According to the Transport Ministry’s interim report on the tragedy, released today, the helicopter was airworthy to fly, while the pilot was experienced and properly licensed for the operation.

The nine-page report noted the helicopter was not equipped with flight and voice recorders.

While the report praised the search and rescue (SAR) efforts, it acknowledged it was filled with challenges.

For one, no distress calls were made by the pilot and no distress signal from the helicopter was emitted.

The size of the search area to the number of men and assets available for the SAR mission also presented another obstacle.

The Batang Lupar river, the report stated, covers 40km and averages 3-4km wide.

It is perpetually muddy, due to logging activities carried out upstream. There are also issues of strong currents, making diving activities hazardous, the report said.

The SAR team had to also look out for crocodiles as the river is home to a large population of crocodiles. They posed an ever present danger to those operating in its environment.

A couple of safety recommendations to prevent such accidents from recurring were also made by the ministry.

The first is the review of Air Traffic Services emergency response for overdue aircraft. An aircraft is considered overdue when neither communications or radar signals can be established.

Secondly, the Civil Aviation Department should improve the decision-making process when flying in the rain or in the vicinity of a thunderstorm.

On May 5, the Eurocopter AS350, which left Betong for Kuching, crashed near Sungai Batang Lupar, Sebuyau, killing all six on board.

The victims were Noriah Kasnon, deputy plantation industries and commodities minister; her husband Asmuni Abdullah; the ministry’s secretary-general Dr Sundaran Annamalai; Kuala Kangsar MP Datuk Wan Mohammad Khai-ril Anuar Wan Ahmad; Noriah’s bodyguard Ahmad Sobri Harun and the pilot, Capt Rudolf Rex Ragas.