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AA.I.B.K6FAA-S-ACS-11A · Nov 2023Knowledge

Effects of icing on performance.

ACS element text (the applicant demonstrates understanding of)

Effects of icing on performance.

Bottom line

The degradation in aircraft performance and changes in flight characteristics when frozen contaminants are present are wide ranging, unpredictable, and highly dependent upon individual aircraft design.

Key numbers

Key numbers for Effects of icing on performance.
NumberWhat it means
up to 30 percent lift reduction, with contaminant thickness and roughness similar to medium or coarse sandpaper on the wing's leading edge and upper surfaceLift loss
40 percent drag increase, with contaminant thickness and roughness similar to medium or coarse sandpaper on the wing's leading edge and upper surfaceDrag increase

FAA references

  1. AC 20-117, para. 4a — AC No: 20-117
  2. AC 120-58 — AC 120-58
  3. AC 120-60, para. 10a — AC No: 120-60
  4. AC 135-17 — AC 135-17
  5. 14 CFR 91.527 (Operating in icing conditions.) — eCFR current as of 2026-03-05
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