Since the early days of aviation, the taking and dissemination of surface aviation observations has been an essential function for safe and efficient flight. The cost of personnel and material limits the availability of stations and it has been increasingly practical to automate many observing functions. The need for additional weather sources spurred production of several automated systems, one of which is the AWOS.
AWOS (Automated surface Weather Observing System) is a highly sophisticated data sensing, processing and dissemination system.
The differences between reports from a certified observer and the AWOS are negligible for "Objective" elements. In other words, the observer and the AWOS unit will produce the same results for wind, temperature, dew point, precipitation accumulation and pressure.
For "Subjective" elements such as visibility and sky condition, the AWOS uses a fixed location and time averaging technique while certified observers use a fixed time and spatial averaging technique. Although the techniques are different, the manual and automated techniques yield remarkably similar results within the limits of their respective capabilities. This would include:
Because of the averages used by the AWOS, it takes a little longer for the reported ceiling or visibility to "go up" or "go down" than would a manual observation.
Updated weather reports are produced once each minute, however, observations are only transmitted every 20 minutes to the Flight Service and NWS. Other ways of receiving the information are over a radio frequency or by phone.
Page Last Modified: 01/04/08 10:54 EST
This page can be viewed online at: http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/alaskan/flying_ak/awos/