The European Aviation Safety Agency has published safety information bulletin SIB 2017-10 to remind pilots and air traffic controllers about the risks associated with wake turbulence encounters at high altitude and applicable precautionary measures. “With the increase in overall volume of air traffic and enhanced navigation precision, wake turbulence encounters in the en route phase of flight have progressively become more frequent in the last few years,” the bulletin said.
The document comes just six months after a Bombardier Challenger 604 at FL340 was severely damaged and its occupants injured when it encountered wake turbulence 12 nm from an Airbus 380 that had passed overhead in the opposite direction at FL350. As the bulletin noted, the so-called “heavy” and “super heavy” aircraft—such as the Airbus 340 and 380 and Boeing 747—are more prone to generate stronger vortices, although there is also potential from other large aircraft types.
Considering the high operating airspeeds in cruise and the standard 1,000-foot vertical separation in RVSM airspace, EASA said that wake can be encountered up to 25 nm behind the generating airplane, but “the most significant encounters are reported within a distance of 15 nm.” The bulletin concludes with illustrations that show various scenarios of wake turbulence encounters and recommended avoidance techniques.