Crash Probe Focuses on Theory of Ice on Wings

RAISINVILLE TOWNSHIP, Mich. — Investigators, struggling through gritty, stinging sheets of blowing snow, focused Friday on the possibility that ice on the wings of a commuter plane caused it to nose-dive into a cornfield, killing all 29 people aboard.

They recovered both “black boxes,” containing recorded cockpit voices and flight information from the twin-engine Embraer 120 turboprop, operated by Comair, a regional carrier flying as the Delta Connection, when it crashed Thursday in a snowstorm. The boxes were shipped to Washington for analysis.

“We are especially pleased we located these recorders,” said John Hammerschmidt, a member of the National Transportation Safety Board, which is heading the investigation. Hammerschmidt refused to speculate on the cause of the crash, but an NTSB source close to the investigation said: “Obviously, we’re looking at the weather. Icing.”

The plane, made in Brazil and known as a Brazilia, carried 25 adult passengers, one infant, a pilot and co-pilot and one flight attendant. It had left Cincinnati at 2:53 p.m. EST and was 18 miles short of Detroit Metro Airport when witnesses said it rolled to the right and plunged straight down, nose first, into the cornfield, exploding on impact and drilling a black crater in the fallen snow.

“It’s not a pretty sight out there,” said Charles Chapman, a state trooper helping to maintain security at the crater and to recover the remains of the victims. “There are no whole bodies, just pieces of people scattered in the stubble. The plane must have come in almost straight down, because there is no path of destruction leading to the impact--just an oblong debris field.

“Underneath it’s blackened, but the snow is blowing, covering it with white. The snow helps. It’s not quite as shocking now,” Chapman said. The plane was rubble. “Small pieces. Not a lot of big pieces. It’s terribly cold out there. The snow is blowing, cutting. Visibility drops to 100 feet, then to nothing. We wear parkas, boots, insulated underwear. But it’s not enough. Not nearly enough.”

Hammerschmidt told reporters at a command center near the crash site that sheriff’s deputies and investigators were working in 15- to 20-minute shifts to keep from freezing. The overnight temperature was expected to fall to 10 degrees, with the windchill expected to fall well below zero. Country roads leading to the site were covered with snow, making it difficult to reach.

The voice and data recorders, commonly known as “black boxes” but painted orange to make them easier to find, were located in the center of the crater. The recorders are the size of rural mailboxes and are encased in heavy steel. They had suffered “some impact damage,” Hammerschmidt said, and were “sooted.” But he said recorders in worse shape have produced valuable data.

Hammerschmidt said the recovered flight data recorder was a modern variety that tracks 78 facets of flight, including altitude, air speed, acceleration, propeller speed and control settings. He said the data should help determine the cause of the crash. “We consider this a very open question,” he added, but acknowledged that the possibility of icing was “something we are looking into.”

The focus tightened on icing when investigators found all eight propeller blades from the Brazilia, as well as all eight of its blade tips, within the debris field. This indicated that neither of the two four-bladed propellers had disintegrated in flight. Brazilias and other turboprop commuters have experienced propeller trouble in the past.

“The plane had three de-icing, or anti-icing, systems,” Hammerschmidt said. One was on the wings, he said, while another was on the leading edges of the propellers and the third was on the engine inlets. A crucial part of the investigation will be to determine whether all three of these systems were working properly.

Another sign pointing to ice problems came from pilots of other aircraft in the general area who reported icing in their routine weather observations. In general, these pilots reported light snow and mist with light winds and ceilings well above landing minimums, investigators said. But there were several reports of “light to moderate icing.”

One pilot reported severe icing conditions in an area near Findlay, Ohio, only about 100 miles from Detroit, at an altitude of 9,000 feet. The pilot made the report at 3:02 p.m., about 50 minutes before the Brazilia went down. Because of these reports, air traffic controllers had broadcast advisories of moderate icing in the general area near the crash site.

Ice disrupts airflow over the wings and causes planes to roll. It was responsible for the crash two years ago of an American Eagle ATR-72 turboprop commuter that rolled and then crashed near Roselawn, Ind., killing 68 people. The crash led to design changes in the aircraft, and pilots were advised to avoid icing conditions.

As investigators concentrated on the cause of Thursday’s crash, sheriff’s deputies and state troopers centered their efforts on finding remains of the victims. Up to 50 officers at a time combed the 100-by-200-yard debris field on the banks of the meandering River Raisin--a small, ugly creek, about 30 yards wide at most, caked with chunks of brown ice.

Skies were gray, and the officers were pelted by snow and hammered by 25 mph winds. It blew across 6 inches of freshly fallen dry snow that flew into the air in opaque sheets that stung the skin and blinded the searchers.

The FBI sent a disaster-and-evidence-recovery team to work with local officials and the Red Cross. Team members stepped carefully through the burned and splintered wreckage.

The deputies carried victims’ remains to a hangar nearby. “Obviously,” Hammerschmidt said, “the first priority of ours is to recover the remains.”

None of the victims was from California.

Among the dead, however, was a woman traveling from Colorado to Michigan for a memorial service for a brother who was one of six people killed on Dec. 22 when a cargo jet crashed into a mountain in Virginia during a maintenance test flight.

One Detroit man considered himself extremely lucky. He had wanted to get home quickly to his wife and 19-month-old son, so he ignored his wife’s advice to wait for the commuter flight from Cincinnati.

Instead he rented a car and drove home. As he passed through Toledo, he heard on the car radio that the flight he could have boarded had crashed and everyone on it had died.

Times staff writers Donald W. Nauss in Detroit and Richard E. Meyer in Los Angeles contributed to this story.