New details about the alleged plot emerged as Australian pilots called for photo identification to be reintroduced for the issuing of all domestic plane tickets and for all airport employees, including those checking in hand luggage, to go through thorough security screening.
Abdul Merhi, 50, Khaled Merhi's brother, who was also arrested, walked from police custody without charge on Tuesday night.
Although the men have not formally been charged, legally they can remain in custody for a prolonged period of time under special terrorism powers.
Counter-terrorism police have conducted several recent raids, heightening tensions in a country that has had very few domestic attacks.
Sources have revealed the group were in contact with Islamic extremists in Syria and Iraq, while one of them had undergone training in the aviation industry.
The move prompted lengthy passenger ques that snaked outside terminal doors as travellers were urged to arrive hours before their flights.
"There's a lot of stress associated there, and not knowing, and he was shocked that he was being questioned", Kheir said.
Prime minister Malcolm Turnbull said today that the threat level "will be restored to the level it was a week ago" on advice from the director-general of ASIO.
Investigators have said the alleged plan most likely involved detonating an improvised explosive device.
"The Etihad Airways aviation security (AVSEC) team is assisting the Australian Federal Police (AFP) with its investigation and the matter is ongoing", an Etihad spokesperson said in a statement to Khaleej Times.
Increased airport security measures introduced after the arrests have caused delays for some air transport operators.
Reports suggest the cell had planned to smuggle the homemade device on board using a kitchen meat mincer.
Australia's national terror threat level remains at "probable" - the third level on a scale of five. "We want to review all the information police had and what basis they had to do what they did".
Mr Turnbull said the suspected plot was "advanced" and driven by "an Islamist extremist motivation".
Etihad Airways has confirmed it is helping Australian authorities with the investigation after the arrests came following a tip-off from foreign intelligence services.