The man was restrained by flight stewards after he made threats to disrupt QF31 using mind power.
According to ABC reporter Nick Luchinelli, who was onboard the flight, it seemed the middle-aged man was either under the influence of drugs or alcohol or both.
He was suffering some sort of delusion and people sitting close to him said he was threatening to use the power of his mind to bring the flight down.
The stewards had to take the threat seriously so he had his arms and legs cuffed and remained that way for the rest of the flight.
Singaporean police boarded the flight after passengers disembarked.