Qantas says it's hopeful of reaching a compromise before midnight in fraught contract talks with staff unions that triggered the shock grounding of its entire global fleet.
Qantas and unions representing pilots, engineers and ground staff were given 21 days to resolve their protracted dispute by the workplace umpire last month as part of orders banning all industrial action at the airline.
The deadline expires at midnight Monday and if talks are not extended by mutual agreement and they remain at an impasse all parties will be forced into arbitration.
Tony Sheldon, from the Transport Workers' Union (TWU), said little progress had been made in the three weeks since Fair Work Australia (FWA) ordered Qantas to lift the grounding of its fleet and unions to stop striking.
Sheldon said the latest offer made by Qantas was less than what had been on the table before the FWA hearing and accused the carrier of trying to force the matter to arbitration.
"The company has been extremely frustrating through the last seven months and even more frustrating in the last three weeks," Sheldon said.
But Qantas said Sheldon was "scaremongering" and insisted that it had been negotiating in good faith throughout the weekend hoping to reach a deal.
"Qantas has been very much committed to those negotiations and we remain hopeful that we can get a settlement today," Qantas spokeswoman Olivia Wirth told ABC Radio.
"The day can finish at midnight. We are very much committed to those negotiations and we'll see how the day transpires," she added.
Unions are angry about Qantas's plans to restructure its international business in Asia and want guarantees on wages and conditions and job security - demands the airline says are impossible to meet.
Wirth said there had been "concessions made by both sides" but she would not comment on Sheldon's claims that Qantas preferred arbitration.
"Arbitration is obviously one vehicle available to both parties at the negotiating table," she said.
"Qantas does believe that any decision made by the arbitrators is binding. That is the umpire's decision. We will stand by that and we would expect the unions to also agree to that."
The TWU has requested another 21 days to see if an agreement can be reached. Wirth said a decision would be made later Monday by the negotiating team on whether to extend the talks.