Death Toll in N. Carolina Jet Crash Reaches 37; Wind Shear Suspected : Tragedy: The 20 victims who survived the Charlotte ordeal remain hospitalized. The USAir DC-9’s data and voice recorders are found.

The death toll climbed to 37 Sunday as federal officials finished the grim task of extracting bodies from the wreckage of a USAir jetliner that crashed here Saturday night.

The other 20 people aboard the plane remained hospitalized Sunday with injuries ranging from superficial to critical.

The DC-9 jet carrying 52 passengers and a crew of five on Flight 1016 from Columbia, S.C., was preparing to land at the Charlotte-Douglas International Airport during a violent thunderstorm when the pilot decided to abort the attempt and then turned away for a second try at a landing, officials said.

Witnesses said they heard the plane’s twin engines roar as the jet tried to regain altitude, but instead of climbing, the airliner slammed into the ground, coming to rest against a house and several trees.

The plane broke into three sections, scattering debris, and the wreckage burst into flames. Sources close to the investigation said the accident may have been caused by low-level wind shear--a phenomenon associated with thunderstorms that has been blamed for some of the worst jetliner crashes in U.S. history.

Wind shears--drastic changes in the direction that air is moving--can cause a plane to lose vital airspeed at dangerously low altitudes and crash without warning.

Meteorologists issued a wind-shear warning at the airport about a minute before the crash, and pilots of two other jetliners postponed their takeoffs because of the severe weather.

Federal investigators stressed Sunday that it is still much too soon to determine what went wrong on Saturday.

They said the jet’s two “black boxes”--recording devices that should reveal the cockpit conversations and as many as 40 technical aspects of the flight in the seconds before the crash--have been recovered from the wreckage but their tapes have not been fully analyzed.

However, a preliminary reading from the voice recorder indicates that the pilot of Flight 1016 announced that he was canceling his landing attempt after encountering a heavy downpour.

T. Jerry Orr, the manager of the airport said officials have not yet studied data from low-level wind-shear sensors on the airport grounds to see if wind-shear conditions existed at the time of the crash.

Other officials said the relatively unsophisticated sensors on the ground often fail to provide definitive data about wind shear.

More sophisticated systems are being installed at U.S. airports, and officials said the landing field here should get one within a few years.

A dramatic account of the crash was given Sunday by one of the survivors, Robert Thomas, 33, who was en route to Philadelphia with a friend and fellow resident of Phoenix, Steven Roy. The two had been planning a Fourth of July weekend holiday together.

Thomas, who suffered superficial burns and bruises but was otherwise unscathed, said he was asleep in an 11th-row window seat as the plane approached the airport Saturday night.

He said he awoke to the roar of the engine as the pilot advanced the throttles in a futile attempt to climb.

“When the plane first hit, I thought it was on the runway,” Thomas said from a wheelchair during a news conference at the Carolinas Medical Center. “But when I saw the debris flying I knew we were in trouble.”

Thomas said the impact threw him against the wreckage of what had been the seat in front of him, “and when I got up there was nobody left around me. . . .”

“I looked around and there was fire,” he said. “I looked over to the aisle where my friend was sitting, and he was buried in seats and shrapnel.” Thomas said he managed to unbuckle his seat belt and clambered to safety through the hole where the seats behind him had once been.

“There were lots of people all over the place,” he said. “They were alive, but they were lying on the ground.” Thomas was asked if his friend survived the crash.

“I don’t think so,” Thomas said softly, a shadow of pain crossing his face.

“You know, he’d helped me out of a lot of binds. We’d been together for a long time.”

John A. Hammerschmidt, a National Transportation Safety Board member who is heading up the federal investigation of the crash, went to the accident site Sunday and walked the path the plane followed after it slammed into the ground a few hundred yards from the runway where it had been attempting to land.

He said the plane followed a straight path after impact, scattering debris and broken tree limbs as it cut a swath through a small span of trees.

The plane glanced off a cinder-block foundation and struck two large oak trees, which withstood the impact, tearing the aircraft into three pieces.

The tail section came to rest against an unoccupied house. Officials said the sight of survivors stepping out through the wreckage of the house had led to earlier reports that there were people in the home who had been injured.

The middle section of the plane--the part in which Thomas was riding--largely disintegrated and burned.

The cockpit section, containing most of the flight crew, skidded a few yards farther and came to rest in the middle of a paved road.

Officials said all the flight crew survived.

Seth Schofield, chairman and chief executive officer of USAir, identified the pilot as Michael Greenlee, 38, of St. Paris, Ohio.

The co-pilot was identified as James Hayes, 41, of Woodstock, Ga. Schofield described the two men as “very experienced.”

He said Greenlee has 8,065 hours of flight time, with 1,910 of them in a DC-9. Hayes has a total of 12,985 hours, 3,120 in a DC-9.

Schofield said the plane that crashed was built by McDonnell Douglas in 1973 and had logged 54,000 hours of flight time.

He said the plane had just undergone an extensive overhaul.