The results presented in this paper were obtained in a statistical investigation made to determine the meteorological conditions of air temperature and stability under which the occurrence of aircraft icing is most likely to occur over the route flown by a scheduled air line in the Rocky Mountain region of southern British Columbia. The investigation was limited to the fall, winter and spring seasons.
The results obtained show that, during the seasons studied, the greatest frequency of icing occurs at temperatures in the vicinity of 8°F. and that air masses most favourable for icing are originally potentially unstable, which instability is realized when they are lifted over the higher terrain of the region considered. Icing may occur with lift of stable air provided the relative humidities of the lower levels are near 100 per cent.
* Published by permission of Dr. J. Patterson, controller of the Meteorological Service of Canada.