# Real-Time Image Analysis for Intelligent Aircraft De-Icing Decision Support Systems
## 2 Literature Review  
Aircraft icing constitutes one of the most serious threats to flight safety, affecting aerodynamics, aircraft mass, and the functioning of key onboard systems. Intelligent decision support systems based on real-time image analysis can significantly improve the effectiveness of de-icing procedures, minimizing the associated operational risk. The literature provides extensive information on aircraft icing, its causes, and its consequences for the safety of flight operations. Intensive research on this phenomenon began in the 1980s, when NASA, in response to the crash of an Air Florida Boeing 737 in 1982, initiated a comprehensive research program using a De Havilland DH-6 Twin Otter aircraft as a test platform. Initially, the research focused on measuring the properties of icing clouds, and then expanded the analysis to include the impact of icing on aircraft performance, using, among other things, stereophotography to document ice shapes on wings and the analysis of aerodynamic losses. The Flight Safety Foundation and the University of British Columbia published detailed studies on the mechanisms of icing formation and its impact on flight safety, highlighting the key role of supercooled water droplets occurring at temperatures from 0 \({}^{\circ}\)C to \(-\)40 \({}^{\circ}\)C. Contemporary research, conducted by institutions such as the AOPA Air Safety Institute and the FAA, provides valuable information on the effectiveness of anti-icing systems and operational strategies minimizing the risks associated with this phenomenon [13; 14]. Aircraft icing leads to serious aerodynamic consequences that directly affect flight safety. The primary mechanism is the disruption of airflow around the airframe, which results in increased aerodynamic drag and a simultaneous decrease in lift. Even a thin layer of ice, about 60 mm (1/4 inch) thick, can significantly impact the aerodynamic characteristics of the aircraft, increasing drag by as much as 40 to 80% and requiring a higher angle of attack and greater speed to maintain flight. As a result, an aircraft with iced surfaces stalls at higher speeds and behaves unpredictably. Icing also increases the aircraft's mass and can shift its center of gravity, further complicating control of the aircraft. Particularly dangerous is tailplane icing, which can lead to so-called tail stall and sudden nose-down pitching of the aircraft. In the case of engines, icing of air intakes or carburetors leads to power loss or complete failure, which poses a direct threat to the continuation of the flight. Aircraft icing is classified according to various criteria, taking into account both the location and the characteristics of the ice formed. The basic division includes structural icing (affecting the external surfaces of the aircraft) and induction icing (related to engine systems) [15; 16; 17]. Within structural icing, several characteristic types of ice can be distinguished. Clear ice forms at temperatures from 0 \({}^{\circ}\)C to \(-5\)\({}^{\circ}\)C and is characterized by a smooth, transparent structure that significantly increases aerodynamic drag and is difficult to remove. Rime ice, which forms at temperatures below \(-10\)\({}^{\circ}\)C, has a porous, milky-white structure that disrupts airflow, although it is easier to remove. Mixed ice is a combination of both types and occurs at temperatures from \(-5\)\({}^{\circ}\)C to \(-10\)\({}^{\circ}\)C, creating irregular, uneven deposits that are particularly dangerous for the aircraft's aerodynamics. Hoar frost forms as a result of the direct deposition of water vapor on cold surfaces and, although it does not radically change the shape of the wings, it reduces lift by up to 30% and increases drag by 40%. Wet snow poses an additional threat, as it contains water particles that can freeze on aircraft surfaces, while dry snow usually does not cause icing [14; 18; 19]. Effective prevention of icing requires an integrated approach that combines appropriate technical systems with operational procedures.