Hackensack, N.J. ? On his 100th birthday this December, John M. Miller plans to head to his hometown airport, take the brown engine cover off his 1969 Beechcraft Bonanza and take to the sky.

The only thing standing in the way of Miller flying solo on the big day: medical clearance. Miller, an aviation pioneer who has flown everything from biplanes to commercial jets, insists he’s fit to fly.

More and more pilots are flying past 80, Federal Aviation Administration statistics show, a trend that has even inspired a national study of their safety records, in the hope of challenging insurance industry practices of penalizing older pilots with higher premiums.

More than 3,800 of the nation’s roughly 618,000 licensed pilots have reached 80, according to Federal Aviation Administration reports. The 80-and-over category has jumped 73 percent during the past five years, even as the total number of pilot certificates held has declined.

Like America’s drivers, general aviation pilots face no age limits. As long as a pilot can pass an annual or biannual physical, they can fly solo. Even without the physical, pilots – like Miller -can still get behind the controls if there is another medically certified pilot in the cockpit.

“A few years ago, people just didn’t think that anyone would bother to think about flying after 60 or 70 or 75,” said Herbert Sloane, a 91-year-old pilot from Alabama who is the secretary and treasurer of the 531-member United Flying Octogenarians.

“People our age were supposed to sit in rocking chairs,” he said, attributing the growing number of old pilots to “men taking better care of themselves and insisting on doing things that, a few years ago, were denied them.”

Ed Hoffmire, a pilot in his 90s from Clifton, N.J., no longer flies solo, and no longer owns the V-tailed Bonanzas that took him to all four corners of the continental United States. But the retired telephone company engineer still takes offers from friends to go up in their planes.

“I’ll continue as long as my health permits,” said Hoffmire, who this year was awarded the FAA’s Wright Brothers Master Pilot Award for 50 years of safe flying.

Bill Voorhis, a Sussex County resident who will turn 93 in February, retired from his flight instructor job just four months ago. But he said his decision had more to do with money than health.

With fuel and insurance, he said, “it’s too damn expensive to me. I’ve been flying for 73 years. What am I going to do, go up and spend $50 to $60 just to do a couple of takeoffs?”

Miller, whose Bonanza is hangared at Dutchess County Airport, five miles from the Poughkeepsie, N.Y., home he’s lived in for the past 85 years, agreed that money is the biggest impediment to flying these days.

When it costs a minimum $20 just to practice his landings, Miller said, even he has taken to flying coach rather than piloting his Bonanza to California to visit his grandchildren.

Just like older drivers, aging pilots have long been a safety concern in the aviation world – at least on commercial flights.

The FAA requires airline pilots to retire at age 60. And insurance costs can rise dramatically for general aviation pilots still flying past 70.

Sloane, the octogenarian group official, said an 83-year-old pilot he knows in Washington saw his insurance premium jump 360 percent during the past five years to $4,500.

Sloane has been helping the national Aircraft Owners and Pilots Assn. gather information for a study on the safety records of 80-and-over pilots.

Of 125 pilots surveyed so far, he said, four aircraft incidents have been reported that could be considered age-related.

“That’s an incredible percentage,” he said. “So there’s very little reason for the increase in premiums that some of the insurance companies” are charging.