Risk-Adaptable Access Control (RAdAC) This paper considers the impediments of traditional access control approaches to sharing of. information. It describes a concept for an access control model that emulates real world decision-. making, considering operational need and security risk as part of each access control decision, and.
Turbulence can occur in the lowest part of the troposphere during the daytime when heating of the sun causes convective mixing of the air. Once the airplane rises above this turbulent boundary layer, the air becomes smoother. But other processes can also cause these up- and down-drafts.
Wake turbulence can occasionally, under the right conditions, be heard by ground observers. On a still day, heavy jets flying low and slow on landing approach may produce wake turbulence that is heard as a dull roar/whistle. Often, it is first noticed some seconds after the direct noise of the passing aircraft has diminished.