The Federal Aviation Administration yesterday proposed a significant and potentially controversial change in its regulations that would let each airline decide how it should meet federal safety standards.

Airline deregulation to date has consisted of eliminating rules on how airlines decide what cities to serve and what fares to charge. Now the deregulatory movement is entering the field of safety.

FAA officials, from administrator J. Lynn Helms on down, have been touting the safety proposal to the airline industry for more than a year under a concept it has come up with called "regulation by objective" (RBO).

They published it as a Notice of Proposed Rulemaking in the Federal Register yesterday along with the statement that RBO will let airlines "assess their operations and seek more effective and efficient methods of complying with safety objectives while maintaining the highest level of safety."

That has created concern among some aviation safety specialists that the bottom line will become the only thing that determines how well safety standards are met. The proposal is certain to renew the old argument about whether the FAA's prime responsibility should be to assure safe flight or promote aviation, both of which Congress has told it to do.

Current FAA regulations have two sections that apply to commercial airline safety: Part 121, for major airlines, and Part 135, for commuter airlines. Both parts spell out in great detail what an airline must do to qualify its crew members and to equip and maintain its airplanes.

Those sections would be replaced by a new Part 120, applying to all airlines, whether transoceanic or trans-state. Each airline would work out with the FAA its own approach to meeting the standards for everything from engine changes to crew training. Airlines that would rather operate under the old system could continue to do so.

The changes would not apply to federal standards for aircraft manufacturers.

There is already considerable cooperation between the FAA and the aviation industry in writing federal regulations and they are enforced to a great degree by the industry's own employes, who are frequently designated as responsible parties for many inspections and checks.

Further, many airlines have sought and received exemptions to sections of parts 121 and 135 if they have been able to demonstrate that their method provided just as much safety. What RBO would do is expand that concept.

Official industry response yesterday was cautious, because it was the first time the FAA had actually laid a document on the table and nobody had had a chance to study it. Spokesman for both the Air Transport Association of America, the big airline lobby, and the Regional Airline Association, the commuter group, said they would study it closely.

The Air Line Pilots Association had no comment, although many of its members and those of other industry unions are known to be concerned that RBO will mean fewer jobs.

On background, however, tongues were looser.

"I have a fundamental problem," one industry official said, "with the idea that the lowest common denominator wins, that we're going to compete to see how much we can save on operating rules. I've never heard anyone complain that the regulations are too strict."

The FAA noted that rules of the Environmental Protection Agency and the Occupational Safety and Health Administration have frequently stirred hot objection from regulated industries, but that "aviation safety regulations have not been similarly challenged, perhaps because the complex 'how to' regulations that grew over the last 40 years are serving the best interest of the regulated industry and the public, or perhaps because the aviation industry became accustomed to detailed safety regulations in the same manner that it became accustomed to economic regulation."

One source said that RBO process would not be subject to the same kind of public scrutiny that formal rules are and would reduce the ability of Congress to oversee the agency. "Unfortunately, crashes or enforcement investigations are the ultimate test of whether RBO is going to work," the source said.