Pilots differ about the cause of three fatal crashes of two-seat aircraft in Hawaii in the past 14 months, but the Federal Aviation Administration should review its rules governing the nature of the flights.

Current rules prohibit the aircraft from being used for commercial air tours — so companies instead merely refer to the tourists as student pilots.

Three pilots and their single passengers — Kathryn Moran of Kailua-Kona, Kimberly Buergel of Spokane, Wash., and Ray Foreman of Vista, Calif. — died in the crashes of a small, powered gliders known as trikes. At least two of the riders — Moran and Buergel — were in it for the thrill, not as student pilots, according to those close to them.

Jim Struhsaker, an investigator for the National Transportation Safety Board, said light sport aircraft operators usually have passengers sign a form stating that the flight is for "introductory flight training."

A manufacturer has posted online a form waiving liability for injury or death, stating that "ultralight trike flying is an extremely dangerous sport."

Indeed, Patty Hanson, Buergel’s partner, told the Star-Advertiser’s Gary T. Kubota, "I signed a waiver but I wouldn’t know what’s on it."

Phil Olsen, a retired flight instructor at Hono­lulu Community College, said the FAA "should exercise more control" over the trike activity. The agency’s current rules, written in 2004 as trikes came on the market, are more lax than those covering large aircraft, requiring pilots to have taken at least 150 hours of flight time in order to fly with a student, compared with 250 hours for commercial pilots.

Since 2006, when a significant number of "special light-sport" vehicles began entering the air, they have been involved in 133 accidents, about triple the rate of single-engine piston planes, according to commercial pilot David J. Kenny, safety database manager for the Aircraft Owners and Pilots Association. He added that 38 percent of those accidents occurred on instructional flights, compared with 14 percent of accidents of larger planes.

Kenny said trikes are more likely to be in accidents just as motorcycles are more vulnerable than automobiles because the weight-shift aircraft are "entertainment machines."

Some in the industry, though, defend the safety of ultralight craft and many of their operators, but bring up the factors of pilot judgment and error in the crashes.

The website of Kauai Aerosports, involved in last week’s trike crash off the Na Pali Coast State Park that killed Foreman and company owner-pilot Steve Sprague, urges people to "come join us for an adventure of a lifetime and see Kauai in a way no other venue can."

In smaller type, it mentions "Introductory Flight Lessons over the beautiful canyons, rivers, waterfalls and coastline of Kauai."

Technically, that complies with the law. But given these high-profile accidents and the increase in trikes, the FAA should reassess and consider changing the rules to require that flight lessons be less of an adventure and more of an instructive session, with safety being paramount.