Sunsfish, determining the "cost" of providing a service for a given route is, at best, problematic given the mix of fixed/variable and direct/indirect costs incurred in operating an airline.
If an airline can demonstrate that its revenue from a given route is exceeding that route's variable costs (in other words, the route is making a contribution towards the airline's fixed costs), I suspect that the ACCC will have some difficulty in arguing the existence of predatory pricing.