Have you ever returned home after an outing in the geomobile, only to find that it's covered in mud, dust, flies, salt, etc?
An aircraft in flight is also subject to the elements in the same respect, and the aircraft that fly out of RAAF Base Edinburgh even more so due to their role as a maritime patrol aircraft, accumulating loads of salt as they fly close to the ocean surface while searching for submarines, illegal fishing vessels and beleaguered British sailors.
The location on the airfield near to the given coordinates is an aircraft wash point, somewhere the aircraft can go to hose down all the salt and other unwanted coatings prior to its homecoming. If you're lucky enough to be driving past while finding this cache, you may even see an Orion in the 'birdbath' after returning from a flight!
The cache is NOT at the given coordinates, but is less than a kilometre away. To get the coordinates you will have to find the solution in the pictures below.
*** FTF honours go to: howie_sf ***