Ahead of the article on drones and UAVs in mineral exploration and surveying (International Mining, April issue), details have emerged of a near-miss between an Ayres S2R aircraft flying crop spraying on a property about 37 km south-southwest of Horsham aerodrome, Victoria, Australia and a UAV flying over the Iluka Echo mine site to conduct an aerial photography survey of the site. The aircraft pilot only became aware of the danger he was in after he had landed and was informed of the near-miss.

An Australian Transport Safety Board (ATSB) report says “this incident highlights the challenges associated with having a diverse mix of aircraft operating in the same airspace and the need for all pilots and operators to remain vigilant and employ see-and-avoid principles. The operator of the UAV reported that due to a small frontal area, a UAV may be difficult to see and therefore a potential for conflict exists, in particular with manned aircraft operating below 400 ft (122 m) AGL.

“Where other aircraft may be operating in the same airspace without radios, separation is limited to see-and-avoid principles. The limitations of unalerted see-and-avoid have been detailed in the ATSB’s research report Limitations of the See-and-Avoid Principle. The report highlights that unalerted see-and-avoid relies entirely on the pilot’s ability to sight other aircraft. Broadcasting on the correct frequency is known as radio-alerted see-and-avoid, and assists by supporting a pilot’s visual lookout for traffic.

“Prior to commencing UAV operations, direct communication with the pilots of other aircraft in the area may increase awareness and assist in preventing similar incidents from occurring. If the pilot of a manned aircraft communicates their intentions to operate in the same airspace as a UAV, the UAV operator may be able to land the UAV or take action to avoid potential conflict. The report is available at www.atsb.gov.au/publications/2009/see-and-avoid.aspx.