To allow aircraft to maintain lift for take-off, all critical aircraft surfaces must be free of contaminants such as ice, frost or snow.

To allow aircraft to maintain lift for take-off, all critical aircraft surfaces must be free of contaminants such as ice, frost or snow.

• A. False
• B. Only in winter
• C. Only after de-icing
• D. True

Answer: (D)

Clean wing and control surfaces are essential for generating proper lift during takeoff. Ice, frost, or snow on these surfaces roughens the airfoil, disrupts the smooth flow of air, and can trip the boundary layer from laminar to turbulent at the wrong place. This causes earlier flow separation, increasing drag and raising the stall speed, which can lead to a loss of lift when you’re at the low speed and high angle-of-attack typical of takeoff. Because of this, all critical surfaces must be free of contaminants to maintain predictable lift and safe takeoff performance, and de-icing or anti-icing is required when conditions call for it. Contaminants matter whenever they’re present, not just in winter, and surfaces cannot be assumed clean after de-icing—they must be clean before departure.

Clean wing and control surfaces are essential for generating proper lift during takeoff. Ice, frost, or snow on these surfaces roughens the airfoil, disrupts the smooth flow of air, and can trip the boundary layer from laminar to turbulent at the wrong place. This causes earlier flow separation, increasing drag and raising the stall speed, which can lead to a loss of lift when you’re at the low speed and high angle-of-attack typical of takeoff. Because of this, all critical surfaces must be free of contaminants to maintain predictable lift and safe takeoff performance, and de-icing or anti-icing is required when conditions call for it. Contaminants matter whenever they’re present, not just in winter, and surfaces cannot be assumed clean after de-icing—they must be clean before departure.