Grounded budget carrier Tiger Airways Australia on Friday looked unlikely to fly again until at least August 5, but vowed to meet new safety conditions and resume services in the "near future".
The Australian arm of Singapore's Tiger Airways was banned from flying earlier this month until at least August 1 over "serious and imminent" safety risks stemming from pilot training, fatigue management and other issues.
Tiger said Australia's Civil Aviation Safety Authority (CASA) had issued it with "a set of formal conditions" on Friday, some of which had to be met before flights could resume.
"As a consequence, Tiger Airways Australia will automatically refund all passengers booked to fly between 1 August 2011 and 4 August 2011," the carrier said in a statement.
"A further announcement, concerning flights scheduled to operate from 5 August 2011 and the re-commencement of sales, will be made at the appropriate time."
Tiger said it had been working constructively to address CASA's safety concerns and was "confident that it can comply with these conditions and expects to resume services in the near future".
CASA confirmed that formal conditions had been set for Tiger to resume flying relating to "pilot training, safety systems and overall management", following a month-long investigation into the grounded airline.
"The investigation's confirmed basically where we believed the problems would be," CASA spokesman Peter Gibson told AFP.
The probe was "in the final stages" he added, but said the "whole process isn't complete until we decide one way or another whether to lift the suspension".
"The conditions do not allow for a resumption of operations until CASA is satisfied Tiger is able to do so safely," the air safety agency said.
If Tiger agreed to meet all conditions, CASA said it would abandon court action, set for August 1, to have the flight ban extended but "in the meantime, Tiger remains suspended".