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Question 1. Which of the following best describes why ice on a wing reduces lift? A) Ice adds weight, directly lowering lift. B) Ice changes the wing’s camber, decreasing the pressure differential. C) Ice smooths the surface, reducing skin friction drag. D) Ice increases the wing’s angle of attack automatically. Answer: B Explanation: Ice alters the airfoil shape, reducing camber and disrupting the smooth pressure distribution that generates lift. Question 2. The “Clean Aircraft Concept” primarily requires that an aircraft be: A) Free of any external fluids before take-off. B) Completely free of frozen contaminants on all aerodynamic surfaces prior to departure. C) De-iced only on the leading edges. D) Covered with anti-icing fluid at all times. Answer: B Explanation: Regulations mandate that no ice, frost, or snow remain on any aerodynamic surface before the aircraft is cleared for take-off. Question 3. Ice accretion most directly causes an increase in which aerodynamic parameter? A) Lift coefficient B) Drag coefficient C) Pitch moment D) Yaw stability Answer: B Explanation: Rough ice adds surface irregularities, raising the drag coefficient and reducing overall aerodynamic efficiency.
Question 4. When ice builds up on a control surface, the most immediate effect is: A) An increase in maximum lift. B) A reduction in the surface’s hinge moment. C) A delay in the surface’s response to pilot input. D) A decrease in aircraft weight. Answer: C Explanation: Ice disrupts airflow, causing control surfaces to become less responsive, which can delay or diminish control effectiveness. Question 5. The “cold soak” effect refers to: A) The rapid cooling of the aircraft skin during a snowstorm. B) Fuel in wing tanks cooling the wing structure enough to cause ice formation on exterior surfaces. C) The use of cold de-icing fluid to remove ice. D) The absorption of ambient cold by the aircraft’s electrical systems. Answer: B Explanation: Cold fuel can lower wing skin temperature below freezing, allowing ice to form even when ambient temperature is above 0 °C. Question 6. Hoarfrost differs from active frost primarily because hoarfrost: A) Forms from supercooled liquid droplets. B) Grows as a crystalline structure directly from water vapor on a surface below freezing. C) Is a type of ice pellet. D) Occurs only on the upper surfaces of wings. Answer: B
Explanation: Tactile inspection involves running a hand over surfaces to feel for thin, transparent ice that may not be readily visible. Question 10. Type I de-icing fluid is classified as a Newtonian fluid because: A) Its viscosity remains constant regardless of shear rate. B) It thickens when heated. C) It contains non-Newtonian polymers. D) It changes color with temperature. Answer: A Explanation: Newtonian fluids exhibit a constant viscosity independent of shear; Type I fluid behaves this way, allowing rapid flow for ice removal. Question 11. Which fluid type is primarily used for anti-icing rather than de-icing? A) Type I B) Type II C) Type V D) Type VI Answer: B Explanation: Type II (and III/IV) fluids are thickened, non-Newtonian fluids designed to remain on surfaces longer and prevent ice accumulation. Question 12. The typical color of Type I fluid is: A) Yellow B) Green C) Orange D) Blue Answer: C
Explanation: Type I de-icing fluid is conventionally orange, providing easy visual identification. Question 13. A glycol concentration of 40 % in a Type IV fluid primarily serves to: A) Increase the fluid’s freezing point. B) Reduce the fluid’s viscosity for faster application. C) Provide sufficient freeze-point depression to meet the 7 °C buffer requirement. D) Make the fluid biodegradable. Answer: C Explanation: Higher glycol concentrations lower the freezing point, ensuring a 7 °C safety buffer for Type IV anti-icing fluids. Question 14. The Lowest Operational Use Temperature (LOUT) for a de-icing fluid is: A) The temperature at which the fluid will no longer flow. B) The maximum temperature at which the fluid can be stored. C) The ambient temperature below which the fluid’s performance is not guaranteed. D) The temperature at which the fluid changes color. Answer: C Explanation: LOUT defines the lowest ambient temperature at which a fluid can be effectively applied while maintaining its designed performance. Question 15. For Type I fluid, the required freezing-point buffer is: A) 3 °C B) 5 °C C) 10 °C D) 15 °C
Answer: B Explanation: Higher precipitation rates accelerate ice buildup, reducing the effective holdover time. Question 19. Which factor most directly reduces the holdover time of a Type IV fluid? A) Low wind speed. B) High aircraft skin temperature. C) Strong jet blast from a nearby aircraft. D] Low ambient temperature. Answer: C Explanation: Jet blast can strip away the anti-icing film, shortening the holdover period. Question 20. If the holdover time expires before take-off, the required procedure is to: A] Continue taxiing to the runway. B] Apply a second layer of the same fluid without re-inspection. C] Re-apply the appropriate de-icing or anti-icing fluid and obtain a new HOT. D] Request a runway extension. Answer: C Explanation: Once HOT expires, a fresh application is mandatory to ensure safety, and a new holdover time must be calculated. Question 21. The “One-Step Procedure” for ice removal consists of: A) Applying Type I fluid, waiting, then applying Type II fluid. B] Applying a combined de-icing/anti-icing fluid that both removes ice and leaves a protective coating in a single pass.
C] Using hot water followed by a dry-ice blast. D] Performing a tactile inspection after a single spray. Answer: B Explanation: One-step combines de-icing and anti-icing in one application, using a fluid formulated for both actions. Question 22. In the “Two-Step Procedure,” the purpose of the second step is to: A] Heat the wing surface after de-icing. B] Apply a thickened anti-icing fluid that remains on the surface after the ice has been removed. C] Remove remaining fluid residues. D] Cool the aircraft for better fuel efficiency. Answer: B Explanation: After Type I removes ice, a thickened Type II/IV anti-icing fluid is applied to protect the surfaces during taxi and take-off. Question 23. The correct spray pattern for wing de-icing starts at: A] The trailing edge and moves forward. B] The wing root and moves outward. C] The leading edge and proceeds aft. D] The tip and moves inward. Answer: C Explanation: Initiating at the leading edge ensures that ice is removed from the most critical aerodynamic area first. Question 24. Symmetrical application of de-icing fluid is essential because: A] It reduces the amount of fluid needed.
B] At a 45-degree angle to the fuselage, avoiding the nose gear. C] Parallel to the runway, at a distance that prevents spray from reaching the flight-deck windows. D] Directly over the wing’s upper surface. Answer: C Explanation: Proper boom placement minimizes spray intrusion into the cockpit and protects sensitive components. Question 28. Personal Protective Equipment (PPE) required for de-icing crew includes: A] Only safety glasses. B] Respiratory protection, eye protection, and slip-resistant footwear. C] Hearing protectors and reflective vests only. D] Fire-resistant suits. Answer: B Explanation: Glycol-based fluids can be irritating; crew need respiratory masks, goggles, and slip-resistant shoes for safety. Question 29. Environmental regulations concerning de-icing fluids most commonly require: A] Immediate disposal of used fluid into the drainage system. B] Recovery and recycling of glycol to prevent runoff contamination. C] Burning of excess fluid on site. D] Storage of fluid at ambient temperature for 30 days. Answer: B Explanation: Glycol is a pollutant; many jurisdictions mandate collection and reclamation to protect water sources.
Question 30. Standardized phraseology used between the de-icing operator and the flight deck typically includes: A] “Ready for take-off”. B] “De-icing complete, holdover time X minutes”. C] “Engine start approved”. D] “Fuel check complete”. Answer: B Explanation: The operator must communicate the completion of de-icing and the calculated holdover time to the crew. Question 31. After de-icing, the final visual check must confirm that: A] All fluid residues have been completely removed. B] No ice or frost remains on any aerodynamic surface. C] The aircraft weight has not increased. D] The windshield wipers are operational. Answer: B Explanation: The post-de-icing inspection verifies that the aircraft is free of any frozen contaminants before taxi. Question 32. The anti-icing verification check primarily ensures: A] That the fluid color matches the required specification. B] That a uniform protective layer covers all required surfaces. C] That the fluid temperature is above freezing. D] That the fluid has been mixed with water correctly. Answer: B Explanation: Uniform coverage guarantees consistent protection against ice accumulation during the holdover period.
Question 36. The primary aerodynamic consequence of a reduced stall angle of attack due to ice is: A] Increased climb performance. B] Lower stall speed. C] Earlier onset of stall during take-off or landing. D] Enhanced maneuverability. Answer: C Explanation: Ice changes the airfoil shape, causing the stall to occur at a lower angle of attack, which can happen unexpectedly during critical phases. Question 37. Which of the following is a non-Newtonian fluid characteristic of Type II/IV fluids? A] Viscosity remains constant regardless of shear rate. B] Viscosity decreases when the fluid is sheared (thins). C] Viscosity increases when the fluid is sheared (thickens). D] Viscosity is temperature-independent. Answer: B Explanation: Type II/IV fluids are shear-thinning; they become less viscous under high shear (spraying) but thicken once applied, forming a protective film. Question 38. A fluid’s “freezing-point buffer” is defined as: A] The difference between the fluid’s freezing point and the ambient temperature at which it is applied. B] The temperature at which the fluid changes color. C] The time it takes for the fluid to evaporate. D] The margin between the fluid’s LOUT and the aircraft’s skin temperature. Answer: A
Explanation: The buffer ensures the fluid remains liquid under expected temperature conditions, providing a safety margin. Question 39. In heavy precipitation, which of the following most significantly reduces holdover time? A] Low humidity. B] High wind velocity over the aircraft. C] Low wing skin temperature. D] Increased jet blast from nearby traffic. Answer: D Explanation: Jet blast can strip the anti-icing film, dramatically shortening the effective holdover period during heavy precipitation. Question 40. The correct sequence when performing a two-step de-icing operation is: A] Apply Type II, wait, then apply Type I. B] Apply heated Type I to remove ice, then immediately apply cold Type II/IV anti-icing fluid. C] Apply Type IV only. D] Apply Type I twice. Answer: B Explanation: The first step removes existing ice; the second step provides protection against further accumulation. Question 41. Which component is most vulnerable to fluid contamination during de-icing? A] Horizontal stabilizer. B] Pitot-static system. C] Aileron hinge.
B] Light rain with ambient temperature at –2 °C. C] Heavy snow with wind gusts of 30 kt. D] Dense fog with ambient temperature of +5 °C but wing fuel temperature at – 10 °C. Answer: D Explanation: Even though ambient temperature is above freezing, cold fuel can cause wing skin to be below freezing, necessitating a cold-soak evaluation. Question 45. The “freeze-point buffer” for Type III fluid is: A] 5 °C. B] 7 °C. C] 10 °C. D] 12 °C. Answer: B Explanation: Both Type II and Type IV fluids require a 7 °C buffer; Type III, being a non-Newtonian anti-icing fluid, follows the same requirement. Question 46. Which of the following is NOT a factor that influences the effectiveness of anti-icing fluid? A] Ambient temperature. B] Fluid concentration. C] Aircraft tail number. D] Wind speed. Answer: C Explanation: The aircraft’s registration does not affect fluid performance; temperature, concentration, and wind are critical variables.
Question 47. When a de-icing vehicle is operating in low-visibility conditions, the crew must: A] Increase spray pressure to compensate. B] Use audible signals and maintain a safe distance from the aircraft’s prop wash. C] Disable the boom to avoid accidental contact. D] Turn off all lights to avoid glare. Answer: B Explanation: In low visibility, communication and safe positioning become essential to prevent collisions and ensure proper application. Question 48. The “anti-icing verification check” should be performed: A] Before the first de-icing fluid is applied. B] Immediately after the final fluid application and before taxi. C] Only after the aircraft has taken off. D] During the flight crew’s pre-flight briefing. Answer: B Explanation: Verification occurs after the protective fluid is applied, confirming coverage before the aircraft moves. Question 49. A “dry-run” during a de-icing operation refers to: A] Spraying water without any fluid to test the boom. B] Performing the spray pattern without actually applying fluid, to verify coverage. C] Removing all fluid after application. D] Using a dry ice blast instead of glycol. Answer: B Explanation: A dry-run checks the spray pattern and coverage without expending fluid, ensuring proper technique.
Explanation: Ice on the trailing edge disrupts the smooth pressure recovery, leading to early flow separation and loss of lift. Question 53. In the context of de-icing, “shear-thinning” refers to: A] The fluid becoming more viscous when sprayed. B] The fluid’s viscosity decreasing under high-speed spray, allowing efficient application. C] The fluid solidifying upon contact with ice. D] The fluid’s temperature dropping during application. Answer: B Explanation: Shear-thinning fluids reduce viscosity when subjected to shear forces (spraying), facilitating rapid coverage. Question 54. Which of the following statements about “active frost” is correct? A] It forms only on aircraft that have been in flight for more than two hours. B] It is the result of water droplets freezing on contact with a sub-freezing surface. C] It is a type of ice that can be removed with a simple hand wipe. D] It is indistinguishable from hoarfrost. Answer: B Explanation: Active frost occurs when supercooled droplets impact a surface below freezing, instantly forming a thin ice layer. Question 55. The most effective way to prevent fluid runoff into the airport drainage system is to: A] Apply fluid only to the wing tips. B] Use containment pads and collect all runoff for glycol recovery. C] Increase the spray pressure to reduce overspray. D] Apply fluid during rain.
Answer: B Explanation: Containment and recovery systems capture runoff, complying with environmental regulations and preventing pollution. Question 56. During a tactile pre-step inspection, a “soft, waxy” feel on the wing surface most likely indicates: A] Clean metal. B] Light frost that can be brushed off. C] Thick ice that requires de-icing. D] Residual fluid from a previous operation. Answer: B Explanation: Light frost often feels waxy and can be removed with a gentle brush, indicating minimal contamination. Question 57. The primary reason for applying anti-icing fluid at a colder temperature than the ambient air is: A] To ensure the fluid freezes on the surface. B] To increase the fluid’s viscosity for better adhesion. C] To create a thicker protective layer that resists immediate freezing. D] To reduce the amount of fluid needed. Answer: C Explanation: Cooler fluid remains on the surface longer and provides a more robust barrier against ice formation. Question 58. Which of the following best explains why a higher glycol concentration raises a fluid’s LOUT? A] Higher glycol lowers the fluid’s viscosity, allowing it to be sprayed at lower temperatures.
