Definition
A network of automated weather stations located at airports that continuously measure and report surface weather conditions, including wind speed and direction, visibility, cloud height, temperature, dew point, altimeter setting, and precipitation. Reports are updated minute-by-minute and transmitted by radio, telephone, and digital data link for use by pilots, controllers, and forecasters.
Plain English
An automatic weather station at an airport that takes continuous readings of the local weather and broadcasts them so pilots and controllers always have current conditions.
Context Anchor
Pilots encounter Automated Surface Observing Systems during preflight planning and while checking current airport weather by radio, phone, or aviation weather services.
Derivation
Automated means it runs without a human observer. Surface refers to weather measured at ground level, not aloft. Observing simply means watching and recording. Together: a system that watches and reports weather at the airport surface, on its own.
Why Pilots Care
Provides reliable, up-to-the-minute weather at remote or unstaffed fields so pilots can make safe go/no-go and approach decisions.
Grounding Statement
Picture a set of weather sensors at the airport continuously checking the wind, clouds, and pressure so a pilot can get a current report before arriving or departing.
Intuition Check
Automated does not mean perfect or complete. It means the report is produced by equipment, so pilots should still compare it with what they see outside and with other weather information when needed.
Example Sentence 1
Twenty miles out, the pilot tuned the ASOS frequency and heard winds 240 at 8, visibility 10, ceiling broken at 4,500.
Example Sentence 2
Automated Surface Observing Systems reports helped the student manage workload by giving instant destination weather during cross-country planning.