The Mi-8T helicopter took off from a base near the Vachkazhets volcano in the Kamchatka peninsula, the emergencies ministry said on Saturday.
That area of the peninsula is a popular tourist destination, famous for its rich landscapes and active volcanoes.
Officials say the helicopter disappeared from radar shortly after take off, adding that thick fog is hampering rescuers’ efforts. 
The helicopter, owned by Vityaz-Aero, was carrying out a trip to the volcano. Designed during the Soviet-era, the Mi-8 helicopter remains popular and widely used in Russia.
It disappeared from radar and crew members failed to make contact from around 16:15 (04:15 GMT), the governor of Kamchatka said. An emergencies ministry source told the state-owned news agency Tass that the crew did not report any difficulties before the disappearance.
Vladimir Solodov said it had 19 passengers and three crew members on board.
The aerial search continuing into the night but there was poor visibility.
Others have joined the search on foot, along the Bystraya River valley, along which the helicopter was supposed to move.
The mountainous Kamchatka peninsula – more than 6,000 km (3,730 miles) east of Moscow – is popular among tourists.
But there have been several air crashes over the years – two in just two months in 2021 alone.
