FAA Jeppesen Instrument Rating Test 2025 – 400 Free Practice Questions to Pass the Exam

The correct answer indicates that ice, snow, or frost with a roughness similar to mid-course sandpaper results in a 30% reduction in lift. This understanding is crucial for pilots, as even minor amounts of contamination on the wings can significantly degrade the aircraft's aerodynamic performance.

When considering the impact of surface roughness on lift, it's important to recognize that aircraft wings rely on smooth surfaces to maintain the flow of air over them. Rough or contaminated surfaces disrupt the airflow, leading to increased drag and reduced lift. In the case of snow or frost, which can create a texture akin to mid-course sandpaper, the turbulent air caused by this roughness increases the likelihood of flow separation off the wing surfaces. This separation decreases lift efficiency, thus requiring more attention from pilots regarding pre-flight checks and de-icing procedures.

Understanding that a rough surface can lead to a 30% reduction in lift forms a critical part of flight safety, emphasizing that even seemingly negligible accumulations of ice or frost demand effective removal before flight operations. This highlights the importance of proper de-icing procedures and diligence in assessing wing conditions prior to takeoff to ensure adequate lift is generated for safe flight.