Fresh questions are being asked about the preparations that Qantas made before grounding its entire fleet late last month.
Two couriers say they were booked to deliver lock-out notices to Qantas employees several days before the airline stopped operations on 29 October, stranding an estimated 70,000 passengers worldwide.
Chief executive Alan Joyce again rejected the claims as the dispute heads to arbitration after talks with three unions broke down before a deadline of midnight on Monday.
Fair Work Australia was ordered to step in by the federal government on 30 October and will now has to settle the dispute.
Qantas also denies claims it used stonewalling tactics but the unions say the negotiations were not genuine and open.
Mr Joyce says Qantas was committed to seeking a peace deal.
Earlier, he said Qantas was losing $A15 million per week due to months of strikes and industrial action by the three unions.