AFL-CIO President Lane Kirkland accused the Reagan administration yesterday of misleading the public by insisting that domestic airways are safe in the absence of nearly 12,000 striking air traffic controllers fired by the government.

"When they insist now that the air traffic system is safe and adequate with less than half a crew of less-skilled strikebreakers, I am reminded of an old saying: 'The louder they boast of their honor, the faster you should count the silver'," Kirkland said of the administration's claims.

Kirkland's comments -- his latest attack on Reagan's domestic policies -- were made in an address here at the triennial convention of the Seafarer's International Union.

"Do not be misled by the screen of government smoke about the expendability of these 12,000 locked-out controllers," the labor leader said, implying that, somehow, Reagan will have to rescind the mass dismissal order he issued Aug. 5, two days after the Professional Air Traffic Controllers Organization began its national strike.

But while the estimated 300 SIU delegates were applauding Kirkland's speech, the administration was going about its business yesterday, training new controllers, issuing decisions on responses to dismissal notices and keeping what it said was 75 percent of all daily domestic air traffic aloft.

According to the Federal Aviation Administration and the Office of Personnel Management, the figures yesterday looked like this:

Nearly 11,400 preliminary dismissal notices, so-called "proposals to remove" from work, have been sent to striking controllers.

About 8,300 controllers have responded orally or in writing to their preliminary notices, asking that the notices be withdrawn.

The FAA has rescinded only 33 of its firings, mostly because the affected controllers offered proof that they were not strike participants, or that they did not participate in the walkout voluntarily.

Final dismissal notices have been sent to 3,700 controllers.

The Office of Personnel Management has received 117,498 applications for air traffic controllers' jobs, which pay an average of $33,000 a year.

The FAA Academy in Oklahoma City, Okla., is operating 16 hours daily, training 432 replacement controllers. Academy spokesman Mark Weaver said the school soon will go to a 24-hour schedule, with the aim of producing 5,500 to 6,000 new controllers within a year.

Nearly 10,000 controllers, including supervisors and controllers on loan from military services, were conducting air traffic yesterday. About 17,200 controllers normally do the job.

Meanwhile, rumors continued to float in PATCO and other organized labor circles that the administration would relent and, in a public, politically minded display of mercy, rehire all or most of the controllers it has fired. But FAA and White House officials gave short shrift to that speculation yesterday.

Transportation Secretary Drew Lewis "has said time and time again that there is no deal," said FAA deputy spokesman Dennis Feldman. He said Lewis would stick to his position that only those controllers who could prove they were not on strike, or who were harassed or otherwise forced to strike, would be rehired. A key White House domestic policy official, speaking on background, said yesterday that "there is no evidence, none that I can see," that Reagan or Lewis will change their positions on the firings.