Edmonton, Alberta, 20 October 2016 — The limitations of the “see-and-avoid” principle in preventing collisions were illustrated once again in the Transportation Safety Board of Canada (TSB) investigation report (A15W0087) into a June 2015 mid-air collision between two small aircraft near Fort McMurray, Alberta.
On 21 June 2015, a Cessna 172 was conducting a training flight in the practice area northeast of the Fort McMurray airport with a student pilot and flight instructor on board. At the same time, a privately operated Cessna 185 on amphibious floats was descending through the practice area on its way to the Fort McMurray airport. Both pilots were conducting visual flight rules (VFR) flights and relying primarily on the see-and-avoid principle to avoid collisions with other aircraft operating under VFR. This principle is based on active scanning, and the ability to detect conflicting aircraft and to take appropriate measures to avoid such aircraft. The two aircraft collided at 2800 feet, leading to the left float separating from the Cessna 185, and the in-flight breakup of the Cessna 172. The occupants of the Cessna 172 were fatally injured. The Cessna 185 pilot was uninjured, though the aircraft sustained substantial damage.
The investigation found that neither pilot saw the other aircraft in time to avoid a mid-air collision, because of the inherent limitations of the see-and-avoid principle as the primary means of preventing collisions between aircraft flying in uncontrolled airspace. This is due to factors such as the limitations of human vision, restricted visibility from the aircraft cockpit, pilot workload, and difficulties in spotting small aircraft at a distance. These limitations have been of concern in previous investigations to the TSB and other investigative bodies.
There are other measures pilots flying in uncontrolled airspace can take to mitigate the risks of collision. These include flying along published VFR routes, actively providing and listening for traffic advisories on the radio, and using aircraft collision avoidance systems to detect aircraft flying nearby. If these measures are not taken, there is an increased risk of collision between aircraft.
Following the occurrence, NAV CANADA published additional information about the flight training practice area northeast of the Fort McMurray Airport in its aviation publications.
See the investigation page for more information.
The TSB is an independent agency that investigates marine, pipeline, railway and aviation transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
Transportation Safety Board of Canada (TSB)
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