Ford Motor Co. is promising to install air bags for drivers in the majority of its North American cars produced after Sept. 1, 1989 -- if the federal government agrees to push back a deadline requiring automatic crash protection for all front-seat occupants.

The company wants to amend an already controversial 1984 ruling of the National Highway Traffic Safety Administration that critics charge could allow auto makers to escape installing air bags or other automatic crash-protection devices altogether.

Under the rule, car manufacturers are required to install some form of automatic protection for drivers in 10 percent of their 1987-model cars. All new cars must have such protection for all front-seat occupants by the 1990 model year.

But the rule would be suspended if states with two-thirds of the U.S. population pass mandatory seat-belt-usage laws by April 1989.

Auto and casualty insurers and car-safety advocates roundly condemned what they called the "trap-door provision" in the 1984 rule. But the two groups took issue with one another yesterday in assessing Ford's proposed amendment.

The Ford proposal ensures the production of a large fleet of air-bag-equipped cars, whether or not the states pass mandatory seat-belt-usage laws, insurance industry officials said.

"Ford's promise to produce large numbers of cars with air bags is what we've been waiting for -- a breakthrough toward making them standard equipment at a reasonable price," said Brian O'Neill, president of the Insurance Institute for Highway Safety, which is based in Washington.

"We strongly support Ford's petition," said O'Neill, whose organization is the lobbying arm for auto and casualty insurers.

Jean C. Hiestand, general counsel for State Farm Insurance, the nation's biggest auto insurer, was equally ecstatic. "This is a most significant milestone in the history of car-occupant safety," Hiestand said.

"By 1990, we'll be talking not in terms of thousands, but in terms of millons of motorists who will be afforded air-cushion-system protection. We can only consider that good news," Hiestand said.

Not so, said Clarence Ditlow, director of the Center for Auto Safety in Washington, long the auto industry's most vocal critic on safety issues.

Ford's petition to modify the 1984 rule "ought to be rejected," Ditlow said. Ford's real goal is to reopen the rule and to find a way to "further delay mandatory installation of air bags," Ditlow said.

Ford's promise is a promise and nothing more, he said.

"I think that the Insurance Institute for Highway Safety and the insurance industry have forgotten the auto industry's longstanding opposition to air bags," Ditlow said. "They've forgotten that you've got to watch what the auto industry does and not what it says. What the auto industry says is not necessarily what it will do."

That criticism produced outrage at Ford.

The company's proposed amendment will help Ford "install more of its supplemental driver-side air-bag systems in the future than the 1984 regulation -- for technical reasons -- makes feasible," said Helen O. Petrauskas, Ford's vice president for environmental and safety engineering.

The amendment proposal is no ruse, Petrauskas said. Ford has the technology to install air bags for drivers in a majority of its North American cars. But "because significant uncertainties about passenger-side air bags have not yet been resolved," the company cannot offer a full-front automatic-crash-protection package, Petrauskas said.

Another option, automatic seat belts for front passengers, is not feasible at this point because the company needs more time to find a cost-effective way of producing a reliable automatic-seat-belt system, Petrauskas said.

Ford currently offers air bags as options on its Tempo and Topaz compact cars. But, since their introduction in the 1985-model year, Ford has sold only 10,000 of the air-bag models -- 5,000 of them to the government.

That seemingly weak performance proves that Ford "has no real intention of selling air bags," Ditlow said.

Nonsense, Petrauskas said. "You can't measure the success of the Tempo-Topaz air-bags program in sales figures," she said.