2025 De-Icing Complete Practice Test Guide

The maximum allowable thickness of frost on the underside of the wings near the fuel tank is critical for maintaining aircraft performance and safety. Frost can significantly affect the aerodynamic properties of the wings, leading to reduced lift and potential handling issues during takeoff and flight.

In this context, a thickness of 1/8 inch is deemed acceptable because it represents a limit beyond which the risk of compromised aerodynamics increases considerably. Keeping frost to this thickness helps ensure that the aircraft can achieve the necessary aerodynamic efficiency, particularly in critical areas like near the fuel tank, where weight distribution and balance are also affected by ice and frost accumulation.

The other thickness options exceed this maximum limit, meaning that aircraft with frost beyond 1/8 inch would face elevated risks during operation due to an increase in drag and potential stall characteristics. Therefore, adhering to the 1/8 inch guideline is essential to ensure safe and efficient flight operations.