Air Frame Icing Influences on the Risk of Loss of Control In-flight

Abstract

Although icing is covered in significant detail in flight training, often the subtle influences of icing on wing performance are not well understood in the world of commercial flight operations. In certain conditions, protection systems and escalating advisories to enhance stall prevention by the pilot can be reduced, or eliminated, due to the aerodynamic performance variations of the wing as a result of ice-altered angle of attack. In response to this unusual wing performance characteristic, the risk of loss of control in-flight (LOC-I) can be significantly elevated in certain conditions. With LOC-I continuing to consistently demonstrate itself as the leading lethal threat to air safety in aviation despite traditional unusual attitude training philosophies, associated procedures and regulatory requirements, the aviation training community must continue to evolve pilot knowledge, skill and awareness. The counter-intuitive nature of a meaningful all-attitude/all-envelope awareness, prevention and recovery skill development, to counter LOC-I conditions, poses training challenges as the industry looks to the future. This study will provide a brief outline of the aerodynamic influences of icing on airplane performance specifically related to angle of attack variations on jet and turbo prop airplanes. Performance charts will be presented to highlight the direct influence airplane icing has on reducing, in some cases eliminating, the pilots ability to be aware of an approaching stall and, at times, prevent the onset of the full stall in hazardous flight conditions. Mitigations will be outlined that allow pilots, through knowledge and skills training, to readily diagnose, prevent and, if necessary, recover airplanes from inadvertent upset and stall events due to reduced main wing angle of attack as result of icing conditions.