Icing on airplane wings

Heavy in-flight icing on an airplane wing.

In-flight icing on the airplane wings can happen in several ways.

Ice accretion can occur before the anti- and de-icing systems are switched on and ice accretion is observed by small accretions on the leading edge.

More severe icing can occur, when the airplane encounters high liquid water content (LWC) clouds, which cause runback ice and ridge formation on the wings. These ice accretions can be located on different parts of the wings and is considered the most dangerous type of ice on the wings, because it dramatically changes the aerodynamic profile of the wing and decreases its lifting ability.

The third category contains irregularly shaped glaze ice accretion on random parts of the wings. These ice shapes are formed in longer contacts with icing conditions.

The frost formation on the ground during long standstills is the last category. Formed frost is usually dealt with by spraying de-icing chemicals on the wings, but untreated it can decrease the lifting ability of the wings.

During the flight, pneumatic boots (inflatable rubber membrane) have showed that they indeed can offer de-icing option on the wing. Although this system has its drawback, because it only offers ice removal for the protected part of the wing i.e. the leading edge. The others parts of the wing are vulnerable for the for example the runback icing or ridge formation. The runback ice on the wing can also be very harmful, because in the worst case it can decrease lift by 80 % significantly reducing aerodynamic performance.