Commercial Aviation Encounters with Severe Low Altitude Turbulence

Turbulence encounters continue to be one of the largest sources of personal injury and fatalities in both commercial and general aviation. A significant percentage of these encounters occur at low altitudes, without warning, and away from the high reflectivity storm areas where pilots typically anticipate severe wind shear and/or turbulence.

This paper presents analysis of some recent commercial aviation encounters with severe low altitude turbulence. While the aircraft altitude, attitude, and airspeed fluctuations were comparable to those experienced in the well-known hazardous microburst wind shear cases, no warnings were generated by the ground-based wind shear detection systems. Our investigation of the meteorological conditions surrounding these incidents reveals that they were caused by buoyancy waves, a phenomenon that current wind shear detection systems are not designed to detect.

We describe the various environmental characteristics and radar signatures of buoyancy waves and discuss techniques that might be used to detect them. The results presented in this paper show that, under certain circumstances, buoyancy waves can cause severe low altitude turbulence that is a serious hazard to commercial air traffic.