ATR 42-500  (Copyright © Aroosh Naqvi)

ATR, like most turboprop aircraft, flies at lower levels where moisture and temperatures are ideal, icing is one of the aircraft's biggest drawbacks. As illustrated here, the aircraft is passing through a lot of moisture which upon contact with the aircraft skin freezes when the temperatures are near the freezing point

ATR 42-500  (Copyright © Aroosh Naqvi)

Hi shutter speed to freeze the prop shows ice begin to accumulate on the leading edge of the prop blades as well

ATR 42-500  (Copyright © Aroosh Naqvi)

The initial ice buildup on the wing leading edge, spinner and engine intake

ATR 42-500  (Copyright © Aroosh Naqvi)

The ATR is equipped with two defenses against ice. Anti-Ice, which as the name suggest is there to prevent the development of ice primarily by heating areas particularly susceptible to ice accretion. This is the first defense, the second being De-Icing, which as the name suggests involves the removal of ice one it has accumulated on the aircraft. De-icing is usually done through the use of inflatable rubber boots which expand thereby breaking the ice. This can clearly be seen in this image as alternative areas of the boots on the wing leading edge expand causing the ice to crack and fall off