Two brothers behind a failed terror plot to plant a bomb on an international flight from Sydney have been handed lengthy jail terms of 40 and 36 years.

Khayat brothers have been sentenced to 40 years and 36 years in prison

Khayat brothers have been sentenced to 40 years and 36 years in prison They were convicted over a plot to bomb an Etihad flight to Abu Dhabi in July 2017

They were convicted over a plot to bomb an Etihad flight to Abu Dhabi in July 2017 Judge said they had "jeopardised" the community's sense of safety

Khaled Khayat, 51, and Mahmoud Khayat, 34, planned to bring down an Etihad Airways flight to Abu Dhabi with the device hidden inside a meat grinder in July 2017.

The bomb was placed in the luggage of a third brother, Amer, who was to unwittingly carry it onto the plane, but the plan was aborted at Sydney Airport.

The brothers then planned a separate attack using a poisonous gas.

This year, two juries found them guilty of conspiring to plan a terrorist act.

Justice Christine Adamson today said even though nobody was injured or died as a result of the plan, the brothers succeeded in creating terror in the minds of the general public.

"By their conduct they have jeopardised the sense of safety members of the community are entitled to expect," she said.

"The conspiracy plainly envisaged that a large number of people would have been killed ... no-one would have survived ... no-one would have had time to say goodbye."

Justice Adamson sentenced Khaled Khayat to 40 years in prison with a non-parole period of 30 years.

Mahmoud Khayat was handed a jail term of 36 years with a non-parole period of 27 years.

Amer Khayat spent two and a half years in a notorious Beirut prison after he was arrested overseas. ( ABC News: Mridula Amin )

The court previously heard Khaled Khayat was motivated to support militant groups fighting the Syrian regime.

The plot also involved another brother, Tarek Khayat, a senior member of Islamic State overseas, and a man known as "the controller".

In the months leading up to the attack, components of the explosive were posted from Turkey to Australia.

Tarek and the controller used an encrypted mobile phone app to send instructions and videos about how to assemble the bomb.

It was put together in July 2017 in one of the men's garages.

At Sydney Airport, Amer Khayat, who had been asked to carry gifts for his family overseas, was told to repack his luggage by an employee due to weight allowances.

Justice Adamson found the "compelling inference" of the evidence was that Khaled Khayat removed the bomb because he thought the risk of detection was too great.

The plot was uncovered two weeks later, thanks in part to a tip-off from Israeli authorities.

Khaled Khayat argued at trial he was simply pretending to cooperate with the plan to prevent Tarek and the controller from finding a more willing person to carry it out.

Mahmoud Khayat claimed to be "an innocent helper" who performed acts through a sense of family "obligation".

Police search bins at a property on Sproule Street in Lakemba in 2017. ( ABC News: Jessica Kidd )

Justice Adamson found Khaled Khayat was more culpable than his younger brother, but said Mahmoud's superior English language skills and knowledge of technology helped advance the plan.

She said Tarek and the controller were the "guiding minds" of the conspiracy, while the Sydney-based duo played "significant" roles to carry it out in Australia.

Tarek Khayat has been sentenced overseas to the death penalty, but the court has heard he has been given a reprieve because he has lung cancer and may die "any minute".

Amer Khayat, who had been estranged from his brothers, spent two and a half years in a notorious Beirut prison after he was arrested overseas.

He was cleared of any involvement by a military court in September.

Last week, he said he still loved his brothers even though they tried to set him up because they are his "blood".