You'd think that was quick, ... but generally this kind of thing would be done from a crop duster airframe flying at an industry standard 70m/sec (252 km/hr).
I'm guessing the local Perth geophysical survey companies that routinely fly magnetics and radiometrics were all fully engaged flying pre booked contract work .. so they dragged in a couple of white transit vans and fitted them out to get the job done.
I'm guessing the local Perth geophysical survey companies that routinely fly magnetics and radiometrics were all fully engaged flying pre booked contract work .. so they dragged in a couple of white transit vans and fitted them out to get the job done.