A helicopter with at least 21 people on board has gone missing in the far north of Russia. The Mi-6 helicopter took off from the Polar city of Norilsk on Wednesday at 10.00 UTC, but had failed to arrive at its destination three hours later. It is thought to have gone missing near the island of Dikson, in the Taymyr region. Another Mi-6 helicopter was initially sent out to search for the missing...