Aircraft Escape Strategy from Supercooled Cloud Layers

Vertical profiles of liquid water in supercooled frontal stratiform clouds have been studied in order to estimate the potential rate of ice accretion at different levels within the cloud and to develop recommendations for escape strategies to avoid severe in-flight icing. The vertical soundings of the supercooled liquid clouds were obtained using the National Research Council of Canada Convair-580 equipped by Environment Canada for cloud microphysical measurements. The data were collected during five flight campaigns (CFDE 1, CFDE 3, AIRS 1, AIRS 1.5 and AIRS 2). In total 584 vertical LWC profiles were analyzed. A statistical summary has been prepared from the profiles of the potential thickness of accreted ice, liquid water content, temperature, and cloud depths. The maximum potential accreted thickness of ice does not exceed 2cm for a transit with a 3 degree glide slope thoughout the cloud depth. Based on the statistics, in order to avoid severe icing once significant icing is encountered, it is suggested that a climb or descent should be initiated. The aircraft should not stay at the same altitude within the cloud layer. I.