Some Virgin Australia flights bound for Bali are stopping in Darwin to take on extra fuel in case Mount Agung erupts and the planes have to turn back.
Experts believe an eruption is imminent and Virgin says it's had to take precautionary measures.
"Some of our Bali bound flights will be making fuel stops in Darwin. This ensures that if an eruption occurs while the aircraft is en route, we will be able to get guests back to their originating port safely and quickly," it said in a travel alert.
Jetstar is closely monitoring the situation in Bali and so far flights are operating as scheduled.
Nearly 50,000 Indonesians have fled Bali's Mount Agung volcano region, with experts saying an eruption is imminent. It last erupted in 1963, killing about 1,100 people.
Despite these fears, Indonesian authorities say tourists continue to flock to Bali.
Arrivals at the international airport in Denpasar remain stable at about 50,000 to 60,000 per day.
"As long as the volcanic ashes don't have any impact on Bali's airport, it will not be closed," an airport spokesman has told the ABC.
Seven regional airports are on stand-by to receive aircraft if diversions are required.
Bali's primary visitor hubs are in the island's south, about 70km from Mount Agung.
Meanwhile, Australians have been told to check their travel insurance conditions if they intend to go to Bali.
But it's too late for anyone who doesn't already have insurance.
"Now that the status of the Bali volcano is a 'known event' ... it's too late to take out travel insurance to cover delays for the volcano," consumer group Choice warned.
The Australian government's Smart Traveller website continues to advise travellers to exercise a high degree of caution and monitor news reports.
Indonesian President Joko Widodo is expected to visit the area on Tuesday.