International comparisons on aviation are at best speculative, but Bolivia is unquestionably one of the most dangerous countries in the world for flying.

It has treacherous winds, high Andean peaks and runways that look as if they might have been designed by sadists. Some are little more than rough strips carved out of the jungle or into the sides of mountains. Anthills with walls like cement that rise overnight can play havoc with landing gear.

It is dawn and a mechanic for North East Bolivian Airlines and I wait under the wing of a DC4, a four-engine transport plane that began its career about 40 years ago. It is part of the fleet of vintage World War II planes--commonly referred to as "flying coffins"--that bring cargoes of fresh meat from the jungles to the capital of La Paz, Cochabamba and the tin-mining regions.

The weather is not good in the north, and the flight, which has been delayed twice, may have to be delayed again. After two hours, the copilot and manager step out of the adobe building that serves as the airline office and gives a thumbs-up sign to the mechanic.

Our plane will be a Curtis 46, a two-engine transport built in 1942. Cargo is lashed to the center aisle with rope.

Capt. Luis Ortiz, who is dressed in a black leather jacket and brown boots, has flown the meat runs since they began 20 years ago. He and the mechanic have walked away from more than one crash. The copilot is 22 years old and has been flying the cargo planes for only a few months.

Bolivia, a country twice the size of Spain, has a vast tropical lowland in the north and west called the Beni, a green savanna that is one of the world's great natural pastures. Several months of the year, the Beni is almost inaccessible because of fierce rains, and the rest of the year it is accessible only by river boat and plane.

Cattle were introduced in the 17th century by Jesuit missionaries, and huge herds flourished on the savanna, reaching 2 million head by the turn of the century, according to some estimates. More recently, the wild cattle were crossbred with the humpbacked zebu bought from India via Brazil.

The plane moves slowly off the gravel lot onto the cement. The mechanic sits atop the cargo boxes. After takeoff, he watches the left propeller intently. Then he moves to study the roaring engine on the other side. His expression is serious. Finally he looks back at me and puts both thumbs up.

"The clouds are not going to break," says the mechanic. We soon find ourselves enveloped in cloud cover, and visiblity falls to zero.

With no radar, and never knowing the weather conditions until aloft, the pilot must navigate by his watch and compass. The plane must thread its way through a mountain pass before reaching the jungle.

"We go five minutes now," says the pilot, "and then turn 30 degrees." We thread our way through the peaks looking at nothing but the white mist in front of the windshield and a wristwatch.

The copilot is dripping with sweat--it trickles down his cheeks and droplets hang on his ear lobes. The pilot is not outwardly nervous, but has the annoying habit of glancing over his shoulder every few minutes to check on the left propeller. I rememberthe engine had backfired during takeoff.

Finally we break into clear sky. The cliffs of the Andes behind us, we are suddenly faced with a limitless green flatland.

Muddy rivers snake back and forth through the undergrowth below. After a few more minutes we nose down below the low cloud cover and skim over the treetops to look for our landing field.

The landing is surprisingly smooth for a dirt field. We are outside a small village, San Lorenzo. Before the propellers stop, a truck backs up to the hold to carry away the supplies. Two sod huts with palm roofs lie just off the landing field, a cow wanders out in front of our plane and children climb on the tires.

The cargo unloaded, we take off and fly to Habana, a large cattle ranch outside of Trinidad, the provincial capital of the Beni.

Inside a tin-roofed shed near the strip, carcasses of beef hang from iron hooks. Indian butchers, who are said to work for little more than food and shelter, hack away with saws and knives at the decapitated cattle. The cement floor is slippery with pools of thick blood. The slaughter began two hours before, as soon as the news came in over the radio that we had taken off. Behind the shed is a corral holding five cattle.

"We usually land in the afternoon, and they do this during the night," the captain says, "If we can't take off by the next afternoon, all the meat is ruined."

In the pen several men have roped a bull and are pulling it toward the gate, where a bare-chested worker waits with a long knife. The bull, terror in his eyes, pushes its head downwards and the butcher slips the knife deftly into its neck. The bull looks stunned, backs off and falls, blood gushing onto the ground.

Rapidly the bull is decapitated by two workers, who then carve the meat off his face and take the thin strips to the women cooking nearby. The legs are severed and thrown into a pile.

A metal cable is attached to the hindquarters, and the carcass is hoisted by a winch to a metal rail. It is quartered as it moves along the rail, and at the end a powerful butcher severs the backbone with an ax, each blow sending a small white cross around his neck bouncing up into his face.

Two women bring us plates of meat and rice, which we eat around the rancher's small table.

As the last carcass moves down the rail, a ramp is constructed to the cargo doors of the plane. The rancher, sucking on a grapefruit, notes the weight as the Indian workers step on a scale, a side of beef balanced on their shoulders.

After depositing their sides of beef on the plane, the workers descend the ramp single file, blood running down their chests and knives bouncing against their thighs. The load on the plane is 11,000 pounds.

At takeoff the body of the plane groans and vibrates ferociously. The mechanic watches the propellers. No thumbs-up signal this time. The copilot is again sweating. The captain is stripped to his T-shirt. No one speaks.

About half an hour into the flight, heads dizzy from the altitude in the unpressurized cabin, the left motor skips a revolution and backfires.

"You get scared up here?" I ask the pilot impulsively.

"Every time it does that," he says.

The plane, clearly fighting under the weight, loses its thundering roar every so often, until we swallow and bring back the full power of the engines. The jungle breaks through the cloud cover now and then. The mechanic keeps reaching over the copilot's shoulder to move a lever, and at one point the copilot lurches the plane upward as he is jolted by the mechanic's unexpected move. The captain tells the mechanic to sit back.

At this point, there is nothing to do but wait. I offer everyone water, but no one takes any. We see nothing now but the cloud cover below us and the distant peaks of the Andes. I watch the figurine of Christ on the instrument panel and the nervous hands of the mechanic. We turn to reenter the pass we navigated this morning.

The final descent breaks some of the tension. We lower the nose and slow down as Cochabamba comes into view. The runway seems to inch toward us until we slip the tired plane onto the cement and all at once breath normally again, our bodies slumped back in the seats.