What is a SIGMET?

A SIGMET is defined as a significant warning about weather that could impact flight safety. This standard weather advisory is crucial for pilots as it provides information about hazardous weather conditions such as thunderstorms, severe turbulence, icing, and volcanic ash. It is specifically designed to alert pilots of potential dangers that could affect their flight operations, ensuring they are aware of adverse weather conditions that may require changes in flight plans or procedures.

The other choices do not accurately represent what a SIGMET is. For instance, a significant update on airport operations is generally related to notices that affect ground activities at airports and does not encompass weather advisories. Routine communications from air traffic control consist of standard operational updates and instructions that do not specifically focus on severe weather warnings. A standard operating procedure refers to established protocols pilots follow for flight operations, again not directly related to weather advisories like SIGMETs. Through this advisory, pilots receive essential updates that inform their decisions and contribute to overall flight safety.