Which description is true about SIGMETs?

• A. They warn of minor weather hazards.
• B. They are issued for significant weather phenomena affecting several aircraft.
• C. They only apply to tropical zones.
• D. They are forecasts for the next 24 hours.

Answer: (B)

SIGMETs warn pilots and air traffic controllers about significant weather phenomena that can affect the safety of flight for multiple aircraft over a region. They’re issued when such hazards are occurring or expected to develop and persist, not for minor conditions and not only for tropical areas. They aren’t forecasts for the next 24 hours; instead, they have a limited validity period (typically up to 4 hours, or up to 6 hours for volcanic ash). This makes the description that they are issued for significant weather phenomena affecting several aircraft the best fit.