#1. Hoar frost occurs on airframe in clear air when the temperature of air frame is
Hoar frost forms when airframe temperature falls below the frost point.
#2. In clouds at temperatures below 0°C aircraft may encounter icing of the type
Icing may be intermediate between rime and glazed depending on cloud conditions.
#3. Opaque Rime ice is
Opaque rime ice is light and porous, formed by rapid freezing of small droplets.
#4. Rime is formed by freezing of ____ supercooled water droplets on airframe when air is flying through clouds
Rime forms by freezing of small supercooled droplets.
#5. Glazed ice is formed by freezing of _____ supercooled water droplets on airframe and aircraft is flying through clouds
Glazed ice forms from large supercooled droplets; freezing is slower and dense.
#6. The _____ ice poses serious aviation hazard
Glazed ice is dense, heavy, and hazardous for flight performance.
#7. Airframe icing occurs below 0°C. Its probability of occurrence decreases progressively to -20°C, as at lower temperatures the proportion of super-cooled water drops in a cloud
Probability decreases at lower temperatures due to fewer supercooled droplets.
#8. CI, CS and CC clouds consist mostly ice crystals, Icing hazard is therefore
Ice crystal clouds pose negligible icing hazard to aircraft.
#9. AS, NS consist of supercooled water drops and ice crystals in varying proportion icing is possible.
Icing in AS and NS clouds is usually light to moderate.
#10. In AC clouds _____ icing is possible in mountainous areas.
Moderate icing may occur in altocumulus clouds in mountains.
#11. In TCU icing may range from light to severe type at least up to _____ level.
TCU clouds may cause icing up to -20°C.
#12. In CB icing may range from light to severe type up to -20°C level. Below this temperature severe icing is
Below -20°C, supercooled water is limited, so icing is not significant.
#13. Liquid water content is an important factor in icing. As the maximum water concentration is around ______ , maximum ice formation in clouds may also be expected around the level.
Maximum ice formation occurs around -20°C where supercooled water is abundant.
#14. Carburetor icing occurs when air from intake passes through a ventury (choke) and causes expansional cooling and vaporization of fuel. Serious icing can occur at extreme temperatures.
Carburetor icing occurs between -10°C to 30°C under high humidity.
#15. ______ occurs in a moist cloudless air on an aircraft surface having temp, below 0°C, due to sublimation of water vapour onto feathery ice crystals.
Hoar frost forms by direct deposition of water vapour on cold surfaces.
#16. _____ occurs in St, Sc, Ac, Au, Cu, Ns at temperature -10 to -40°C and in Cb at temperature 20 to -40°C
Rime ice occurs in stratiform clouds and cumulonimbus over specified temperatures.
#17. In clouds _____ occurs when a wide range of water drop sizes are present at temperatures between 0°C and -40°C
Mixture forms when droplets of various sizes freeze differently.
#18. _____ occurs in AS, NS, AC and towering CU or CB between 0°C and -20°C, in warm front below 0°C, especially if the aircraft has rapidly descended from a colder region.
Glazed ice forms in mixed conditions with large droplets in clouds.
#19. When fog freezes on parked aircraft it produces
Frozen fog deposits cause hoar frost formation.
#20. Icing ____ the stalling speed appreciably
Icing increases stalling speed by disrupting airflow and adding weight.
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