Flying Safely in the Snow

aircraft on a snowy runway

Alliance Aviation Group always puts safety above all when flying the skies, but have you ever wondered how an aircraft can take off and operate safely in the snow? There are essential safety considerations to take into account to ensure functionality of an aircraft when it is cold or snowing.

Snow, slush and ice are safety hazards that can reduce lift as much as 30%. These factors therefore raise drag by 40% consequently increasing the distance an aircraft needs to take off. As a result, de-icing and anti-icing are necessary solutions to prevent these negative effects.

De-Icing to Safely Fly in the Snow

The first step in removing ice, snow and slush is to heat a propylene glycol solution to approximately 150 degrees Fahrenheit and to pressure spray the aircraft to blast off “contaminants.” This solution -called Type I- is combined with water, the ratio depending on the weather conditions and automatically adjusted in response to weather sensors. Type 1 fluid is very slippery and typically sprayed at a 45-degree angle to avoid direct surface contact as well as windows.

This may sound like a labor-intensive process, however in more frigid conditions, de-icing alone is not enough and anti-icing must be applied as a result.

Anti-Icing

Secondly, the anti-Icing process involves a thicker, unheated fluid called Type IV, which smells similar to maple syrup. Applying Type IV prevents ice and debris from adhering to a de-iced surface of the aircraft for a longer period of time than Type I due to the absence of water in the fluid.

“Think of it like a baby diaper,” said Gene Herrick, head of American Airlines’ de-icing operations at ORD. “The anti-ice chemicals absorb water and prevent the water from sticking to the wing.”

Due to this process the external airflow is turned off so as not to circulate chemicals through the air in the cabin. You may think after all this work that the anti-icing fluid will remain on the plane until touchdown at your destination, however through the takeoff process most of the fluid is already gone and by 1.000 ft above the ground there is none left. 

How Much Time Do Pilots Have?

“Holdover time” describes the amount of time between spraying the fluid and takeoff that the de-icing will remain effective. De-icing fluid lasts up to 22-minutes as its main purpose is to remove debris from the onset, while in contrast anti-icing functions for longer periods of time up to 160 minutes depending on weather conditions. Holdover times are also determined through visibility of snow build up. Heating pads that melt falling snow also measure precipitation and even use mobile apps.

Pilots Flying Safely in the Snow

The Pilot in Command — the captain of the aircraft — has the final say as to whether to depart after de-icing and/or anti-icing as well as what the holdover time will be. If the plane has not yet departed and holdover time is exceeded the captain has a choice to repeat the de-icing process or to visually inspect the aircraft. The visual inspection requires the first officer to walk the cabin, which can create some anxiety among passengers so it is essential to make a calm announcement before the commencement of the inspection to maintain peace of mind.

While de-icing and anti-icing may seem like an inconvenient delay it is an essential safety component that allows us to safely fly through the soar through the skies in frigid weather. Book with us today and fly home for the holidays with Alliance Aviation.

Aircraft flying safely in the snow

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