An 'air rage thug' died on a flight after fellow passengers overpowered him as he threatened to 'break into the cockpit.'

The man, 37, 'rampaged through the plane threatening passengers with scissors' and sought to 'break into the flight deck,' reports say.

Vladimir E. was pinned down by fellow passengers and 'tied up with plastic clamps' by the crew, according to accounts of the incident on a Russian plane flying from Moscow to Omsk.

When the man 'calmed down,' he was untied, but immediately lost consciousness, according to witnesses.

A report said: 'There was nothing that could be done to help him.'

The passenger was declared dead by paramedics when the plane landed in Omsk, Siberia after a three-hour flight.

'Medics confirmed the death on arrival at the terminal,' said a regional health ministry spokesman.

A criminal case has been opened into the man's death amid suspicion of 'causing death by negligence.' Crew and passengers are being interrogated.

The Russian transport investigative committee said: 'Investigators are currently establishing all the circumstances of the incident.'

The airline involved and the passenger's name have not been disclosed.

Expert Vasily Shurov said: 'We need to await the results of the brawler's autopsy, as it's truly unclear what happened on the Moscow-Omsk flight.

'There could be many possible theories. First, we need to consider his extreme aggression and attempts to kill others.

'He may have suffered a cerebrovascular accident or overindulged in alcohol. Second, how the brawler was restrained is important.

'Perhaps there was a serious fight, and he sustained specific injuries. And, of course, the very fact that he was restrained.

'This could have caused a circulatory disorder, which then led to a blood clot.'