A Victorian mother who made a "stupid" bomb threat before boarding a flight from Hobart to Melbourne has been slapped with an $800 fine.

Richelle Marissa Penny, 42, told check-in staff she had a bomb in her baggage before boarding the Virgin Australia flight on December 14.

She was removed from the flight and the plane was delayed for an hour.

On Thursday she pleaded guilty in Hobart Magistrates Court to threatening to commit an act of unlawful interference with aviation.

Penny, from Knoxfield in Victoria, was repeating a joke she heard from a taxi driver several days before the flight, the court heard.

"You got this stupid joke from your stupid taxi driver and repeated it without thinking," Hobart magistrate Michael Daly said.

Ms Penny, who was in Tasmania for her grandmother's birthday, was very remorseful and had apologised to Virgin Australia.

She suffers from medical conditions that make her prone to impulsivity.

Mr Daly said Penny's situation was different to someone who would make a comment to "put the wind up fellow travellers".