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Tech Stop / Transit Aircraft
A landing charge of $5.89 per tonne MTOW will apply.
A minimum charge of $394 will apply.
Other charges will apply depending on aircraft size, hours of operation and services provided.
In your operation, I would envisage that you were considered Transit, and yes I agree it to be erroneous
Therefore, Cairns Airport is charging you for airspace, something I would think they have no authority to do. Albeit ASA may have contracted them to manage airspace charges (just throwing it up there) but for some reason called a brain, i highly doubt it.