Some 17 months after a light sport aircraft crash claimed the lives of two people on Kauai, the National Transportation Safety Board has yet to release its determination on the cause of the crash.

On Feb. 15, 2011, pilot Jim Gaither of Big Sky Kauai and passenger Kim Buergel of Spokane, Wash., were killed when the powered glider Gaither was piloting crashed into the ocean off Kalaheo. The incident was one of three fatal crashes during a 14-month period that drew attention to a regulatory loophole allowing lightweight, two-person aircraft to be exempted from strict commercial air tour safety standards.

So-called weight shift aircraft cannot legally be used for tours. However, they can be used for flight instruction purposes. Some local companies thus advertise commercial flights with a licensed pilot as flight training.

The online NTSB docket for the incident, last updated on March 29, contains the initial accident report, individual witness accounts, equipment specifications and operation instruction, a toxicology report, notes from an engine examination, photos and other materials but no official determination on the cause of the crash.

According to the accident report, the glider, an Edge XT-912-L light sport aircraft, was owned by Christopher Sadler and operated by Gaither, doing business as Big Sky Kauai LLC. The purpose of the flight was listed as "instructional." (Patty Hanson, a Washington state resident who was with Buergel, previously said she and Buergel believed the flight was a tour and not instructional in nature.)

Two of the five witness accounts included in the archive indicated possible engine trouble.

A kayaker who was in the area at the time of the accident told investigator James Struhsaker that he heard the engine sputter, then restart, the aircraft eventually rising about 100 to 200 feet.

"Suddenly the engine (went) silent, and the nose of the aircraft headed straight down towards the ocean," stated Struhsaker’s record of the interview.

Another witness provided a similar account of the aircraft dropping toward the ocean, as if to land, rising swiftly and then plunging nose first into the water.

A fellow light sport aircraft operator offered a theory about the crash based on a similar experience. Denise Sanders of Oahu said Gaither was likely executing a move called "shooting the cliff," in which a pilot flies over a cliff and above the ocean, giving the passenger a feeling of "the bottom dropping out."

Sanders theorized that the passenger might have "bumped the (starting carburetor) on" at this point, causing the engine to sputter, and that the pilot unsuccessfully tried to regain altitude before the aircraft turned left and downward.

An inspection of the aircraft performed on March 8 and 9, 2011, concluded that "nothing was found to preclude normal operation of this engine prior to the impact and salt water contamination."

A forensic toxicology report on Gaither turned up negative for drugs, carbon monoxide and cyanide. Ethanol was detected in Gaither’s blood and heart but not in his urine or brain. The report noted that "the ethanol found in this case is from sources other than ingestion."