Moscow, Jun 8 (IANS/RIA Novosti): An inquiry into a helicopter crash in Russia has revealed that the accident which killed all the three aboard occurred because a drunk passenger was allowed to fly the chopper by its drunk pilot.

The accident took place on a December afternoon northwest of Moscow.

An analysis of the pilot's blood after the crash revealed that he had a blood alcohol level of 0.9 per mil, while the passengers had a level of 1.6 and 2.2 per mil.

The pilot was in the helicopter's front-left seat at the time of the crash, not the front-right seat that is fully equipped for flying the aircraft, suggesting it was being flown by the passenger, the Interstate Aviation Committee said in a report released Friday.

The US-made Robinson R44 crashed into a forest near the town of Solnechnogorsk Dec. 8 after clipping some tree tops and spinning out of control, the report said.

The pilot had obtained his license illegally by submitting forged medical documents. Neither the pilot nor the front-seat passenger was qualified to fly an R44 at night or in bad weather, the committee said.