A PIREP is a report of meteorological phenomena that is ___.

• A. reportable on the weather observation
• B. encountered by aircraft in flight
• C. of importance to the controller
• D. of importance to the pilot

Answer: (B)

The key idea is that a PIREP is an in-flight report made by the pilot about weather phenomena actually observed during the flight. Pilots share conditions encountered—such as turbulence, icing, cloud layers, reduced visibility, wind shear, or other significant weather events—to help other pilots and controllers anticipate hazards and adjust routing or flight planning. This in-flight, firsthand information distinguishes PIREPs from ground-based observations like METARs, which describe conditions at a fixed location and time on the surface. While reports are useful to both pilots and controllers, the defining feature is that the weather phenomena are observed and reported from within the aircraft during flight.