What is the critical vertical wind shear value for probable moderate or greater turbulence?

The critical vertical wind shear value associated with probable moderate or greater turbulence is recognized as 6 knots per 1,000 feet. This threshold is significant for pilots and aviation professionals because wind shear can lead to sudden and dangerous changes in aircraft performance, particularly during takeoff and landing phases when the aircraft is closer to the ground.

When vertical wind shear exceeds 6 knots per 1,000 feet, it indicates a substantial change in wind speed or direction with altitude. Such changes can disrupt the smooth flow of air over the wings, impacting lift and potentially causing the aircraft to experience turbulence. Understanding this critical value helps pilots prepare for and mitigate the effects of turbulent conditions during flight.

The other values provided in the options represent either lower or higher thresholds. The lower values could indicate less severe conditions, while higher values typically signal much more severe turbulence, which may not commonly occur in typical flight conditions or may lead to extreme turbulence situations that require different operational considerations.