A U.S. District Court jury yesterday awarded $400,000 to a Vietnamese orphan who was aboard a jetliner that crashed during "Operation Baby Lift" -- a U.S. mercy mission flying refugees out of Vietnam during the fall of the U.S.-supported Saigon regime in April 1975.

The child, 6-year-old James Matthew Zimmerly, who now lives with his adoptive parents in St. Louis, was awarded the money by a six-member jury. It was the second time the case had been tried. An earlier jury declined to award anything to Zimmerly, while granting $1 million and $500,000, respectively, to Melissa Hope Marchetti and Michael Moses Schneider, two other orphans who were passengers on the same ill-fated flight. s

The new trial for the Zimmerly case was ordered last spring by Judge Louis F. Oberdorfer who cited racially prejudiced comments by lawyers for the Lockheed Aircraft Corp. that manufactured the aircraft, and possible jury confusion over financial settlement arrangements in the case.

Attorneys for Zimmerly, one of more than 100 orphans involved in the air crash litigation, contended that the child suffered brain damage when the Lockheed aircraft suddenly lost oxygen prior to the crash. The injury, called minimal brain dysfunction, resulted in a number of impairments, including learning and emotional problems, they said.

Zimmerly at present requires speech and physical therapy, will need some psychological counseling and has "guarded" chances for living a normal life, one court source said.

Charles R. Work, the court-appointed attorney assigned to monitor the interests of all the children involved in litigation here, said, "We are hopeful the result will help settle all pending cases and will speed our objective in getting help for all of the children involved in this matter."

Of 330 persons aboard the flight, 135 were killed, including 76 of 226 Vietnamese orphans. The defendents in the suits are Lockheed and the U.S. government, which had acquired the plane for use by the Air Force. Lockheed and the government will share the cost of the damage awards under terms of an agreement.