A National Transportation Safety Board report regarding the Dec. 22, 2010, hard landing of a special light sport aircraft on Kauai once again raises questions regarding the legal gray area within which operators have been offering sightseeing tours under the guise of flight instruction.

Neither the pilot nor passenger in the Apollo Delta Jet AS-III aircraft was injured in the incident, one of several over a 14-month span involving so-called weight-shift control aircraft. Six people were killed in three separate weight-shift control aircraft crashes in Hawaii during that span.

In his accident account to the NTSB, pilot Ryan Mc­Anarney said he had problems controlling the aircraft’s wing about 45 minutes into his flight from Port Allen Airport and decided to make an emergency landing on a fairway at the Kukuiula Golf Course. McAnarney said the aircraft toppled to the left during the rollout portion of the landing.

A post-accident investigation found damage to a fabric nose cone that was "not consistent with impact damage from the accident." Photographs of the damage were forwarded to the aircraft’s manufacturer.

According to the NTSB report, released Monday, the manufacturer "ascribed the nose cone damage to repeated folding of the wing with the nose cone still installed" and concluded that "the nose cone damage adversely affected the functionality of the nose cone, and allowed ram air (dynamic air pressure produced by an aircraft’s motion) to enter and inflate the wings, which resulted in the pilot’s control problems."

McAnarney contracted his services to now-defunct Big Sky Kauai, which was owned by James Gaither.

Gaither and passenger Kim Buergel, a visitor from Spokane, Wash., were killed Feb. 15, 2011, when the weight-shift control aircraft Gaither was piloting crashed in waters off Kalaheo.

Federal Aviation Administration regulations prohibit the use of special light sport aircraft like those piloted by Gaither and McAnarney for revenue sightseeing flights. However, they can be used for flight instruction.

As the NTSB report notes: "Several operators in Hawaii, including (Big Sky Kauai) and the accident pilot, utilized (special light sport aircraft) to conduct introductory flights, which they termed ‘discovery’ flights. The flights were advertised and marketed as sightseeing flights, but the flight documentation referred to them as instructional flights."

The report cited text from Big Sky Kauai’s website promising, among other things, "powered hang glider tours of Kauai that rate better and safer than helicopter tours."

The report also includes statements from an FAA inspector who said that despite the "hundreds" of introductory flights given under the guise of flight instruction, there was no follow-up training or repeat students.

The inspector also reported that the operators "did not conduct ground school training and lacked the facilities to do so."