Kyrgyzstan national Aidana Baizieva, who was among the six people killed in the April 6 helicopter crash in Semenyih, was "actively participating" in the flight operations, the New Straits Times reported today.

Quoting a source, the report said data from the cockpit voice recorder (CVR) suggested that the AS365N2 Dauphin helicopter could have been operated by both Captain Clifford William Fournier and 25-year-old Baizieva.

The source said while there was nothing wrong in bringing Baizieva on board the flight, Fournier should not have allowed her to participate in flight operations.

Baizieva had been reportedly taking flying lessons from Fournier.

Meanwhile, the report also said while the passengers were "very chatty" as the chopper flew over Kuantan, the CVR data revealed that only silence were heard just before it crashed.

"Only the sound of their breathing was picked up by the CVR.

"Those on board spoke on various subjects irrelevant to the ongoing investigation... then there was a lull for several minutes right up to the crash.

"But let there not be any speculation on this, as their going quiet could be due to many reasons, including fatigue," the report quoted the source as saying.

The report also said investigators strongly believed that there was an explosion on board before the chopper went down.

Mystery has been shrouding the identity of Baizieva who was initially reported to be the co-pilot of the helicopter but was later identified as an operations assistant for Chempaka Aviation, of which Fournier owned.

The helicopter with the call sign 9M-1GB had six people on board when it crashed into a rubber smallholding in Kampung Sungai Pening, Semenyih at 4.55pm on April 6.

The other four who perished were Rompin MP Tan Sri Jamaluddin Jarjis; the Prime Minister's Chief of Staff, Datuk Azlin Alias; Kedah businessman Datuk Robert Tan, and Jamaluddin's bodyguard, Corporal Mohd Razkan Seran.