Weather

Question 1

Definition of icing conditions

Answer 1

‐​ Icing conditions exist when the OAT (on ground or after takeoff) or the TAT (in flight) is at or​below 10 °C and visible moisture in any form is present (such as clouds, fog with visibility of 1 sm​(1 600 m) or less, rain, snow, sleet or ice crystals).

​‐​ Icing conditions also exist when the OAT on the ground and for takeoff is at or below 10 °C and​operating on ramps, taxiways or runways where surface snow, standing water or slush may be​ingested by the engines, or freeze on engines, nacelles or engine sensor probes.

Question 2

Definition of severe ice acretion

Answer 2

Ice accretion is considered severe when the ice accumulation on the airframe reaches approximately​5 mm (0.2 in) thick or more.

Question 3

Definition of thin hoarfrost

Answer 3

Thin hoarfrost is typically a white crystalline deposit which usually develops uniformly on exposed​surfaces on cold and cloudless nights.​ It is so thin that surface features (lines or markings) can be distinguished beneath it.