Qantas' low-cost subsidiary Jetstar on Thursday resumed flights to and from the Indonesian holiday island of Bali, but rival Virgin Australia will delay its services due to volcanic ash plumes.
"We've determined it's safe to resume services," Xinhua news agency quoted Jetstar as saying in a statement.
Volcanic ash can severely affect the aircraft, choking its jet engines and destroying bodywork.
Virgin Australia flights to Denpasar on Thursday were delayed, the company said in a statement.
Unfavourable winds this week pushed ash from Mount Raung, 150 km west of Bali, back towards Denpasar, forcing the closure of its airport.
Aviation expert Geoff Thomas told local broadcaster Channel Seven that winds were now blowing the ash cloud away from Bali, but the threat may not be over if the volcano continues to erupt.
"It shows no sign of abating and it really depends on the wind conditions, and so we could have the same situation in 24 or 48 hours."
Earlier in July, thousands of Australians were stranded in Bali for extended periods while Virgin Australia and Jetstar flights were severely disrupted due to the ash cloud from Mount Raung.