A pax report of the incident from this SMH article, some seeming similarities to the recent AA incident LAX-HNL:
Former AFL player Andrew Leoncelli was sitting in business class, several seats away from the cockpit, when the incident unfolded. He described seeing a man carrying a large black cylindrical object which looked like [a] speaker, which appeared to have an on/off button and a charging port.
Mr Leoncelli said the passenger was "screaming" at the flight attendant saying "I need to see the captain" and walking to the front of the plane during take-off.
The passenger reportedly said: '"I've got a bomb and I'm going to f--king blow the plane up," he said.
The flight attendant yelled at the man to sit down and when he refused she called out for help.
Mr Leoncelli said at this point he unbuckled his seatbelt and went to confront the man who he said appeared agitated and kept repeating his threat.
"Literally he was eyeball to eyeball with me saying he was going to blow the plane up."
"He looked like a lunatic," he said.
"For some reason he lost his nerve and he ran... and he headed towards the back of the plane," he said.
"I hadn't done anything to him except confront him," he said.
Mr Leoncelli then said others on the plane were able to overpower the man.
Two young Australian men who were passengers on the flight "went to work on him and got him in the shackles good and proper, they were the heroes", said Mr Leoncelli. A picture taken by another passenger and posted to Twitter showed a man lying flat on his stomach on the floor of the plane with his hands bound behind his back with plastic handcuffs.
Malaysia Airlines flight turned back to Melbourne after 'threatening' passenger tried to enter cockpit
Twitter picture here:
https://twitter.com/saroki19/status/869954554481131520