A dispatcher receives a report of severe turbulence affecting a wide area along a planned route, unrelated to any thunderstorm activity, expected to impact all categories of aircraft. Which hazardous weather product is appropriate for this condition, and why is an AIRMET insufficient?
- AA Convective SIGMET, because turbulence anywhere requires a convective advisory
- BA SIGMET, because severe turbulence is significant enough to be hazardous to all aircraft, not just small/light aircraft as with an AIRMET
- CAn AIRMET Tango, because turbulence advisories are always issued as AIRMETs regardless of intensity
- DA Center Weather Advisory, because it supersedes both SIGMETs and AIRMETs for turbulence
Show answer & explanationAnswer & explanation
Correct answer: B. A SIGMET, because severe turbulence is significant enough to be hazardous to all aircraft, not just small/light aircraft as with an AIRMET
SIGMETs are issued for weather considered significant to the safety of all aircraft, including severe turbulence, severe icing, dust/sandstorms reducing visibility below 3 statute miles, and volcanic ash. AIRMETs (such as AIRMET Tango) cover moderate turbulence primarily hazardous to smaller aircraft; because the report describes severe (not moderate) turbulence, a SIGMET is the correct product.
Why the other options are wrong
- A. Convective SIGMETs specifically address thunderstorm-related hazards; this turbulence is unrelated to convection.
- C. AIRMET Tango covers moderate turbulence and sustained surface winds ≥30kt, not severe turbulence, which requires escalation to a SIGMET.
- D. A CWA is a supplemental, short-fuse product used between SIGMET/AIRMET issuances, not a replacement or superseding product.
SIGMET Issuance Criteria
A SIGMET is issued for weather phenomena significant to the safety of all aircraft, including severe icing, severe turbulence, dust/sandstorms with visibility below 3SM, and volcanic ash, distinct from AIRMETs which address hazards primarily affecting smaller aircraft.
- Valid for up to 4 hours (6 hours for hurricane-related SIGMETs)
- Covers severe or greater turbulence and icing, unlike AIRMET's moderate threshold
- Unscheduled and issued as needed when criteria are met
Memory trick: SIGMET = 'Significant for everyone', AIRMET = 'Advisory mostly for the little guys'.