Last night, Tigerair flight TT271 was forced to return to Sydney following the discovery of a supposed "threat" mid-flight.
The "written threat" was found on the flight from Sydney to Melbourne after departing, shortly after a 7.05pm departure, news.com.au reported.
The flight was greeted by police on the runway who ordered passengers to remain seated and keep their phones switched off.
A spokesperson for Tigerair Australia said in a statement that it was the captain's decision to ground the aircraft as a precautionary measure following the discovery:
"The captain made the decision to return to Sydney following an incident on-board. In line with standard procedures, the Australian Federal Police met the aircraft on arrival."
New South Wales Police confirmed officers were dispatched to meet the airplane at Sydney Airport. The officers from the Botany Bay Police were called to respond to a "threat" at about 8.30pm.
A spokesperson for the police replied to initial reports by Today that this was a possible bomb threat, but said this morning that the incident was more ambiguous: "This threat was more indirect in nature, and that it was a written threat found."
Meanwhile, passengers were left in the dark as to the developing incident.
Stevie Nicholson said his fellow passengers "been through hell and not one staff member to help sort out flights or even tell us what happened".
The affected passengers were given seats on another plane departing for Melbourne today at 9pm. Given the time of the incident and Sydney Airport's 11pm curfew, they were not able to be allocated a later flight causing significant delays.