by Nick Kremer
Navigation Systems Radio Engineer, MnDOT Aeronautics
Published in Midwest Flyer Magazine April/May 2024 Digital Issue
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 and kept working? More importantly, how can you trust it to make safety-critical go/no-go decisions?
You can get current weather information from any of MnDOT’s 79 AWOS stations at airports throughout the state. Visit mndot.gov/aero/navigationsystems/awos-map-online.html.
In Minnesota, MnDOT Aeronautics maintains 79 AWOS stations 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 monitors the network for failures, faulty sensors, and the occasional offline situations. Additionally, FAA circular AC 150/5220 Automatic Weather Observing Systems (AWOS) for Non-Federal Applications requires the stations to be inspected quarterly or tri-annually, depending on the station model. During these required checks, preventative maintenance is carried out. Several parameters are verified through these frequent checks; a barometer, visibility, and ceilometer (sky condition) are a few of the assessments completed.
A technician works on AWOS equipment.
Once a year, the entire AWOS goes through an annual revalidation inspection. An FAA inspector witnesses the annual revalidation inspection and includes the checks mentioned above but with more detail. In addition, temperature/dewpoint, wind sensors, and radio transmitters are also checked.
A final set of eyes on each of the state’s AWOS stations is the National Oceanic and Atmospheric Administration (NOAA). NOAA uses data from Minnesota’s AWOS stations and will notify MnDOT Aeronautics staff of any anomalies they note. Should a repair be needed, a NOTAM will be issued to help provide pilots advance notice of the missing parameter.
All repairs and inspections to Minnesota,s AWOS stations 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. While that effort is underway, it will take years to complete. It’s also important to note that Minnesota has additional weather systems that federal agencies maintain.
If you experience issues with an AWOS station and a NOTAM is not in place, please notify the MnDOT Aeronautics Navaids team via email at navaids.dot@state.mn.us. If you have questions about Minnesota’s AWOS stations or system, contact Nick.Kremer@state.mn.us.
See Minnesota AWOS locations, and get local weather online.
