Which symbol represents Radioactive Materials on a SIGWX chart?

• A. Severe Aircraft Icing
• B. Radioactive Materials
• C. Tropopause LOW
• D. Surface Cold Front

Answer: (B)

On a SIGWX chart, aviation hazards are shown with specific symbols in the legend, including one category for radiological hazards. The symbol for Radioactive Materials is designed to alert crews to potential radiological release risks in the airspace. This is the best answer because it directly communicates a non-meteorological hazard—radiation risk—that the chart explicitly marks with its own symbol. The other items correspond to meteorological features with their own distinct icons—severe aircraft icing indicates icing conditions, a tropopause low is an upper-level atmospheric feature, and a surface cold front marks a boundary between air masses—so they do not signify radiological danger.