The summer of 1971 was hot and dry. This circumstance ensured that the plan would be exceeded and promised large earnings for Ivan Kopyriv's geological exploration expedition, which was located in the area of the Tunguska village of Erbogachen. Upon encountering a layer of permafrost, master Yelfimov, contrary to fire safety regulations, ordered the permafrost to be thawed with bonfires. However, the dry and gusty wind did its job: the resulting fire spread with catastrophic speed to the continuous forest areas, and the situation spiraled out of control.