McCann Aviation Weather Research, Inc. offers VVICE as an icing algorithm that incorporates the aerodynamic and meteorological variables. There are two parts to VVICE. 1) The meteorological part computes cloud liquid water (CLW) including convectively generated CLW. 2) The aircraft performance part computes an estimated performance loss which is based on the percent power increase (PPI) necessary to maintain speed and altitude after a five minute ice encounter.

Hit the red button below for a technical description of VVICE.

Aircraft Icing

To many pilots aircraft icing is one of the most dangerous inflight hazards. It can take down an airplane in a matter of minutes. If allowed to accumulate, ice will reduce aircraft performance by increasing drag and/or decreasing lift. Engineering studies on the icing hazard have identified many variables that influence how supercooled water accumulates as ice on aircraft surfaces. Listed below, the interaction between these variables is very complex. The most important is exposure time. Even a little ice will not disappear by itself and may act as a base for further accumulation. Therefore, a pilot must respond to any ice accumulation.

Aerodynamic and Meteorological Variables Affecting Aircraft Ice Accumulation

● Body size and shape
● Exposure time
● Droplet size distribution
● Angle of attack
● Flight speed
● Liquid water content

● Air temperature
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