The Professional Air Traffic Controllers Organization filed for bankruptcy yesterday, 11 months after calling a strike that led to the firing of 11,500 of its members.

"It's over for Patco; it's behind us," Gary Eads, the union's president, told reporters after filing papers with the U.S. Bankruptcy Court here. Eads, who became Patco's president in December after Robert E. Poli resigned, said the union is seeking to liquidate its assets, which he estimated as "several hundred thousand dollars."

Whether another union will be formed to represent air traffic controllers is unclear, although some observers believe that Patco leaders will try to form a new group under a new name that will seek to help fired controllers regain their jobs. "I think a union is going to come about, but where from I can't tell you now," Eads said yesterday.

He contended that the problems that led to the controllers' walkout last August were "not fictitious" and that the conditions of the reduced controller work force were "deteriorating."

Eads suggested that the administration policy against rehiring the fired controllers should be reconsidered, now that the union is dead and the president had "proven his point . . .

"If the dismissed controllers were reinstated, this nation's air traffic control system would be operating at full capacity in a matter of weeks, instead of years, and at a much reduced cost," he said.

The union's assets are to be distributed by a court-appointed trustee to the union's creditors. Claims against Patco's assets were estimated at about $40 million.

About $33 million is owed to the nation's airlines as a result of fines levied against the union for violating an injunction barring a strike. Another $1 million is owed to the federal government.

Patco's creditors contend that they also should have access to about $4 million that is held in what the union says is a subsistence "trust fund" not available to creditors and that will be dispersed to union members at some point.

A trial on the question of the fund has been scheduled for October.

"They call it a trust fund; we call it assets," said James E. Landry, senior vice president and general counsel for the Air Transport Association, a trade association of major airlines.