A federal appeals court today ordered an end to delaying tactics that have extended a ban on landings by supersonic Concorde airliners at New York's Kennedy airport.

The three-judge court's decision would permit four daily Concorde landings at Kennedy to begin in 21 days, but lawyers for the Port Authority of New York and New Jersey, which owns Kennedy, said they will appeal to U.S. Supreme Court.

The port authority will request that its ban on Concorde flights remain in effect until the Supreme Court rules, a spokesman said.

In a decision critical of the port authority's refusal to address the politically sensitive issue of Concorde landings, Chief Judge Irving Kaufman of the Second U.S. Circuit Court of Appeals wrote:

"If ever there was a case in which a major technological advance was in imminent danger of being studied into obsolescence. This is it."

The court said, "The hour is a hand for the port authority's indefinite ban on Concorde flights to be recognized as an abdication of responsibility."

The ban was imposed more than 18 months ago because of fears the supersonic planes would greatly increase a noise levels at Kennedy which is in a heavily populated area. The airliner currently operates in the United States only from Washington's Dulles airport.

In tests by the General Accounting Office the Concorde has been found no noisier than other jets except on takeoff when it is twice as loud as the next most noisy planes. The appeals court decision, however, noted that the Concorde noise is below the ceiling that the port authority has used for almost 20 years.

Air France and British Airways have reported heavy losses on their Concorde operations and have said access to the New York market is the key to the Concorde's future. The two government-owned airlines are the only ones flying the Concorde, which was developed jointly by Britain and France at a cost of $3 billion.

Although today's decision was welcomed by spokesmen for Air France and British Airways, the court leaves the port authority with the option of setting new noise standards that could limit or ban Concorde landings at Kennedy.