The type of lightweight, two-person aircraft involved in three fatal crashes in Hawaii in the past 14 months appears to operate in a regulatory loophole that exempts it from strict commercial air tour safety standards.

Federal Aviation Administration rules authorize weight-shift control aircraft to carry student pilots for flight instruction but bar them from carrying commercial air tour passengers.

Yet friends of victims in two recent fatal crashes told the Star-Advertiser that they viewed the flights as tour excursions, not flight training. Two of the three passengers who died were from the mainland, and the third was a Big Island resident whose aim was a scenic adventure, not flight training, the victim’s friend said in an interview.

"It was just a thrill ride. It was just something for us to do on this island," said Cindy Warner, whose friend Kathryn Moran of Kailua-Kona was killed along with the pilot in a crash in Kealakekua Bay on April 21, 2010.

Warner said before she and Moran paid for their rides, no one told them that such aircraft have lower safety requirements than commercial aircraft and that weight-shift aircraft are barred from conducting tours.

National Transportation Safety Board investigator Jim Struhsaker, who is investigating Tuesday’s fatal crash off Kauai that killed the pilot and a California visitor, said the possibility that some owners of weight-shift aircraft conduct air tours under the guise of flight training is a "soft spot in the whole industry."

Struhsaker said light sport aircraft operators usually have passengers sign a form saying the ride is for "introductory flight training."

"Technically it’s legal," he said, "but most (clients) don’t follow up and get pilot certificates."

Ryan McAnarney, who was an independent weight-shift pilot with Big Sky Kauai, said every passenger received instruction on flying and also viewed a safety and flying instructional video. Big Sky Hawaii owner Jim Gaither and a passenger died in a crash on Feb. 15.

McAnarney said the purpose of the business was to get clients interested in flying.

"Jim had a passion for flying," McAnarney said.

All three fatal Hawaii crashes are under investigation by the NTSB. No final determination of cause for any of the incidents has been announced.

The type of aircraft involved in the three fatal crashes is classified as "weight-shift control aircraft" but is more commonly known as powered gliders or air trikes. Such craft often look like a hang glider with a small fuselage slung underneath, with two open cockpit seats and a rear-facing propeller.

David J. Kenny, safety database manager for the Aircraft Owners and Pilots Association, said weight-shift aircraft have virtually no cabin structure to protect occupants. He said the safety difference between a powered glider and a tour helicopter or airplane is analogous to that between a motorcycle and a car.

"Motorcycle accidents are more likely to cause injury than automobile accidents," he said. "These weight-shift aircraft are entertainment machines … flown purely for pleasure and excitement."

Phil Olsen, a retired flight instructor at Honolulu Community College, said powered gliders are not designed to sustain aerobatic maneuvers. He said he feels the government should increase its oversight of such businesses.

"Clearly, the FAA should exercise more control," Olsen said.

The FAA established rules in 2004 to address the rapidly growing segment of low-cost "light sport aircraft," which includes powered gliders as well as small fixed-wing aircraft and craft of other designs.

FAA safety standards for weight-shift control aircraft are considerably less than for commercial aircraft such as airliners and tour helicopters.

A weight-shift pilot instructor who flies with a student must have a minimum of 150 hours of flight time; a commercial pilot’s license requires a minimum of 250 hours of flight time.

Weight-shift pilots are required to fly 1,000 feet above populated areas but have no minimum altitude restriction in unpopulated areas. Pilots flying tour airplanes and helicopters in Hawaii are required to maintain a distance of 1,500 feet from the nearest land, including vertical surfaces such as cliffs and mountains.

A weight-shift aircraft mechanic is required to complete 120 hours of instruction for airplanes and 104 hours of instruction for power parachutes and weight-shift control aircraft, FAA spokesman Ian Gregor said.

A mechanic who works on a tour aircraft requires FAA certification for that specific type of craft. The mechanic must have at least 18 months of experience with the procedures, materials and equipment generally used in building and maintaining airframes and power plants of the particular aircraft.

Though FAA rules limit passengers on weight-shift aircraft to student pilots, some websites for the companies appear to emphasize fun over instruction.

"Come join us for an adventure of a lifetime and see Kauai in a way no other venue can," says the website for Kauai Aerosports, which was involved in the crash that killed two people Tuesday off Kauai’s Na Pali Coast State Park.

In smaller type the website says, "Kauai Aerosports offers introductory flight lessons over the beautiful canyons, rivers, waterfalls and coastline of Kauai."

Close friends of victims in two of the fatal accidents said they thought they were paying for a thrill ride and tour and were unaware that weight-shift aircraft could not fly commercial tours.

"I didn’t sign anything to become a flier," said Warner, whose friend Moran died in the 2010 crash. "She wasn’t going to become a flier or anything. … She wanted to do something that was super-fun."

Moran was celebrating her 37th birthday when she went on a flight with pilot Tedd Robert Hecklin of Tedd’s Flying Adventure of Kailua-Kona. A witness at the time said the aircraft was making a turn when it flipped over — its wings folding like a butterfly landing on a flower — and plunged into Kealakekua Bay.

Representatives of Tedd’s Flying Adventure or relatives of Hecklin could not be reached for comment.

Kim Buergel of Spokane, Wash., was killed Feb. 15 when the powered glider she was riding with pilot Jim Gaither of Big Sky Kauai crashed in the ocean off Kalaheo. A witness told police the aircraft was flying at an altitude of 150 feet when it dived into the ocean.

A friend who was traveling with Buergel also said they thought they were taking a tour on a thrill craft and were unaware that such aircraft could not operate tours.

Patty Hanson, a Washington state resident, said neither she nor Buergel intended to become weight-shift pilots. "It was just something fun to do on our trip," she said. "I signed a waiver, but I wouldn’t know what’s on it."

In Tuesday’s incident a weight-shift aircraft operated by Kauai Aerosports crashed into the ocean, killing pilot Steve Sprague and passenger Ray Foreman, 53, of Vista, Calif.

The Star-Advertiser was not able to interview anyone close to Foreman as to whether he took the flight as a student pilot or air-tour passenger.

An eyewitness saw the aircraft making a sharp turn within 60 feet of a cliff off Honopu, then heard a sound like a rifle shot and saw the aircraft lose control.

Of the six crashes involving weight-shift aircraft in Hawaii since 2010, three resulted in a total of six fatalities, while a fourth incident caused serious injuries to the pilot and passenger, according to the FAA database.

Five of the six accidents occurred on Kauai.

Nationwide about 18 percent of general aviation accidents involve a fatality, but the fatality rate for light sport aircraft was 26 percent in 2010, said Ron Wantajja, an independent aviation accident analyst.

FAA spokesman Gregor said his agency has taken steps in response to the crashes.

Gregor said the FAA, following the Feb. 15 crash, arranged a safety meeting in early March at Lihue Airport that included almost all the light sport operators in Hawaii, the NTSB and aircraft manufacturers.

"The FAA discussed concerns with introductory instruction flights taking place in areas in which air tour aircraft operate, and potentially unsafe flying maneuvers," Gregor said.

He said most light sport aircraft operators indicated a willingness to work together to develop an operational handbook, which would include best safety practices, safe altitudes and suggested areas of operation.

"This would be an effort among the LSA operators and not run or dictated by the FAA," Gregor said.

But Warner, whose friend died in the 2010 Kealakekua crash, wants stronger oversight.

"That is so wrong," Warner said. "Something definitely needs to be done."