WASHINGTON (AP) - Safety experts say airline travel has become so safe in the United States it's hard to justify imposing costly new safety rules on the economically fragile industry.

It's been 43 months since the last deadly domestic airline crash. That's the longest period without a fatal accident since commercial aviation expanded after World War II.

Government cost-benefit analyses value each life saved at $6.2 million. But modest changes in regulations can cost the industry hundreds of millions of dollars.

Bill Voss of the Flight Safety Foundation says the extraordinary U.S. safety record could be the single biggest holdup to future safety improvements. Federal and industry officials say they're making safety improvements without new regulations by mining voluntary databases to spot problems before they become accidents.

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