By Nick Kremer, MnDOT Aeronautics
As a pilot or member of a flight crew, you listen in to a weather briefing at the start of every flight and before landing, but have you ever thought about how that computerized voice brings you the weather and is maintained? More important, how can you trust it to make safety-critical go/no-go decisions?
In Minnesota, MnDOT Aeronautics maintains 79 automatic weather observing stations (AWOS) at local public airports throughout the state. Most state-owned AWOS stations were installed during the 1990s or early 2000s, making them quite old compared to most electronic devices. Fortunately, we have tools to monitor the system's health—plus reports from the pilots and airport managers who rely on the systems.
Every AWOS maintained by MnDOT Aeronautics is connected through a display computer in the terminal building. MnDOT Aeronautics staff monitor the network for failures, faulty sensors, and the occasional offline situation. Additionally, FAA Advisory Circular 150/5220-16E (Automated Weather Observing Systems for Non-Federal Applications) requires that stations be inspected quarterly or tri-annually, depending on the station model. Preventive maintenance is conducted and several parameters are verified, while barometer, visibility, and ceilometer (sky condition) are a few of the assessments completed.
Once a year, the entire AWOS is put through an annual revalidation inspection—witnessed by an FAA inspector—that includes the checks mentioned previously but in more detail. Temperature/dewpoint, wind sensors, and radio transmitters are also checked.
The National Oceanic and Atmospheric Administration (NOAA) provides a final set of eyes on each of the state’s AWOS stations. NOAA uses data from the stations and will notify MnDOT Aeronautics staff of any anomalies they notice. Should a repair be needed, a NOTAM will be issued informing pilots of the missing parameter.
All repairs and inspections to Minnesota’s AWOS system are carried out through teamwork between MnDOT Aeronautics employees and a contracting firm specializing in aviation navigational aids. Eventually, every AWOS station in Minnesota will need to be replaced with newer, more modern equipment. Although that effort is underway, it will take years to complete. Minnesota also has additional weather systems that federal agencies maintain.
If you experience issues with an AWOS and a NOTAM is not in place, please notify the MnDOT Aeronautics navaids team via email at [email protected]. If you have questions about Minnesota’s AWOS stations or system, contact [email protected].
Current weather information from MnDOTs AWOS stations at airports throughout the state is available online with MnDOT's new navaids weather app.
—Nick Kremer is a navigation systems radio engineer with MnDOT Aeronautics.
