What is the definition of a SIGMET?

A SIGMET, which stands for Significant Meteorological Information, is defined as a significant weather advisory that is crucial for in-flight operations. It provides pilots with information about hazardous weather conditions that may impact flight safety, including phenomena such as severe thunderstorms, turbulence, icing, or volcanic eruptions. SIGMETs are issued by meteorological authorities and are essential for pilots to make informed decisions while navigating through or around areas affected by these weather conditions.

In contrast, other options do not accurately reflect what a SIGMET entails. For example, airspace restrictions involve specific regulations and limitations imposed for safety or security reasons, which differ from the weather-focused information provided by SIGMETs. A pilot's weather briefing prior to departure typically includes a broader range of information, including forecasts and not just significant weather advisories. Lastly, standard operational procedures during turbulence encompass protocols a pilot follows during flight but do not specifically relate to the issuance of SIGMETs. Therefore, focusing on hazardous weather, option B is the only correct representation of a SIGMET's purpose within aviation safety.