At what turbulence intensity level must controllers solicit PIREPs?

The correct choice is moderate turbulence intensity. Controllers are encouraged to solicit Pilot Reports (PIREPs) when encountering moderate turbulence because it represents a level of turbulence that can significantly affect aircraft handling and crew workload. Moderate turbulence may cause changes in altitude and attitude, creating a need for pilots to actively manage their aircraft. By gathering PIREPs at this level, air traffic controllers can enhance situational awareness for all aircraft in the area, helping to ensure safety and facilitate smoother operations.

While light turbulence typically does not pose a significant risk to flight operations, and severe or extreme turbulence usually demands urgent reporting for operational awareness, the moderate level serves as a threshold where feedback from pilots is crucial for developing a comprehensive understanding of the turbulence conditions being experienced in real-time. This collected data is invaluable for improving safety protocols and determining alternate routing around areas of turbulence.