Icing

Question 1

Trace

Answer 1

Ice becomes perceptible.
Rate of accumulation is slightly greater than rate of sublimation.
Not hazardous.
De-icing equipment used if encountered for over 60 minutes.

Question 2

Light

Answer 2

If flight prolonged in this environment for over 1 hour, rate of accumulation may become a problem.

Question 3

Moderate

Answer 3

The rate of accumulation is such that even short encounters become potentially hazardous.
Use of deicing or anti-icing equipment is necessary.

Question 4

Severe

Answer 4

Rate of accumulation is such that de-icing or anti-icing equipment fails to reduce or control the hazard.
Immediate diversion is necessary.