Which system uses sensors, computers and communication systems to automatically record and disseminate atmospheric conditions continuously at one-minute intervals?

• A. The Aeronautical Information Manual (AIM)
• B. The Pilots Handbook of Aeronautical Knowledge
• C. Operational Necessity and Safety of flight
• D. Automated Surface Observing System (ASOS)

Answer: (D)

Automated Surface Observing System provides continuous, minute-by-minute weather data at airports by bringing together sensors, computing, and communications to record and broadcast atmospheric conditions. It uses instruments like wind sensors, temperature and dew point sensors, barometers, visibility and ceiling sensors, and precipitation detectors to gather real-time data, which is then processed and transmitted in aviation weather products such as METARs. This setup lets pilots and air traffic controllers access current conditions within a minute of observation. The other options are not automated measurement systems: one is a government publication of procedures, another is a pilot training book, and the last is a general phrase about flight safety, not a weather observation system.