The Effect of Wing Ice Contamination on Essential Flight Characteristics

Contamination of critical aerodynamic surfaces by ice, frost, and/or snow has been identified as the probable cause of a significant number of aircraft accidents. In most cases, the ice contamination has not been large ice accretions on the leading edges or thick layers of adhering snow on top of the wings. Rather, dangerous reductions in stall margins and handling qualities can occur because of ice related roughness equivalent to that of medium-grit sandpaper. Described here are the typical effects of such roughness on lift, drag, and pitching moment, and the corresponding effects on longitudinal and lateral control characteristics during rotation and liftoff. Of great importance is that the visual, aural, and tactical clues signaling a developing critical situation occur within a very few seconds, and usually do not correspond to any for which the flight crew has been trained or has previously experienced.