What type of inspection is recommended for checking frost on an aircraft?

The recommended method for checking for frost on an aircraft is through a visual and tactile inspection of all critical surfaces. This approach involves visually examining the surfaces of the aircraft, such as the wings, tail, and control surfaces, for any visible signs of frost. Additionally, the tactile component involves physically feeling the surfaces to detect any irregularities or the presence of frost that may not be clearly visible, especially in low light conditions or when the frost is very light.

Frost can impair an aircraft's aerodynamic properties by altering the shape of critical surfaces, leading to potential safety issues during flight. Therefore, thoroughly inspecting these surfaces is crucial before the aircraft is deemed safe for operation. This method ensures that any frost present can be identified and addressed prior to takeoff, contributing to a safer flying experience.

In contrast, other inspection methods like auditory inspections, thermal inspections using infrared cameras, or solely relying on visual inspections may not adequately ensure all critical surfaces are free from frost. Auditory inspections are not effective for detecting frost, and while thermal inspections can provide some insights into temperature, they may miss spots where frost has formed. A sole visual inspection does not allow for the tactile confirmation needed to ensure all frost is identified, thereby leaving the aircraft potentially unsafe for flight.