When a wind shift occurs, what type of observation is required?

When a significant wind shift occurs, a SPECI report is required. SPECI reports are special weather conditions reports that provide updates to the standard METAR observations. They are issued when there are significant changes in weather conditions, which includes shifts in wind direction or speed that may affect aviation operations. This allows pilots and air traffic controllers to be informed of the latest weather conditions, particularly those that may impact takeoff, landing, or in-flight navigation.

In contrast, a METAR is a routine weather report generated at regular intervals and would not specifically address immediate weather changes like a wind shift. AWOS (Automated Weather Observing System) provides continuous weather updates but is not a reporting standard like SPECI or METAR. TAF (Terminal Aerodrome Forecast) provides weather forecasts, not current observations, and thus is not relevant to the immediate reporting of a wind shift.