WASHINGTON - The government told passenger airlines Wednesday they'll have to do more to ensure pilots aren't too tired to fly, nearly three years after the deadly western New York crash of a regional airliner flown by two exhausted pilots.

The Federal Aviation Administration's update of airline pilot work rules, some of which dated to the 1960s, reflects a better understanding of the need for rest and how night shifts and traveling through time zones can increase errors.

"This is a big deal," Transportation Secretary Ray LaHood said. "This is as far as our government has ever gone" to protect the traveling public from pilot fatigue.

Carriers have two years to adapt to the new rules. The FAA estimated the cost to industry at $297 million over 10 years, a fraction of the $2 billion a year that an airline trade association had estimated the draft proposal released by FAA over a year ago would cost.

The airline industry had opposed the draft rule as too costly for the safety benefits it would achieve. But FAA officials made substantial changes to the final rule to lower the cost. Several expensive reporting and training requirements were eliminated.

Safety advocates have been urging FAA for over two decades to update pilot work rules, but previous efforts stalled after airlines and pilots unions were unable to agree on changes. Those efforts were revived after the February 2009 crash near Buffalo that killed 50 people. Families of the dead have lobbied relentlessly for more stringent regulations to fight pilot fatigue.

The rules would limit the maximum time a pilot can be scheduled to be on duty - including wait time before flights and administrative duties - to between nine and 14 hours. The total depends on the time of day pilots begin their first flight and the number of time zones crossed.

The maximum amount of time pilots can be scheduled to fly is limited to eight or nine hours, and pilots would get a minimum of 10 hours to rest between duty periods, a two-hour increase over the old rules. The minimum amount of time off between work weeks will be increased 25 percent, and there will be new limits on how many hours per month pilots can fly. Pilots flying overnight would be allowed fewer hours than pilots flying during the day.

But cargo carriers - which do much of their flying overnight when people naturally crave sleep - are exempted from the new rules. The FAA said forcing cargo carriers to reduce the number of hours their pilots can fly would be too costly when compared with the safety benefits.

Imposing the rules on cargo airlines like Federal Express or United Parcel Service would have added another $214 million to the cost, FAA officials said.

The exemption for cargo carriers, which runs counter to the FAA's goal of "one level of safety" across the aviation industry, drew strong criticism from pilots unions.

"To potentially allow fatigued cargo pilots to share the same skies with properly rested passenger pilots creates an unnecessary threat to public safety. We can do better," said Robert Travis, president of the Independent Pilots Association, which represents UPS pilots.

National Transportation Safety Board Chairman Deborah Hersman, while calling the new rule "a huge improvement," also expressed dismay that cargo operations weren't included.

"A tired pilot is a tired pilot, whether there are 10 paying customers on board or 100, whether the payload is passengers or pallets," she said.

LaHood said he plans to invite top officials from cargo airlines to meet with him next month so that he can urge them to voluntarily follow the new rules.

The charter airlines that transport nearly 90 percent of U.S. troops around the world had also lobbied heavily for an exemption to the new rules, saying military missions could be jeopardized. But FAA officials rejected those pleas.

The rules will prevent about one and a half accidents a year and an average of six deaths a year, FAA officials predict. They should also improve pilots' health, officials said.

Jean Medina, a spokeswoman for the Airlines for America trade association, said the group is reviewing the new requirements. "We support changes to the rule that are science-based and that will improve safety," she wrote in an email.

Researchers say fatigue, much like alcohol, can impair a pilot's performance by slowing reflexes and eroding judgment.

The changes replace "rules that were dangerously obsolete and completely ineffective," said Bill Voss, president of the Flight Safety Foundation in Alexandria, Va. "The rule applies fatigue science in a way that makes sense."

Susan Bourque, who lost a sister in the Buffalo air crash, said she was particularly pleased that the rule will require pilots to sign a statement before each flight stating that they are rested and fit for duty. "It's a pretty good day," said Bourque, of East Aurora, N.Y.

Scheduling wasn't an issue in the Buffalo accident, but NTSB concluded that the pilots' performance was likely impaired by fatigue.

Neither pilot appeared to have slept in a bed the previous night. The flight's captain had logged onto a computer in the middle of the night from an airport crew lounge where sleeping was discouraged. The first officer had commuted overnight from Seattle to Newark, N.J., much of the time sitting in a cockpit jumpseat. They could be heard yawning on the ill-fated flight's cockpit voice recorder.