Final answer:
To avoid clear air turbulence, pilots use weather reports and forecasts, reports from other aircraft, and may reduce airspeed to recommended levels; there's no simple way to increase or decrease altitude that guarantees avoidance of CAT.
Step-by-step explanation:
To avoid clear air turbulence (CAT), the common practice is not to attempt to fly through it quickly or necessarily to change altitude haphazardly, as rapid altitude or speed changes can potentially exacerbate the situation. Commercial pilots typically use weather reports and forecasts to avoid areas where CAT is likely, and they may also get reports of CAT from other aircraft. It's worth noting that CAT is difficult to detect with onboard radar because it occurs in clear air without the presence of moisture needed for radar reflection. As a result, the best course of action is to rely on reports and forecasts, and then alter the flight path to avoid the turbulent areas as much as possible. If encountered, pilots tend to reduce airspeed to the recommended turbulence penetration speed to minimize stress on the aircraft. Ultrasonic sensors, LIDAR, and onboard systems designed to detect CAT before encountering it are in various stages of research and implementation.