Federal investigators said today that wind-sensing devices detected no dangerous conditions and that neither air traffic controllers nor the crew of Delta Air Lines Flight 191 expressed any concern before the wide-bodied jet crashed in flames on Friday, killing 131 on the aircraft and one passing motorist.

But investigators said that "wind shear" -- an overpowering downdraft -- remains one of the prime suspects in the crash because of the aircraft's reported sudden drop to the ground and because wind shear detectors are not yet sophisticated enough to detect all of the short-lived, violent weather phenomena.

Investigators today continued to sift through the rubble, which miraculously yielded up alive almost one in five on board. Local medical officials said 31 people on the wide-bodied Lockheed L1011, most seated in the smoking section at the rear, survived the crash. Many told stories today of amazing escapes as the jet slammed to the ground and broke apart short of its runway at Dallas-Fort Worth International Airport.

This morning, Delta began flying relatives of the passengers and crew members who died to Dallas to help identify the burned and mutilated bodies. They were asked to bring dental records and fingerprints, partly because Dallas County Medical Examiner Charles Petty said he would prefer that relatives not view the bodies. "This is not a clean, neat scene," he said.

None of the passengers was listed as being from the Washington area, but one of the surviving flight attendants, Vicki Lee Foster, 29, was a native of the District.

Rescuers spent up to four hours Friday night digging through wreckage to find survivors. Among others, a female passenger in the rear section who had fallen into the luggage compartment was buried under hundreds of pounds of cargo but was saved.

A team of about 100 accident investigators from the National Transportation Safety Board and the airline industry began gathering here within hours of the crash. Today, they searched through scattered rubble and the charred wreckage of the tail section, by far the largest surviving piece of the plane, looking for clues as to what caused the crash.

The "black boxes" -- the cockpit voice recorder and the flight data recorder -- were recovered and dispatched to Washington. The investigators also took possession of the tape recording of conversation between airport traffic controllers and the pilot as Flight 191 was approaching Dallas.

In another quirk of survival, two dogs jumped from the wreckage, startling investigator Armond Edwards as he pulled the flight recorders from the tail section.

Safety officials said that as of this afternoon they could not pinpoint a reason for the disaster, although they appeared to be shying away from the possibility the plane was struck by lightning during a passing thunderstorm and toward the possibility of wind shear.

Safety board investigators said a preliminary review of cockpit and control tower recordings showed that the pilots expressed no concern as they approached the airport in a driving thunderstorm and controllers delivered no warnings of adverse conditions.

Retired Coast Guard admiral H.G. Patrick Bursley, a member of the safety board and the senior federal official on the investigating team, said the wind shear alert system at the airport, similar to those at major airports around the country, generated no warnings in the 15 minutes before the crash.

Bursley said pilots who approached on the same route just before the crash did not find downdraft conditions.

But Bursley said, "There could be a major wind shear phenomenon and the sensors would not pick it up."

Bursley said the safety board's preliminary findings, based on "a first raw appraisal" of the recordings, also indicate the Delta flight was on a proper course to the runway as it approached from the north through heavy rain and lightning.

"There's nothing in the cockpit voice recorder in the preliminary reading that indicates the pilot was conscious of trouble," Bursley said. "There was no indication of anything unusual. Preliminary indications are that he the pilot was within a very few degrees of course until the moment of impact. We do have a recording that comes down to a very sudden stop that would be analogous with impact."

Relying on descriptions of the scene from survivors and eyewitnesses, safety board spokeman Ira Furman said, "Obviously wind shear has to be one of the major areas of investigation."

Wind shear is a sudden change in wind speed or direction, often during a thunderstorm. The phenomenon sometimes causes an intense downdraft and side drafts that can leave a plane either being pushed downward or, more likely, in a near stall because of violently shifting side drafts.

Like almost every other airport, Dallas-Fort Worth has a "low-level wind shear alert system." Airport officials said the system was in operation Friday night.

This system consists of a central wind gauge at the heart of the field and five remote gauges at the edges. In case of a sharp variance in wind conditions between the central gauge and any of the remote sensors, traffic controllers can alert pilots with a warning such as, "Heavy wind shear in northeast quadrants."

Some witnesses said one or more lighting bolts appeared to hit the plane as it approached the field.

But Rudolf Kapustin, the safety board chief investigator here, said lightning was unlikely to have been a factor. "These jetliners are all electrically grounded so lightning shouldn't hurt," he said.

Flight 191, flying from Fort Lauderdale to Los Angeles, was coming in for an intermediate stop here in a driving thunderstorm at 6:05 p.m. CDT when it veered sharply downward, clipped two cars on a peripheral highway just north of the airport, and then skidded across the airport grass. The plane crunched into a pair of 2-million-gallon water tanks and burst into flame.

The rear section -- the tail and the last 20 or so rows of passenger seats -- broke off and came to rest burning but intact on a swampy airport field. The survivors then leaped from the sawed-off fuselage to safety.

The crash marred three of the best safety records in aviation. The airline, the airplane and the airport all are ranked among the safest in the industry.

The crash was the first by a major carrier at the airport, which has been a favorite of pilots since it opened in December 1973. A Delta plane had not crashed since July 1973 when 88 people were killed at Logan Airport in Boston.

Delta has 38 Lockheed L1011s in service and James Ewing, Delta's director of public relations, said they have an excellent record. "They are a marvelous airplane," he told United Press International. "It's incredible to me anything like this might have happened."

Of the 250 three-engine L1011s manufacturered from 1968 to 1983, all but three are still flying, Lockheed spokesman Rich Stadler said. Only one had crashed and that was blamed on pilot error.

The crew also had a long service record.

The pilot, Capt. Edward Michael Connors, 57, was a Navy veteran with 31 years of commercial flight experience. He flew for Northeast Airlines for 18 years before it merged with Delta in 1972. A native of Boston, he had been flying the L1011 since 1979.

First Officer Rudy P. Price, 42, a native of Philadelphia, had been a flight training instructor for the aircraft. He had been with Delta since 1970.

Second Officer Nick N. Nassick, 43, had been with Delta since 1976. He was a native of New Kensington, Pa.

The eerie scene where the smashed plane laid strewn in thousands of pieces on the grass was alive today with investigators, press and politicians.

As passenger jets floated in at the rate of one-per-minute to the runways just behind them, a large squad of Delta employes carrying bright yellow trash bags searched for any valuable items.

Safety board experts were studying the remnants of wings to see how the plane was configured as it came in. "If we know how the crew had the flaps set, we'll know something about what they thought was happening," explained Furman of the safety board.

A close look at the remnants of the giant plane made it seem miraculous that 31 of those aboard could have survived. Another miraculous survivor was Anthony Rogers, who said he was driving northward on State Highway 114, which skirts the edge of the airport.

"The rain was so hard you couldn't see 30 feet in front of you," Rogers said. "All of a sudden it seemed like I just caught a tire, a glimpse of a tire, and a big jolt just bounced my car. Stunned but unhurt, Rogers was able to pull his car to the side. As he did so he saw the plane's landing gear crush a Toyota driving just behind him on the same road. The motorist in that car was killed instantly.

By late today, 12 victims have been positively identified of the 121 bodies at the Dallas County morgue, medical examiner Petty told an afternoon news conference. An additional "tentative identification" has been made of another 12 victims, he said. He said a search of the crash site continues.

Petty said the major cause of death was "massive impact," and that many bodies had been dismembered or badly disfigured by the crash, explosion, and fire. "There are 121 bodies, and a few body fragments that . . . perhaps represent others . . . . "