Recent increases in reported losses of required minimum in-flight separation of aircraft, known as airproxes in a number of European countries, and of altitude deviations from air traffic control (ATC) clearances by flight crews, called level busts, generated enough concern that in June, the stakeholders convened a two-day Airborne Conflict Safety Forum in Brussels, Belgium. The numbers for both airproxes and level busts are small relative to traffic volume, but they are viewed as critical safety indicators because of the severity of potential consequences, presenters said.
“In European airspace with prescribed separation minima, there are approximately 150 losses of separation per million flights,” says the final report by forum organizers. “Since each flight receives on average 15 executive instructions in the en route environment, this is equivalent to one loss of separation per 100,000 instructions. … IATA [International Air Transport Association] safety …
