What is a critical effect of ice, snow, or frost formation on an aircraft?

The formation of ice, snow, or frost on an aircraft significantly alters its aerodynamic properties, leading to a decrease in the angle of attack at which stalls occur. This is primarily due to the added weight and drag that ice or snow introduces, which changes the way airflow interacts with the aircraft's wings and control surfaces. Ice and frost disrupt the smooth flow of air, resulting in a lower critical angle of attack and contributing to an earlier onset of stall conditions.

As the surface of the wing becomes rough and irregular due to ice accumulation, the airflow experiences increased turbulence, reducing lift even at angles of attack that would normally be considered safe. Therefore, the aircraft can reach a stall at a lower angle of attack than in clean conditions. Understanding this effect is crucial for pilots and dispatchers when assessing aircraft readiness for flight in cold weather conditions, as it emphasizes the importance of proper de-icing and anti-icing procedures to maintain safe operational performance.