inches, was found near Tisbury Great Pond on South Beach.

All evidence suggests that the plane hit the sea at great speed and broke apart on impact. The sergeant said the quality of the material that has washed ashore confirms the severe nature of the crash and death of the pilot and passenger.

"We will probably be able to determine what happened," he said. "The damage done to the parts I have seen would indicate that the end of the plane was catastrophic."

In its search of area waters, the U.S. Coast Guard used three helicopters, two search boats and a cutter, but suspended its efforts after about a day. But for the last two days, a team of Vineyarders conducted its own search for the craft using underwater side scan sonar.

The privately funded search team consists of H. Arnold Carr, president of American Underwater Search and Survey of Cataumet, and his assistant, Story Fish. They and their computer-driven equipment were taken out in a 35-foot private boat belonging to Dale McClure of Vineyard Haven.

Mr. McClure owns and operates Marion M., a 35-foot fiberglass Duffy; the 400-horsepower diesel-powered boat has been in searches before. On board were three members of the Oak Bluffs dive team.

"They are doing this on their own," said Sergeant Searle. "It is not formally part of any state or federal effort .... I have great respect for them, for essentially they are doing the search on their own, like we did on the shore."

Mr. Carr is among the world's top underwater search experts. He grew up on the Island and for many years worked for the state Division of Marine Fisheries. On the side, he managed his company that has looked for and found lost airplanes and vessels all around the world. Story Fish is the brother of Mr. Carr's partner, John Fish.

In November 1993, Mr. Carr, Mr. McClure and others undertook a similar search off Nantucket to help friends and family members of those lost on the recreational fishing boat Tyree. Earlier that fall, the Tyree had sunk south of Nantucket with four Vineyarders aboard. The bodies of three were recovered soon after the sinking on Oct. 9, 1993; the fourth person was never found.

Yesterday, sea conditions hampered efforts by the Marion M. to make a day-long search. On board were Oak Bluffs fire department divers: assistant fire chief Peter Forend, lieutenant Paul Humber and firefighter Todd deBettencourt. Diver Tony White of the same team was aboard on Wednesday.

On board the Marion M. yesterday, Will Lewis of Edgartown told the Gazette that they had leads, but no success as yet. Mr. Lewis said he was a friend of Richard Colson..

On Monday the family and friends of Mr. Buchanan held a memorial service at Our Lady Star of the Sea church in Oak Bluffs. The service was officiated by Father Michael Nagle. His mother, Jody Buchanan of Estero Beach, Fla., told the Gazette that among those attending the service were her son Daniel, 40, of Bonita Springs, Fla. Others came from as far away as Colorado.

She said a number of those at the service had spent part of their visit here walking the beaches of the Island in an effort to help.

State police Sgt. Neal Maciel said the state police are the information clearinghouse for state and federal agencies: "We're collecting any material that is turned in [and] are holding onto the material until the proper investigating team takes over." The National Transportation Safety Board and Massachusetts Aeronautics Commission will pick up the investigation at some point, he added.

Investigators already know that on Nov. 12, Mr. Colson made at least one failed approach to runway six before 8 p.m. during a heavy downpour. He swung the plane to the right to make a second approach and dropped from radar.

"It is never completely closed until we get the wreckage," Mr. Weibrecht said.

Mr. Colson was a building contractor who was the principal of Vineyard Builders Association, and was also a Dukes County airport commissioner. Mr. Buchanan was a skilled woodworker, known best for his cabinet work.

Sergeant Searle said an ongoing search effort involved between 20 and 25 people.

"If anyone finds anything, they should turn it over to the Edgartown police or the Massachusetts State Police in Oak Bluffs. Please pay attention where you found it, for this will help in the search for the plane," Sergeant Searle said.

"We still have to find the plane to bring closure to this for the families," he said.

The regular mass on Monday at St. Elizabeth's Church in Edgartown will be held for Mr. Colson. A memorial service for Mr. Colson will be held at 1 p.m. on Friday, Nov. 29, at the Grange Hall in West Tisbury. The family has asked that any memorial gifts be made to the MV Harley Riders to benefit both families and to support the recovery effort.

A Robert B. Buchanan memorial fund has been established at the Martha's Vineyard Cooperative Bank, P.O. Box 668, Vineyard Haven, MA 02568.