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NEHC Newsletter Quiz Fall 20091.) Regarding rime ice, it: A. forms when water drops are large as in rain or cumuliform clouds. B. forms when water drops are small such as in stratified clouds or drizzle. C. is hard, heavy and easily removed by deicing equipment. D. decreases aerodynamic efficiency of the airfoil, is brittle, and more difficult to remove than clear ice. 2.) Regarding clear ice, it: A. forms when water drops are large as in rain or cumuliform clouds. B. forms when water drops are small such as in stratified clouds or drizzle. C. is hard, heavy and more easily removed by deicing equipment than rime ice. D. decreases aerodynamic efficiency of the airfoil, is brittle, and difficult to remove. 3.) Which statement is most correct pertaining to in flight icing hazards? A. When the temperature is at or near 0º C, pilots can normally expect to encounter clear ice in stratus clouds. B. When the temperature is at or near 0º C, pilots can normally expect to encounter rime ice in stratus clouds. C. When the temperature is at or near 0º C, pilots can normally expect to encounter mixed ice in stratus clouds. D. When the temperature is at or near 0º C, pilots can normally expect that there will be little or no ice accretion while flying in stratus clouds. 4.) A condition favorable for rapid accumulation of clear ice is freezing rain below a frontal surface. A. True. This hazard is only associated with a warm front. B. True. This hazard may occur with either a warm front or cold front. C. True. The best way to escape from such an icing encounter is to descend to warmer air at, or close to, the surface. D. True. This hazard is only associated with a cold front. 5.) According to the Aeronautical Information Manual, which of the following statements best describes an encounter with moderate icing conditions? A. The rate of accumulation may create a problem if flight is prolonged in this environment (over 1 hour). Occasional use of deicing/anti-icing equipment removes/prevents accumulation. It does not present a problem if the deicing/anti-icing equipment is used. B. Ice becomes perceptible. Rate of accumulation is slightly greater than sublimation. Deicing/anti-icing equipment is not utilized unless encountered for an extended period of time (over 1 hour). C. The rate of accumulation is such that deicing/anti-icing equipment fails to reduce or control the hazard. Immediate flight diversion is necessary. D. The rate of accumulation is such that even short encounters become potentially hazardous and use of deicing/anti-icing equipment or flight diversion is necessary. 6.) You are flying a piston powered helicopter with a carbureted engine. Induction system icing is: A. Not a concern. The heat generated by engine case is sufficient to prevent carburetor icing. B. Carburetor ice forms when the temperature in the engine intake drops below freezing and sufficient moisture is present for sublimation. C. Induction icing varies greatly among different aircraft and is primarily an engineering and operating problem rather than meteorological. D. B and C are correct. Induction icing always lowers engine performance and can even reduce intake below that necessary for the engine to operate. 7.) You are climbing to your cleared cruise altitude and note that the free air temperature is 0º C as you enter cumuliform clouds. Shortly after entering the clouds you notice the airspeed increasing. You have been maintaining a constant pitch attitude and did not change the power setting. What is one possible reason for the airspeed increase and what action should you take? A. Cold, moist air is denser than warm, dry air. It’s not unusual for an aircraft climbing in such conditions to experience an increase in performance. The correct course of action is to pitch the nose up to reduce airspeed. B. This sounds like the static source is blocked, probably caused by water entering the static port. When the static source is blocked airspeed increases as the aircraft climbs and decreases as the aircraft descends. Activate the alternate static source. C. This sounds like a clogged pitot source, probably caused by the pitot tube being iced over. When the pitot tube and its drain are clogged and the static source is not restricted, airspeed increases as the aircraft climbs and decreases as the aircraft descends. Check that the pitot heater is on and operational. D. This sounds like both the pitot and static sources have been blocked, probably caused by inflight icing. When the pitot and static systems become blocked the airspeed indicator acts like an altimeter, the altimeter reads sea level and the vertical speed indicator shows the aircraft descending until the altimeter reaches sea level then shows that the aircraft is in level flight, regardless of whether the aircraft is climbing or descending. 8.) Icing is more probable and more hazardous in mountainous regions than over other terrain. A. True. The most dangerous icing takes place above the crests and to the windward side of the ridges and will extend 5,000 feet or higher above the tops of the mountains. B. True. The most dangerous icing takes place at the crest and to the leeward side of the ridges and will extend above the tops of the mountains. C. True. But in order for the icing encounter to be dangerous to most aircraft cumuliform clouds must be present. D. True. But in order for the icing encounter to be dangerous to most aircraft stratiform clouds must be present. 9.) You overhear an aircraft giving an icing PIREP to ATC. The pilot reports that clear ice is accumulating on the aircraft. Based on this report, what is the pilot observing on the aircraft? A. Ice, sometimes clear and smooth, but usually containing some air pockets, which results in a lumpy translucent appearance. B. A rough, milky, opaque ice formed by the rapid freezing of supercooled drops/droplets after they strike the aircraft. C. Ice which forms from the freezing or refreezing of water leaving protected surfaces and running back to unprotected surfaces. D. Actual ice observed visually to be on the aircraft by the flight crew or identified by on-board sensors. 10.) The National Weather Service has developed CIP (Current Icing Product), a weather product that provides a graphical view of the current icing environment. Web address http://adds.aviationweather.gov/icing/icing_nav.php Pilots who use CIP do not need to concern themselves with SIGMETS or AIRMETS related to icing. A. True. B. False. Input from weather sensors is provided to software models to produce this automatically generated graphical weather product. The CIP is updated hourly, and provides current information via icing severity graphics and icing probability graphics. It is important to note that all CIP products are not forecasts, but presentations of current conditions at the time of the analysis ("Nowcast" information). CIP is not to be used as a forecast for icing conditions.
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