According to a press release:
East Kimberly Region, Australia / Kassel, Germany, September 4, 2014 – CADS Survey, an Australian supplier of marine, pipeline, and civil surveying services, C.R.Kennedy & Co, a national importer and distributor of surveying equipment in Australia, and the German drone manufacturer Aibotix surveyed one of the world’s largest diamond mines with the Aibot X6 UAV (Unmanned Aerial Vehicle). Hereby they successfully executed a so called negative waypoint flight, 100 meters below the pilot’s position.