ROMULUS, MICH., DEC. 4 -- The crew of a Northwest Airlines DC-9 passenger jet realized too late that it had strayed onto a fog-shrouded runway at Detroit Metropolitan Airport here, where the aircraft was slashed and set afire by the wing of a Northwest 727 jet that was racing toward takeoff, federal investigators said tonight.

Reporting preliminary findings in the investigation of the fiery collision here Monday afternoon, National Transportation Safety Board member John Lauber said the DC-9 crew members told airport ground controllers they were having trouble "keeping track of where they were" as they made their way through the fog. The DC-9 reported missing the first taxiway turnoff it was assigned and was given another taxiway to follow to the end of the runway for its takeoff on a scheduled flight to Pittsburgh, he said.

But the two-man crew, commanded by veteran pilot William Lovelace, who had just returned from a five-year medical leave because of kidney stones, turned instead into the oncoming traffic of an active runway.

"It was reported in the last few minutes before the crash by the captain and the first officer that they were aware they were on Runway 21 Center and both reported seeing the 727," Lauber said. "After that, things happened very rapidly."

Lauber said "less than a minute" passed between the time the DC-9 crew realized it had turned onto the runway and the collision. He said he did not know whether the DC-9 crew had time to try to maneuver the aircraft off the runway.

The right wing of the 727 slashed almost the entire length of the smaller DC-9 and cut off its right engine, mounted near the tail. Airport officials said the resulting fire was put out in about three minutes, but it gutted the DC-9 down to its window level and charred the aircraft's bright red tail section.

Eight people aboard the DC-9, including a veteran Northwest Airlines flight attendant, were killed when the fire engulfed the passenger compartment.

Snow flurries swirled across the airport as the safety board began its investigation early today. The two aircraft, about 2,500 feet apart and facing in opposite directions, remained where they had come to rest after the accident. Late today, both planes were towed to a Northwest hangar, and the 8,500-foot runway was reopened to normal traffic.

By early tonight, the Wayne County medical examiner's office had identified five of the eight people killed. The exact causes of their deaths were not immediately announced, but the victims apparently were badly burned. "They were not viewable," said an official of the medical examiner's office.

Twenty-one people aboard the DC-9 were injured in the accident and one remained listed in critical condition with burns tonight.

Lauber said there were "numerous conversations" between ground controllers and the DC-9 as the aircraft tried to make its way through the fog to the end of the runway. He said a third Northwest aircraft reported hearing an unidentified aircraft's crew say "they were unsure where they were." But Lauber did not disclose details of the conversations between ground controllers and the DC-9, which are preserved on tapes being examined by the safety board.

However, James C. Morin, a lawyer for the National Air Traffic Controllers Association, said he had heard the tape of a conversation between the pilot and the airport tower that indicated the DC-9 crew had become "somewhat disoriented" in the fog.

When asked by a controller to give his position, the pilot radioed, "We're not sure. It's so foggy out here, we're completely stuck here." Then the pilot said, "Looks like we're on 21 Center here."

This reported position alarmed the controllers because 21 Center, or 21C, is the designation of the center runway when aircraft are headed south, as the DC-9 was. For the 727, which was racing northward at more than 100 miles an hour, the same runway is designated 3C. The direction in which the runway is used depends on which way the wind blows.

"You say you are Runway 21 Center?" the controllers asked the DC-9, according to Morin.

The pilot replied, "We believe we are. We're not sure."

The controller then ordered, "If you're on 21 Center, taxi off that runway immediately, sir."

That was the last exchange before the collision, NBC said.

At a news conference here this afternoon, Bob Gibbons, a Northwest spokesman, suggested neither aircraft should have been cleared to leave the terminal because of poor visibility. He said takeoffs from the center runway here require minimum visibility of one-quarter mile but "apparently the visibility was less than that" at the time of the accident.

Gibbons said he based his assertion on accounts of witnesses, including a pilot for a private firm who was a passenger on the Memphis-bound 727.

However, Lauber said tonight that airport weather advisories 15 minutes before the accident, when the DC-9 left the gate, and just after the collision reported visibility of one-quarter mile for the runway where the accident occurred.

Meanwhile, another organization with an interest in the outcome of the investigation -- the Air Line Pilots Association -- issued a statement in Washington sharply criticizing what it called "the premature release of information by interested parties" to the accident.

Gibbons identified the dead flight attendant as Heidi Joost, 43, of nearby Dearborn, Mich., a 22-year employee of the airline.

Gibbons also provided the first information on the flight crews of the two aircraft. He said Lovelace, 52, who has a total of 24 years' flying experience with Northwest, returned from leave on Oct. 22 and was given two weeks of ground school training and 13 hours of experience in a flight simulator.

Between Nov. 25 and 30, Gibbons said, Lovelace made 12 trips totaling 25 hours flying, including five flights in and out of the Detroit airport, under the supervision of a Northwest instructor who certified him as qualified to command a DC-9. Monday's flight to Pittsburgh was to have been Lovelace's first without a supervisor since returning from leave.

Gibbons said Lovelace, First Officer James Schifferns, a 20-year Air Force veteran hired by Northwest seven months ago, and the 727's three-member cockpit crew were interviewed today by safety board officials but had no public comment.

Staff writer Bill McAllister in Washington contributed to this report.