Frederick H. Weisberg, chief of the appeliate section of the city's Public Defender Service and Carlisle E. Pratt, a lawyer in private practice, were nominated by President Carter yesterday to fill vacant seats on the D.C. Superior Court.

Weisberg and Pratt were selected after a review of names submitted to the President by the D.C. judical nominating commission and are subject to Senate confirmation.

Weisberg, 33, is the first public defender to be nominated to the Superior Court bench. The Public Defender Service represents indigent defendants, primarily in serious felony cases in Superior Court.

A 1968 graduate of the University of Michigan Law School. Weisberg worked for two years as a trial lawyers in New York City and with Volunteers in Service to America, the domestic Peace Corps. He joined the Public Defender service in 1970.

Weisberg was a trial lawyer in the public defender's office until 1973, when he moved to the appellate section. In 1974, he was named chief of the appellate section, supervising eight lawyers and preparing appeals to the D.C. Court of Appeals, the U.S. Court of Appeals and the Supreme Court for clients represented by public defenders.

"I can't think of a more challenging, interesting and varied experience for a lawyer to have," Weisberg said yesterday of his nomination to the Court.

"Parts of it will be frustrating and extremely difficult, but on balance I think it will be . . . an exciting experience for me," he said.

Pratt, 54, is a partner in the Washington law firm of Pratt and Queen A former law partner of Theodore R. Newman Jr., now chief judge of the D.C. Court of Appeals. Pratt has practiced both civil and criminal law in the District for more than 26 years.

In 1950, Pratt graduated from the Robert H. Terrell Law School, which he said was established in the 1930s for black unable to attend segregated law schools. In the early 1950s, following integration of some law schools and the Supreme Court's decision outlawing segregation in public schools, Terrell was closed, pratt recalled.

Pratt said he considered a Superior Court judgeship "an excelent opportunity to make a substantial contribution to the legal health of the community . . ."

Pratt was nominated to fill the seat vacated by the retirement of Orman W. Ketcham, who left the Superior Court last month after a 20-year term, to join the staff of the National Center for State Courts in Williamsburg, Va.

Weisberg will replace Charles W. Halleck who left the court last week after 12 years, Halleck's two-year struggle for reappointment ended last May when Carter said he would not submit Halleck's name for confirmation.

The salary for a Superior Court judge is about $49,000 a year. Pratt said his annual earnings currently totally about $44,000 a year, and Weisberg declined to comment on his salary. If confirmed, both will serve 15-year terms.

In a related development, the Senate has confirmed the nomination of John Maxwell Ferren to a 15-year term as an associate judge of the D.C Court of Appeals, the city's highest judical body.

Ferren, 39, is a graduate of Harvard Law School and a partner in the law firm of Hogan & Hartson. The vacancy on the appellate court was caused by the death of Judge Austin Ficking.