Which AIRMET code is used for widespread IFR conditions?

The AIRMET code that indicates widespread IFR (Instrument Flight Rules) conditions is Sierra. This code is specifically used to inform pilots about areas where visibility is reduced to less than 3 statute miles or where ceilings are lower than 1,000 feet above the ground. Sierra alerts pilots to these potentially hazardous conditions, which can significantly impact flight safety, especially for those flying under VFR (Visual Flight Rules) where high visibility and cloud clearance are required.

The other codes serve different purposes: Tango refers to moderate turbulence and wind shear, Zulu indicates freezing levels and potential icing conditions, and Bravo is not an AIRMET designation at all. Understanding these specific codes is crucial for pilots to make informed decisions about their flights in varying weather conditions.