by Cassandra Isackson
Director, Minnesota Office of Aeronautics
As we approach the periods of winter where wind-blown snow modifies the landscape almost daily, we must also think about the other important winter weather factors that can impact airports and aviators.
The team of professional pilots in your Office of Aeronautics are well aware of the potential hazards that can exist in the season. They gladly share their experience and knowledge to help keep all Minnesota aviators and airports operating safely.
They advise that “hoar frost” can develop in clear air on an aircraft or automobile for instance when the nighttime temperature is at or below freezing and the metal surface of the vehicle or aircraft comes in contact with the moist air of the night. This is the frost one might see growing in fine needle-like structures on fences and weeds. While hoar frost may not be as immediately dangerous as clear ice as it impacts an aircraft’s wings shape and lift capabilities, it cannot be left on wings and control surfaces, as it is especially dangerous on takeoff.
Our professional pilots also mentioned “black ice.” Black ice is a thin sheet of ice that can form on a sidewalk, road, ramp, taxiway or runway when there is sufficient moisture and the temperature is at, or below freezing. In fact, black ice is not black at all and is actually transparent, often appearing as a shiny, black spot or area on the road, taxiway or runway. As temperatures fall to or below freezing (32 degrees Fahrenheit), it may form very quickly on bridge decks, or on patches of road. It can also form rapidly on runways or taxiways that may pass over a culvert.
We remind you to use caution and stay alert to conditions when flying, driving, or even just walking. If you discover a patch of black ice at your airfield that isn’t sanded, let your airport manager know about it. They work hard to keep your airfield safe at all times, but it is possible that rapidly fluctuating weather conditions can cause equally rapidly formed slick spots to develop.
If you have questions, contact your favorite flight instructor or attend a flight safety seminar to learn the latest procedures, techniques and information to handle conditions you may encounter at the airport, as well as during flight. Please continue to make safety priority-one so that you and yours can enjoy the beauty of the season.