Icing intensity: trace, light, moderate & severe
Icing intensity is graded by ice accumulation rate, not feel (TC AIM MET 2.4, Table 2.3). PIREP /IC codes: TRACE, LGT, MOD, SEV.
| Intensity | Code | Hazard (by accumulation rate) | Action |
|---|---|---|---|
| Trace | TRACE |
barely perceptible; accumulates only slightly faster than it sublimates. Not hazardous unless in it over 1 hr | - |
| Light | LGT |
can become a problem if flight prolonged (over 1 hr) | - |
| Moderate | MOD |
even a short encounter potentially hazardous | use de-icing/anti-icing equipment or divert |
| Severe | SEV |
de-icing/anti-icing equipment fails to control it | divert immediately |
- Trace is an icing-only level; turbulence has none (
turbulence-intensity-and-reporting).
Trap: using de-icing equipment and continuing in severe icing: that is the moderate response.
References
- TC AIM MET 2.4 (icing intensity/accumulation-rate definitions, Table 2.3)