What is a SIGMET?

• A. A report on routine weather observations
• B. A significant meteorological event affecting the safety of aircraft operations
• C. A notification of airspace changes
• D. A type of flight plan submission

Answer: (B)

A SIGMET, or Significant Meteorological Information, specifically refers to a weather advisory issued for conditions that significantly impact the safety of aircraft operations. This includes hazardous weather phenomena such as severe turbulence, thunderstorms, icing, volcanic ash, and dust storms that pose a threat to the safety of flights.

These advisories are critical because they provide pilots with essential information about potentially dangerous weather conditions that they may encounter en route. Unlike routine weather reports, which can provide general atmospheric conditions, SIGMETs focus on significant weather events that require immediate attention and may affect flight safety.

In contrast, the other options do not adequately capture the purpose or significance of a SIGMET. Routine weather observations are indeed valuable for understanding daily weather patterns, but they lack the urgency that defines a SIGMET. Notifications about airspace changes refer to regulatory or structural adjustments and are not specifically about weather phenomena. Similarly, a flight plan submission is a procedural step in flight operations unrelated to directly communicating significant weather hazards. Therefore, the emphasis on safety and the nature of the information provided makes option B the correct answer.