I read today that pilots of aircraft from the Americas flying into Sydney now need to make a mandatory passenger health report before they can receive landing clearance due to the recent swine flu epidemic.
I am not sure what the process would be if the report eluded to a potential case of swine flu onboard, perhaps quarantine at Kingsford Smith or diversion to another airport.
More of that report on the asiaone health website here:
http://health.asiaone.com/Health/News/Story/A1Story20090427-137839.html