Originally Posted by
teemuflyer
Was it with AA? If so, no issue aside for a kind of wild rerouting. As AA is a US carrier, it would not be considered cabotage. And in the case of the OP, if somehow they "allowed" JFK-LHR-AUS, and the first segment was on AA, there shouldn't be a issue from a cabotage perspective.
Hola! During the time of the volcan in 2010 I was ticketed on UA LHR to IAD. The delays were stretching for many days and with a polite insistence it was possible to reroute UE to EEUU via NRT or HKG. But that is different from the example of OP.