American Airlines agreed yesterday to return to the bargaining table for one last effort to negotiate an agreement with its pilots union.

At issue is American's plans to fold the operations of recently acquired Reno Air Inc.--including Reno's pilots--into its system by the end of the month.

American said it had agreed to a request by special mediator George Nicolau to meet Monday with representatives of the Allied Pilots Association in an effort to reach a contract agreement on combining the two pilot groups.

The Allied Pilots Association, which represents American's 9,500 pilots, said it called a special meeting of its executive board for Aug. 17 to review progress at the bargaining table.

A company source close to the talks warned, however, that American plans to complete the integration of Reno Air on its own by Aug. 31 if no agreement is reached with the APA.

"We have agreed with the mediator to take one last shot at putting this deal together," the source said.

If the two sides fail to reach a negotiated agreement on the integration process, the union could seek a court injunction to stop the merger, claiming the unilateral action was a violation of the existing labor contract between the company and the union.

"We'd prefer an agreement rather than a discussion before a judge," said a company source.

The current dispute dates back to Dec. 23, when American completed the $124 million purchase of Reno, a low-fare carrier operating on the West Coast.

The APA immediately raised concerns about the acquisition and claimed it was a move by American to use the lower-paid Reno pilots to fly routes normally flown by APA members.

In February, APA staged a sickout over the dispute that basically grounded the nation's second-largest carrier. APA wanted Reno's pilots to be paid the same wages as American's pilots.

American then went to federal court in Dallas and won an injunction against the sickout. When the APA failed to immediately end the disruption, a federal judge fined the union $45 million. That case is being appealed by APA.

In March, the two sides agreed to try to negotiate a contract that would resolve the dispute. But after the agreement was reached, the APA executive board voted last weekend to add two major amendments. American refused to accept the changes and declared the deal dead.

The union would like pay boosts to Reno pilots to be retroactive to Dec. 23 rather than the Aug. 31 stipulated in the negotiated agreement.

The union also demanded that around 300 American pilots who were furloughed because of a previous marketing agreement between American and Reno before the Reno acquisition should be returned to work with full seniority and benefits as though they had never been laid off.

The company has refused, saying the two items would add $50 million to the purchase cost. American officials insist they cannot accept either change proposed by the APA executive board, even though both will be on the bargaining table next week.