The June 2 crash of a helicopter of Mountain Helicopters was caused by distraction by a passenger and the pilot’s failure to react effectively to an unfamiliar geographical situation, the Tourism Minister said on Thursday in its final report on the disaster.

The chopper had rammed into an electrical circuit and burst into flames in Sindhupalchok district, killing all four persons onboard.

In addition, pilot fatigue, lack of wire avoidance training and “no obstacles” marking on the power lines by the Nepal Electricity Authority have been blamed as contributing factors to the accident.

The report said that the main rotor of the 9N-AJP chopper struck the neutral wire after which it lost control and crashed in mountain terrain. Three Nepalis including Flight Captain Subek Shrestha, Dr Sandip Mahat and Sher Bahadur Karki and a Dutch doctor Jessica Wilford were killed in the mishap.

The helicopter was transporting rescue workers and relief supplies for earthquake victims in Dolakha when the accident happened.

Although the report has not clearly stated the nature of the distraction caused by the passenger, an official involved in the investigation said that a number of incidents occur due to the distraction as interruption breaks the thread of the procedure.

“In the Mountain Helicopters case, the investigation presumed that the pilot was distracted over such difficult and unfamiliar terrain as he was carrying on a conversation with the Dutch doctor,” said Pramod Nepal, member-secretary of the probe commission. The government had formed the probe commission headed by Tourism Joint Secretary Buddhi Sagar Lamichhane on June 3.

The probe commission has also identified pilot fatigue as one of the causes behind the crash. The report said that the pilot had been flying continuously for the past week without adequate rest. Safety experts say that pilot fatigue is responsible for 15-20 percent of fatal aviation accidents caused by human error.

Following the crash, the commission has issued interim safety recommendation to the Civil Aviation Authority of Nepal (Caan), Mountain Helicopters and the Nepal Electricity Authority to improve aviation safety so that such mistakes are not repeated.

Dinesh Kumar Thapaliya, secretary at the ministry, said that the government was serious about assuring aviation safety, and that the safety recommendations would be implemented with the utmost priority. He directed Caan and the other authorities concerned to take immediate corrective actions to enhance safety as per the recommendations of the commission.

Receiving the crash probe report, Tourism Minister Kripasur Sherpa urged the concerned stakeholders to work jointly to rebuild public confidence in air transportation. “Any lapses and negligence in air safety will not be tolerated,” he said.