Christie went to the IRC in 1994. It was heard in the HCA in 1998. The Court held that the requirements of the particular position relied upon had to be inherent, ie involving permanent features of the position and not features that vary in time and place.
It found that “the age of sixty” could not be described as "permanent". The evidence showed that the retirement age for Qantas pilots had varied over time, including by the increase from fifty- five to sixty years during Captain Christie's service.
Christie lost because the High Court upheld the second leg of the Qantas argument which was the fact that 60 years of age was the age mandated in some other Convention countries.
As best as I can ascertain, Jetgo limits it's operations to Australia and there is no basis for an argument about what goes on in other Convention countries.
Post Christie, of course, the Age Discrimination Act was gazetted and age discrimination became unlawful removing the emotive arguments relating to a "disability".
If the argument is about insurers then they must be able to produce actuarial data to support the decision to refuse/load insurance at age 60.
Free hills have kindly published a digest on age discrimination at
australia
Kaz