Which inflight weather advisory should you refer to for icing and freezing levels?

The appropriate inflight weather advisory to refer to for icing and freezing levels is Airmet Zulu. This Airmet is specifically issued to alert pilots about moderate icing conditions and freezing levels which can impact aircraft performance and safety. Airmet Zulu provides crucial information, including the altitude where these conditions may occur, allowing pilots to make informed decisions to ensure safe flight operation.

In contrast, the other Airmets focus on different weather phenomena. Airmet Tango addresses turbulence and wind conditions, Airmet Sierra deals with IFR (Instrument Flight Rules) conditions and visibility issues, and Airmet Alpha is not a standard term in this context. Therefore, Airmet Zulu is the most relevant advisory for any concerns related to icing and freezing levels during flight.