Which aviation report provides critical information on turbulence and icing conditions?

The PIREP, or Pilot Weather Report, is the correct choice because it is a real-time report generated by pilots in flight, detailing the actual weather conditions they encounter. This includes valuable information about turbulence and icing, which are crucial for other pilots and air traffic controllers to be aware of for safety and operational purposes. PIREPs are essential for understanding current atmospheric conditions, especially because they come directly from those experiencing the turbulence or icing firsthand.

In contrast, ATIS (Automated Terminal Information Service) provides recorded information about weather conditions and airport information but does not include pilot-reported incidents of turbulence or icing. METAR (Meteorological Aerodrome Report) provides standardized weather observations but lacks the real-time feedback from pilots on in-flight conditions. TAC (Terminal Area Chart) is focused on navigation and visual aids and does not provide specific weather information. This makes the PIREP the most critical source for assessing turbulence and icing conditions in aviation.