Since 1960, major airlines have been constrained by a Federal Aviation Administration rule that forces pilots to retire from flying at age 60 - regardless of health, ability or the desire to stay on.

Afraid that older pilots might fall victim to subtle ravages of time, the FAA has spent 30 years shuffling data to prove that only young pilots are safe pilots.Now these assumptions are being challenged.

"We're concerned about the inadequate seasoning we're seeing in the cockpit nowadays," says James Danaher, chief of the Division of Human Performance at the National Transportation Safety Board.

NTSB records show several accidents involving youth, scant training and lack of experience.

For example, on Feb. 24, 1989, the cargo door on a United Airlines 747 blew open, destroying two engines and ripping a 10-by-15-foot hole in the front fuselage. Nine passengers en route from Honolulu to New Zealand were sucked into the void.

At the controls was Capt. David Cronin, 59, a 35-year veteran of United. Cronin knew his fuel-laden plane weighed approximately 700,000 pounds - close to maximum.

If he lowered the landing gear, it would create drag and bring the plane down more quickly, meaning they might not make it back to Honolulu.

So Cronin did what few younger pilots might have thought to do: He opted to keep the landing gear up and try for greater distance.

After their safe landing, 328 passengers and 17 flight-crew members gave Cronin a rousing cheer.

But within weeks Cronin was out of a job. United kept its damaged 747 but had to retire its captain, who had just turned 60.

The FAA dismisses such stories as anecdotal. But statistics and hard evidence also support a change in the regulation.

The dispute over data is complicated by the fact that civil aviation is divided into three groups: major airlines, commuter airlines and general aviation.

Major-airline pilots fly on large, reliable jets and undergo many hours of simulator testing. They have at least two physicals a year, including an annual EKG after age 40. Their safety records are superb.

Commuter airlines primarily use planes with 30 seats or fewer. Although their accident rates are higher and their pilot standards are lower, pilots of these planes are not subject to the Age 60 Rule.

General aviation includes small-craft flying with no age limit, little training and minimal standards. Predictably, this group's accident rate is highest of all.

In analyzing the accident data, the FAA has combined major-airline, commuter and private-plane statistics to show fewer accidents for pilots under 60.

If you exclude them from the data, it turns out that among the remaining pilots, the 60-plus group has a lower accident record than the 30-to-40-year-old group.

Although most major airlines have supported the Age 60 Rule, some of the commuter airlines are having second thoughts.

"The pilots join the commuter airlines, then leave in a couple of years to join the majors," says Earl Snow, vice president of Utah's SkyWest Airlines. "If we in the industry could slow down the attrition rate in the majors, we could keep our (commuter) pilots around longer, and maybe make them into better pilots."

Since commuter airlines have an accident rate about 41/2 times worse than major airlines, slowing down their pilot turnover would make sense.

Some who once favored the Age 60 Rule are starting to have doubts.

Dr. George Kidera, a former president of the Aerospace Medical Association, was on the panel that originally wrote the rule.

"We knew it was arbitrary," he says. "But we just couldn't accurately predict which pilots were likely to fall ill.

"Now we can, so there's no reason not to let a qualified pilot fly beyond age 60."