What is the primary difference between ATIS and ASOS?

The primary difference between ATIS (Automatic Terminal Information Service) and ASOS (Automated Surface Observing System) lies in their functions and how they disseminate weather information. ATIS provides recorded weather information that is updated periodically, typically after a METAR report, which includes essential details like current weather conditions, runway information, and any significant notices for pilots. This means that pilots receive a summary of the weather that may not reflect real-time changes but rather information compiled from observed conditions.

In contrast, ASOS takes ongoing measurements of weather conditions in real-time, providing continuous data that reflects current atmospheric conditions including temperature, wind speed and direction, visibility, and precipitation. This system allows for the monitoring of real-time weather phenomena, making it a vital tool for immediate situational awareness at airports.

While there may be aspects of other options that are true or partially true, option B accurately captures the essence of the distinction: ATIS offers a periodic summary based on METAR data, while ASOS operates in real-time to monitor and report current weather conditions.