The deaf pilot whose single engine airplane crashed last Thursday on a runway at Katama Airfield in Edgartown remained in critical condition yesterday in the intensive care unit at Beth Israel Deaconess Medical Center in Boston.

Alec I. Naiman, a 51-year-old associate professor who teaches sign language at Nassau Community College on Long Island, N.Y., was attempting to land the 1979 Cessna Skyhawk shortly after 1 p.m. when eyewitnesses say the plane stalled and fell at least 50 feet to the ground.

Mr. Naiman and two passengers in the plane all sustained broken legs and other injuries and were initially treated by the trauma team at the Martha's Vineyard Hospital before being airlifted to the mainland.

Both passengers, who are also deaf, are now listed in good condition at Boston hospitals. They are Jeffrey Willoughby, 40, of Ofallon, Mo., and his teenage daughter, Jessica Willoughby. Miss Willoughby had spent the weekend in the intensive care unit at Children's Hospital Boston, but her condition has improved, a hospital spokeswoman said yesterday. Mr. Willoughby is being treated at Brigham and Women's Hospital.

The Skyhawk was one of 11 small planes piloted by members of the Deaf Pilots Association who took off from Plymouth Municipal Airport Thursday morning as part of a weeklong convention of deaf aviators who gather annually around the country.

The cause of the crash is still under investigation by the state police, the Massachusetts Aeronautics Commission and the Federal Aviation Administration (FAA). "We're in the very beginning stages of the investigation," said Richard Bunker, an inspector with the state aeronautics agency in Boston.

Mr. Bunker and an FAA investigator arrived on the Island by helicopter shortly after the crash. He does not expect to release any findings before December and possibly not until next year.

According to eyewitness accounts, Mr. Naiman was preparing to land the Cessna on either runway three or six, which share the same starting point, but a biplane taxiing down runway three apparently forced Mr. Naiman to abort the landing.

Mr. Naiman pulled up abruptly and attempted a go-around, but the plane stalled and then fell.

"Really what he did out there was pilot error," said Michael Creato, manager at the Katama Airfield and a co-owner of the biplane. "It shouldn't have been related to not being able to hear."

Paul Santopietro, the pilot of a charter Waco biplane which is owned by Classic Aviators, said he had already moved out of the way for two other airplanes to land while he was back-taxiing down the runway to prepare for his take-off.

"When you're on the runway, it's your runway. They shouldn't be landing if I'm on the runway," he told the Gazette last week.

But yesterday, Chris Hyldburg, the owner of a flight school in Plymouth that rented some of the airplanes to the Deaf Pilot's Association, defended Mr. Naiman's actions.

"An aircraft on final approach has priority," said Mr. Hyldburg. "And an airplane in distress has priority over any other aircraft. At a non-towered airport, there are recommended procedures but they aren't cast in stone."

The Federal Aviation Administration issues pilot certificates to deaf people but restricts them to flying only into uncontrolled or non-towered airports, or airports that do not require radio communications for landings or takeoffs. Katama is an untowered airport.

Mr. Creato had been notified that the deaf pilots were coming to Katama but not the exact day of the week.

Earlier in the week, the pilots had flown to Block Island, R.I. and to Provincetown, said Mr. Hyldburg.

After the crash, the emergency response was swift. Lifeguards at nearby South Beach who witnessed the Skyhawk crash ran to the scene.

State police Lieut. Robert Moore said the girl was in the backseat of the four-seater plane. All three victims of the crash broke both legs in addition to sustaining other bone fractures and injuries.

"There were significant injuries so we assembled the trauma team," said Dr. Timothy Tsai, the director of emergency services at the Martha's Vineyard Hospital.

Dr. Tsai credited emergency medical technicians, paramedics and the hospitals for the smooth response. The fact that the victims were deaf initially posed a difficulty.

"We started scrambling for people who could sign," he said. "A general announcement went out over the intercom. I don't know where these people all came from but these signing lay people showed up out of nowhere and were a tremendous help."

One of those people who helped interpret for the deaf victims was Oak Bluffs resident Gail Stevenson, who works as a secretary in the hospital. She had learned sign language in the seventies while a college student in Rochester, N.Y.

"I told my supervisor I knew sign language so they sent me over," she said. "When people are hurt, they're scared and have trouble communicating anyway. I just felt if I could help, I would."

Ms. Stevenson said the response from the Island's deaf community was impressive. "They were there lickety split when the word went out," she said.

Melissa Mahoney and her sister, Jill Nichols, both work in the Vineyard public schools and know sign language. "It was a little nerve-wracking but we were more than happy to help," said Ms. Mahoney of Vineyard Haven.

Interestingly, the portion of the deaf pilots web site, which detailed the events planned for last week's "fly-in" convention, showed the association had done its homework about the Vineyard.

It emphasized not only the Vineyard's unusual history with deaf residents but also the Waco biplane housed at the Katama Airfield.

"During the latter part of the 19th century and into the 1900s, there was a sizable deaf community on Martha's Vineyard . . . . There were so many deaf people on the Island-compared to the number of hearing residents-that it was normal to be deaf," the web site stated.