Which is considered one of the most important sources of icing information?

A PIREP (Pilot Report) is considered one of the most important sources of icing information because it is first-hand information provided by pilots who are currently experiencing weather conditions during flight operations. PIREPs include critical details about atmospheric phenomena such as turbulence, cloud tops, and, importantly, icing conditions associated with specific altitudes and geographical locations.

This real-time data helps other pilots and air traffic controllers assess potential icing hazards, enabling them to make informed decisions about flight routes and altitudes. Since PIREPs reflect the actual experiences of pilots in flight, they are valuable for validating and enhancing meteorological forecasts and models, particularly concerning icing.

In contrast, while weather balloon reports, SIGMETs, and NOTAMs provide useful meteorological information, they do not offer the immediate and location-specific insight that PIREPs do regarding in-flight icing conditions. Weather balloons collect data at specific intervals and altitudes, SIGMETs focus on significant weather phenomena but may not detail icing specifically, and NOTAMs primarily inform about airport status and navigational changes rather than in-flight weather conditions.