One of the meteorological phenomena that can affect an aircraft is the icingIce deposits on an aircraft and occurs when supercooled liquid water freezes upon impact. This phenomenon can be a critical aspect of aviation safety, making it essential to understand its importance in the context of meteorology applied to aviation.
In this article we are going to tell you all the characteristics, origin and importance of icing.
What is icing
We are talking about a meteorological effect that takes place in the upper part of the atmosphere and that can affect the aircraft when it passes through these areas. In this phenomenon, the ice mainly adheres to the elements that are exposed to the wind. All the elements that protrude from the plane can be altered due to icing.
Let's see what are the main alterations that can cause icing in the parts that protrude from the aircraft cell:
- Reduced visibility. If ice adheres to certain parts of the aircraft, it can cause reduced visibility at short and medium distances.
- Alterations of aerodynamic properties: When the means of transport is air, the aerodynamic properties are essential for efficient use of fuel. Ice can create instability in the aircraft's aerodynamics.
- Weight gain: The aircraft may experience an increase in weight depending on the ice that remains due to the surface.
- Power loss: it is a direct consequence of weight gain. As the weight increases, the aircraft loses power little by little.
- Vibrations: These delays on a continuous basis can cause structural fatigue in all the elements of the aircraft.
We know that icing on an aircraft can occur within clouds, mist, or fog. It all depends on the environmental conditions at the time. It can also occur within precipitation. In this case, it is called freezing rain. This phenomenon highlights the importance of understanding the different types of clouds and their effects on aircraft, which can be explored further in articles on cloud characteristics such as the following: stratus.
Protection against icing
The first thing to know to protect yourself from icing is to know those areas where it tends to occur more frequently. It is not advisable to fly in areas where meteorological conditions are favorable for icing formationOne way to protect against this phenomenon is to have de-icing equipment to help remove all the buildup. However, this protective measure is more expensive because it must be installed on the aircraft.
There are anti-icing systems that prevent ice from forming and adhere to the surface. These systems come in several types:
- Coated Mechanics: These are those that have a matic coating that, when inflated with air in the engine, breaks the ice. They are usually used on the wings and tail fins.
- Thermal: They are those electric heaters that can be used in the Pitot tube. They are also air heaters that can be used on the leading edge of the water, on the propellers, on the carburetor and on the tail tail.
- Chemicals: These are various baths made with substances that help keep the supercooled water in a liquid state. It's most commonly used on propellers and windshields.
Triggers
Let's analyze the factors that trigger icing. First of all, it requires a liquid water content at a very low ambient temperature (most commonly below zero) and an aircraft surface temperature also below zero. Large droplets may occur. so inside the clouds with temperatures of -2 and -15 degrees and small drops that are found at temperatures of -15 and -40 degrees.
Some of the favorable environmental conditions for the generation of icing are convergence at low levels and atmospheric instability. During atmospheric instability, strong rises of masses of hot water are very frequent, which, when they collide with a mass of cold water, generate vertically developing clouds. The pockets of cold air in height favor vertical movements and the development of clouds and greater instability.
The passage of frontal systems with high-speed winds also often causes icing. Depending on the area the aircraft passes over, this effect is more or less likely to occur. For example, mountainous terrain often favors rising air and contributes to an increase in the number of water droplets that form clouds. This increases the likelihood of icing. The effect of the coasts is quite similar to the orographic effect. Humid air originating from the sea reaches a level of decondensation as it rises. As altitude increases, a higher liquid water content is generated in the clouds, increasing the likelihood of icing.
Basic shapes
Let's analyze the basic forms of icing that exist:
- Granulated ice: It is a white, opaque, porous ice that comes off quite easily. They are usually formed at temperatures between -15 and -40 degrees mainly from small droplets. The process of forming this type of granulated ice is done quite quickly.
- Clear ice: This is a clear, transparent, smooth type of ice that is more difficult to break off. It usually forms at temperatures between -2 and -15 degrees Celsius and is mostly made up of large drops. The freezing process of this type of ice is quite slow. The drops can flow slightly before thawing. This increases the freezing surface area. The flow of air around the aircraft wing can be disrupted to a greater extent than with the previous type of ice.
- Freezing rain: It's one of the most dangerous types of icing that exists. It's a very dangerous form of icing on aircraft. The ice is transparent, and the precipitation remains intact and uniform over the plane. A thermal profile at altitude that has an inversion at mid-levels is quite favorable for the formation of freezing rain.
I hope that with this information you can learn more about icing and its characteristics.