Soviet and American jet fighters roared overhead Sunday at the Farnborough air show as thousands of people previewed this week's exhibits of the aircraft and technology of 24 countries.

While organizers say the estimated 700 companies participating in the 40th anniversary exposition make it one of the best in the West, safety concerns were heightened by the worst-ever air show disaster Aug. 28 in Ramstein, West Germany, that killed 51 people when a flaming plane plunged into spectators."To compare to what happened at Ramstein a week ago, we would not contemplate or permit a crossover maneuver with a third aircraft flying at a right angle . . . toward the crowd," said Dan Honley, spokesman for the show. "That certainly would be against our regulations."

About 32,000 people also attended air shows Sunday at Dinard and Roanne, France, under tightened safety rules imposed after the Ramstein crash.

The aircraft in the French shows flew at minimum altitudes of 500 feet instead of the regulation 330 feet, and the Patrouille de France (Patrol of France) air force stunt team modified its program at Dinard to eliminate more risky crossover maneuvers.

Farnborough International '88, sponored by the Society of British Aerospace Companies, opens to potential buyers Monday and to the public Thursday. After the last show, exhibitors said they took orders for their products totaling well over $1.7 billion.

Honley said the safety regulations at Farnborough were last modified in 1986 and in-flight precautions have been constantly reviewed since the shows began in 1948.

All maneuvers conducted at Farnborough must be "fail-safe," which means pilots are required to fly parallel to or away from the crowd, he said.

"We do limit the pilots quite stringently here. They can only fly no lower than 100 feet if they have their wings level, straight and parallel to the crowd," he said.

"They've got to be up to 200 feet if they're making any maneuver at all, and if they're making a difficult maneuver, they must demonstrate to our flying control committee they can pull up 500 feet above the ground," Honley said.

Honley said at Ramstein, during an Italian demonstration, five pilots were flying parallel to the ground and the grandstands from the left and four were headed toward them from the right, when a 10th pilot flying between them toward the crowd miscalculated and caused the fiery collision.

The momentum of the 10th plane, flown by the squadron leader, carried it in flames into 300,000 people gathered at the U.S. Ramstein Air Base. Fifty-one people died and 418 were injured.

"The slightest miscalculation, the slightest misjudgment on the part of that 10th pilot and tragedy was inevitable and it sadly happened," Honley said.