⚖ Weather · FAA Aviation Weather Services / PHAK Chapter 13WX-016 · 119 of 261

What is the primary distinction between a SIGMET and an AIRMET?

ASIGMETs are issued only for convective weather; AIRMETs cover all other hazards.

BSIGMETs warn of severe meteorological conditions hazardous to ALL aircraft; AIRMETs warn of conditions primarily hazardous to light aircraft.✓

CSIGMETs are issued by flight service stations; AIRMETs are issued by the NWS.

Why →AIRMETs cover conditions primarily hazardous to light aircraft and limited-capability aircraft. SIGMETs cover severe or extreme conditions hazardous to ALL aircraft, including heavy jets. SIGMET conditions include severe/extreme turbulence, severe icing, dust/sandstorms reducing visibility below 3 miles, and volcanic ash.

The trap →Convective SIGMETs (WST) are a separate product for convective weather. Standard SIGMETs cover non-convective severe hazards. The AIRMET/SIGMET distinction is about severity, not the issuing authority (both come from the NWS Aviation Weather Center).

Field note →If a SIGMET is active for your area, conditions are severe enough to threaten large commercial jets. Any sUAS operation under an active SIGMET is extremely hazardous. SIGMETs are valid for 4 hours (6 hours for hurricanes).

SOURCE → FAA Aviation Weather Services / PHAK Chapter 13CHECKED JUL 16ACS III.A.K1MED

▶ Try it in a drill all weather questions →browse all 261 →report an issue

← WX-015 WX-017 →