What is a SIGMET and when is it issued?

• A. A weather advisory for minor turbulence only near ground level.
• B. A weather advisory for significant weather affecting flight safety, issued for aviation routes.
• C. A weather advisory only for mountain wave conditions.
• D. A forecast of expected temperatures.

Answer: (B)

A SIGMET is a weather advisory for significant weather affecting flight safety, issued for aviation routes. It alerts pilots and air traffic controllers to weather phenomena that could threaten aircraft in flight along en-route portions of the routes, such as severe icing, severe turbulence, volcanic ash clouds, sand or dust storms, or tropical cyclones. It’s not limited to ground-level conditions and is distinct from forecasts of temperature. Thunderstorms and convective activity are addressed separately under Convective SIGMETs, while a SIGMET covers other significant weather that can impact flight safety.