A partly constructed Avid MK-IV airplane sits in the driveway of Ed D’Antoni in Calgary, Alberta, in August 2007. D’Antoni is one of a growing number of pilots who build their own airplanes. (Photo courtesy of Ed D’Antoni)

The normally serene resort of Hilton Head Island, S.C., was witness to a horrific accident on March 15, when a jogger on the beach was struck and killed by a small airplane making an emergency landing after its engine failed. The plane was a four-seat Lancair IV-P — a sleek, high-performance single prop whose wingtips curl up toward the sky. It was also unusual in another way — it was built by its pilot, not in a factory.

The Hilton Head accident is one of several fatalities in the past several months involving so-called homebuilt aircraft. On April 3, Michael Cupaiole, a 58-year-old commercial pilot and flight instructor with more than 3,500 total hours in the cockpit, died when his homebuilt plane crashed into a lake just after takeoff in West Palm Beach, Fla. And then there is perhaps the most famous casualty of all, the 1997 death of singer John Denver, who plunged into the Pacific Ocean near Pacific Grove, Calif., while piloting a homebuilt.

Owners are passionate about their homebuilts. Some spend years fashioning each part. But most buy kits that include premade elements like the fuselage. However, to qualify as a homebuilt aircraft in the eyes of the Federal Aviation Administration, at least 51 percent of the plane must be constructed by the owner, not in a factory.

Homebuilts are almost always one-, two- or four-seaters; cost a fraction of a factory-built equivalent; and in most cases fly faster and are more maneuverable. After homebuilts first gained popularity in the 1980s and 1990s, their number in the U.S. has increased by about 1,000 each year for the past decade. There are now some 31,000 on the FAA’s registry, compared with about 240,000 factory-built private planes.

As the numbers grow, there are some who worry that homebuilts suffer significantly more crashes than their factory-built equivalents because they face an inspection regime that is too lax.

“It’s sort of a laissez-faire kind of thing,” says Bruce Landsberg, president of the Air Safety Foundation, which promotes safety in general aviation. “Pretty much anything goes.”

Statistics from the FAA and the Aircraft Owners and Pilots Association show that homebuilt planes suffer nearly five times more accidents per hour flown than noncommercial factory-built aircraft. Accidents involving homebuilts rose from 215 in 2005 to 264 in 2009. Fatalities jumped to 99 last year, from 78 in 2005.

While the numbers appear alarming, some supporters of homebuilt aircraft dispute their accuracy, arguing that the FAA estimates of hours flown are unreliable.

“The numbers don’t tell the whole story,” says Joe Gauthier, 70, a flight instructor, FAA-licensed inspector of homebuilt aircraft, and pilot, who has flown some 150 different homebuilt airplanes. “It’s not apples to apples.”

The Experimental Aircraft Association, the largest association of amateur builders, argues that a more appropriate measure is the accident rate as a percentage of the total fleet. In that light, only 0.19 percent of the amateur-built fleet was involved in fatal accidents in 2006 and 2007, compared with 0.32 percent in 2001 and 2002. Nevertheless, such rates are still higher than those of factory-built planes, which saw only 0.09 percent of its total aircraft involved in fatal accidents in 2006 and 2007.

“Not to disparage amateur-built planes, but our aircraft have to be approved by the FAA and go through a certification process that is quite thorough,” says Mark Miller, a spokesman for Piper Aircraft, one of the largest manufacturers of small airplanes.

Neither the FAA nor the National Transportation Safety Board, which investigates airplane accidents, has raised alarms about the risks of homebuilts. The still relatively low number of accidents has kept homebuilts off their radar screens. And the FAA’s normal channel for raising concerns about airplanes — issuing what are called airworthiness directives — does not apply to homebuilts.

“These amateur-built planes, because they’re not built to any standard, we can’t issue airworthiness directives for them,” says Les Dorr, a spokesman for the FAA.

Homebuilt enthusiasts seem happy to accept the odds. Some proponents draw a comparison to motorcycles. “People regard motorcycles as a bastion of freedom,” says Dick Knapinski, a spokesman for the Experimental Aircraft Association. “You accept responsibility for that freedom.”

Those bitten by the homebuilt bug are not likely to be dissuaded by statistics. Joe Gauthier took 17 years to build a Thorp T-18, an all-metal, two-seat prop with a sliding bubble canopy that gives it the look of a jet fighter. He explained that the delay was a result of his helping others build their planes. “My kids were little when I started, and I was a grandfather when I finished,” Gauthier jokes.

D’Antoni prepares to touch down in his completed homebuilt at Chestermere Kirkby Field near Chestermere, Alberta, in November 2008. (Photo courtesy of Ed D’Antoni)

Ed D’Antoni, 71, of Calgary, Alberta, is a pilot who got into homebuilding as a retirement pastime. “It was sort of fluke,” he says. “A friend had bought a kit, and I ended up joining. It was so much fun building and more fun flying, I sold my Cessna.”

Building your own plane is certainly one of the most affordable ways to enter aviation. The kit for a Van’s Aircraft RV-7, a sleek single prop that is a top seller, costs about $20,000. The cost to completion is between $50,000 and $100,000, depending on the options, and the airplane would fly circles around a similarly sized Cessna Skycatcher, which retails for $112,000. It would also be faster and more maneuverable than the slightly larger Cessna Skyhawk, one of the most popular entry-level factory-built airplanes, which costs $270,000.

Homebuilt planes are technically categorized as experimental aircraft, which also includes airplanes meant for racing and for research and development. The FAA created the category because the regular certification procedures were considered too cumbersome.

Homebuilts do go through an FAA-mandated inspection process and have to document each step of construction to the satisfaction of an inspector. But the process is less rigorous than the one for factory-built aircraft. Inspectors see their role more as trusted advisers to builders, who have already sunk in countless hours and will be putting their own necks on the line in flight.

Gauthier says he rarely finds any serious mistakes during inspections. He credits the success of homebuilt planes to the growing quality of the kits and to the community of amateur builders, who are quick to share their experience. “Most of the problems are with individuals who decided they didn’t need any advice,” he says.

Yet this more relaxed inspection regime means that while some amateur-built planes may be better than their factory-built competitors, others might not. With homebuilts, says Landsberg, the Air Safety Foundation president, “you never know what you’re going to get.”

But even Landsberg argues that it is not fair to judge homebuilt aviation by a few freak accidents that take the lives of bystanders, like the one that killed the jogger in Hilton Head. “That was a 1-in-10 million kind of occurrence,” he says. “In an average year, you can count the number of injured on the ground on one hand.”