American Federation of Teachers President Albert Shanker acknowledged yesterday that he discussed the Professional Air Traffic Controllers Organization strike at a dinner meeting last September with a government official who had to vote a month later on revoking Patco's power to bargain for the nation's air controllers.

Shanker said that he learned in January that federal officials were investigating his meeting with Leon B. Applewhaite, a member of the Federal Labor Relations Authority. Applewhaite voted to decertify Patco. Both Applewhaite and Shanker have denied allegations that there was an attempt to influence the decision.

Patco attorney Richard J. Leighton said yesterday, however, that the union's principal concern is whether a Justice Department and FBI probe of allegations involving the dinner meeting may have had a "coercive effect" on the outcome of the FLRA's Patco decision.

On Tuesday, the U.S. Court of Appeals in Washington called for an independent investigation of any contacts or approaches made to any FLRA members before it voted to decertify Patco.

Leighton said that if Shanker was the labor official who talked to Applewhaite, his contact would not have been improper since Shanker is not a party to the Patco case. Leighton said, however, that the union wanted more evidence on any contacts before the vote between FLRA members and agents for the federal government, which is directly involved in the Patco case.

Leighton also said the union wants to develop facts about additional allegations that, prior to the vote, Applewhaite asked Reagan administration officials about his chances for reappointment to the FLRA and that he discussed the case at a Republican fund raiser. Applewhaite denies he discussed reappointment with the administration and said a comment made to him at the fund raiser about the case was an "offhand remark."

The allegations about Applewhaite were brought to the Justice Department by another FLRA board member, Henry B. Frazier III. According to court record, Frazier told the FBI that the day after the dinner meeting with the labor leader, Applewhaite, who had been in favor of decertification of Patco, "was vacillating" on his decision.

Frazier, who talked to Applewhaite about the meeting, told the FBI that the labor leader "made it plain" to Applewhaite that if he voted for decertification, he would be unable to get a job in the labor field when his FLRA term expired.

Shanker, who described himself as a good friend of Applewhaite's, denied any wrongdoing.