A Western Airlines DC10 crashed at Mexico City International Airport shortly before dawn today, killing at least 71 of the 88 persons aboard and an airport truck driver.

Western Flight 605, arriving here from Los Angeles, landed, apparently in error, on a closed runway, hit a cargo truck, destroyed part of its landing gear and then careened into airport service buildings, 1,500 yards away. The plane caught fire and exploded.

Mexico's Civil Aviation Authority said a recording of the conversation between the pilot and the control tower indicated that the plane was given landing clearance on "runway 23 -- right." Instead, the report said, the plane "tried to land on runway 23 -- left [parallel to it], which had been closed since Oct. 19 for repairs. All airlines had been notified of this closure. As the Wetern Airlines plane approached, it was told to land on runway 23 -- right."

Today's was the first accident involving a McDonnell Douglas DC10 since a similar plane crashed in Chicago May 25, killing 273 persons. As a result, U.S. authorities ordered all DC10s grounded between June 6 and July 13 until the integrity of the engine mounting system was investigated.

[There was no indication from early information available in Washington that the troubled DC10 had malfunctioned. "It looks so far like a strictly operational accident, not a hardware problem," said a senior federal official.]

Although it was still dark at the time of today's accident, the Mexican report said visibility of two nautical miles was adequate. Twenty-five minutes earlier, a Mexican airliner also arriving from Los Angeles landed normally. However, later in the morning, visibility was reported at zero.

As the Western airliner touched down on the "wrong runway," the official report said, the pilot apparently attempted to avoid the cargo truck parked there. It touched down outside the white lines of the runway, but it hit the truck, killing the driver. With the landing gear damaged, the pilot then seemed to have tried to lift the plane off again but lost control.

Heavy gray lines across two runways and the taxi area showed how the plane veered sharply right toward the edge of the airport. It hit a mobile lounge garage, then spun around and smashed into an Eastern Airlines service building, which collapsed over the front of the plane.

The victims included all three cockpit crew members and eight of 10 flight attendants.

U.S. officials in Washington said they were investigating reports of a possibly confusing runway-light situation. tAccording to those reports, the approach lights had been turned on for the closed runway -- runway 23 left -- but the actual runway lights themselves were on only for runway 23 right.

The airplance was making a nonprecision appreach" in fog because the more-precise instrument landing system on runway 23 left was inoperative. That meant that, in darkness and fog, the pilot would have to rely primarily on his eyesight and outside lighting cues to land the plane.

The pilot told the tower, according to preliminary reports received in Washington, that he "did not have the runway in sight" and was planning to "go around" just as the plane struck the ground.

In Washington, officials pointed out that almost three-fourths of all major aviation accidents occur during approach and landing and most of those accidents involve human failure -- by pilots or air traffic controllers or both.

The Mexico City Airport has been officially rated "seriously deficient" by the International Federation of Air Line Pilots because of inadequate navigational aids, too high a frequency of radar failures, and the lack of equipment called "runway visual range," which electronically measures visibility in fog. When such equipment is not available, such measurements are made by human estimate.

"As the plane came toward me the right wing [which contains fuel tanks] was on fire," said Vicente Barrajas, who was waiting for the plane in a food service truck nearby. "When it crashed into the building there was a hugh fireball and a terible explosion. Then everything was a sea of fire."

Barrajas and other witnesses said airport firemen, stationed a few hundred yards away, arrived within "two or three minutes."

Firemen helped by custom officials immediately began pulling bodies from the wreckage but many appeared already to have been burned.

"I only saw one young woman climbing out of the wreck by herself, and I saw about five people alive with their legs mangled," one of the firemen said.

The young woman, suffering serious leg wounds, told a reporter that people in the plane were "fully aware that we were crashing. People screamed, it was like being in hell."

By 6:45 a.m., one hour after the accident, hundreds of firemen, Red Cross workers, police, and Air Force rescue workers still were climbing among the twisted steel of the fuselage and the smashed concrete of the buildings.

A row of about 30 bodies, many unrecognizably burned, were lined up in a closed compound of the post office building next to the wreck.

In the thick fog which later enveloped the airport, a slice of ripped fuselage eight yards long stood like a tragic black monument against the gray dawn. But there was little else that vaguely resembled the DC10 in the red-and-white Western Airlines colors. Two engines were reduced to a clump of distorted cables and melted steel. The tail engine was tossed a hundred yards away, against the concrete wall that separates the airport grounds from the street. A heavy chunk of the left wing had flown into a house across the street 100 yards away, reportedly wounding a couple and their two young children.