Surface contamination & the clean aircraft
The clean aircraft concept: you may not take off with frost, ice, or snow adhering to a critical surface (wings, control surfaces, stabilizers, propellers). This is the law, CAR 602.11(2), not just advice.
Why even thin frost matters: frost roughens the smooth upper wing, so it cuts lift and raises the stall speed and drag. A wing that looks only lightly frosted may not fly. Cold-soaked fuel can frost the upper wing even when the outside air is above freezing, so check for it.
Ground fluids (know de-ice vs anti-ice):
- Type I: heated and thin. It de-ices (removes frost, ice, or snow already there). Short holdover.
- Types II, III, IV: thickened. They anti-ice (stop new ice forming). Longer holdover.
Holdover time is how long the applied fluid protects the surfaces before precipitation overwhelms it. When it runs out, treat the wing again before takeoff.
Trap: a "little" frost is not acceptable. CAR 602.11 forbids any contamination adhering to a critical surface. Remove it all.
References
- CAR 602.11(1), (2)
- TP 1102 (Flight Training Manual)
- TC AIM AIR 2.12.2
- TP 10643 (When in Doubt... Small and Large Aircraft)