A MAGISTRATE has told a Melbourne University honours graduate, who had to be handcuffed and then bound to his seat by crew during a flight from Malaysia, that he had behaved like a terrorist.

Khairulddin Mohammad Yahya swore loudly at the inflight supervisor and poked him in the chest before the captain left the cockpit to deal with him.

Melbourne Magistrates Court yesterday heard that Yahya, 22, swore loudly at the supervisor while a passenger told his mother to shut him up because he was frightening people. Prosecutor Aman Dhillon told the court that Yahya repeatedly left his economy seat and sat next to his mother in business class after her requests for his upgrade were refused.

Mr Dhillon said hours after the Malyasian Airlines flight left Kuala Lumpur on July 22 last year, he was seen in the vacant seat next to his mother. He complied with a request to return to his seat but, soon after, reappeared whereupon the supervisor detected alcohol on him.

Mr Dhillon said that several hours before landing Yahya again sat in business where he called the supervisor a ''motherf-----'' and to ''f--- all of you''.

The captain, who noticed Yahya slurred his words and smelt of alcohol, asked his mother to tell him to return to his seat and stop harassing the crew.

Yahya complied, but later returned four times to business class before he was handcuffed in his seat and then was restrained with his ankles tied with tape.

Mr Dhillon said his mother tried to loosen the handcuffs and lead Yahya to the toilet, then she began screaming hysterically and fell to the floor as he shouted threats.

When the plane landed, he co-operated with police. Mr Dhillon said some crew felt threatened and some passengers appeared stressed and frightened. One was crying.

Defence lawyer Anna Balmer said Yahya was ''somewhat intoxicated'' but wanted to sit with his mother who had medical conditions that included chronic anxiety, neurosis and depression.

Ms Balmer said Yahya, a chemical engineer, acted uncharacteristically with poor judgment and behaviour, and that a conviction could jeopardise his visa status and work.

Senior magistrate Dan Muling told Yahya, who pleaded guilty to disorderly behaviour on an aircraft, that he was out of control. ''It's like you're a terrorist on a plane,'' Mr Muling said.

Yahya was convicted and fined $1500.