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IR.I.C.K1dFAA-S-ACS-8C · Nov 2023Knowledge

d. Primary and alternate airports

ACS element text (the applicant demonstrates understanding of)

Route planning, including consideration of: d. Primary and alternate airports

Bottom line

Unless otherwise authorized by ATC, each person filing an IFR flight plan must include an alternate airport, except as provided in 14 CFR 91.169(b).

Key numbers

Key numbers for d. Primary and alternate airports
NumberWhat it means
800 ft ceiling / 2 sm visibility, aircraft other than helicoptersNonprecision alt
Ceiling 200 ft above approach minimum, visibility at least 1 sm but never less than approach minimumHelicopter alt

FAA references

  1. 14 CFR 91.169 (IFR flight plan: Information required.) — eCFR current as of 2026-03-05
  2. IPH ch. 4 (p. 4-6) — FAA-H-8083-16B
  3. PHAK ch. 16 (p. 16-34) — FAA-H-8083-25C (2023)
  4. IFH ch. 1 (p. 1-27) — FAA-H-8083-15B
  5. PHAK ch. 2 (p. 2-18) — FAA-H-8083-25C (2023)
  6. IFH ch. 9 (pp. 9-28–9-29) — FAA-H-8083-15B
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