This is stated in the message of the Investigative Committee.

Investigators found that the Su-30 crew stopped communicating due to the fact that the test pilots were in an unconscious state.

“In this regard, the investigation is checking the version of a malfunction of the onboard oxygen equipment system, as a result of which both pilots could lose control over its control,” the UK said.

The Su-30 crashed during a test flight on 23 October.

When the plane crashed, two pilots died, there were no casualties among the population.

The investigation opened a criminal case.