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IR.I.C.K2FAA-S-ACS-8C · Nov 2023Knowledge

Altitude selection accounting for terrain and obstacles, glide distance of airplane, IF...

ACS element text (the applicant demonstrates understanding of)

Altitude selection accounting for terrain and obstacles, glide distance of airplane, IFR cruising altitudes, effect of wind, and oxygen requirements.

Bottom line

In extreme cold or high pressure, height above ground and obstacles may be less than indicated.

Key numbers

Key numbers for Altitude selection accounting for terrain and obstacles, glide distance of airplane, IF...
NumberWhat it means
Below the MEA down to, but not below, the MOCA, provided the applicable navigation signals are availableMOCA descent
22 nautical miles from the VOR, based on the pilot's reasonable estimateVOR MOCA limit

FAA references

  1. RMH ch. 3 (p. 3-7) — FAA-H-8083-2A
  2. 14 CFR 91.177 (Minimum altitudes for IFR operations.) — eCFR current as of 2026-03-05
  3. IFH Glossary (p. G-12) — FAA-H-8083-15B
  4. 14 CFR 91.179 (IFR cruising altitude or flight level.) — eCFR current as of 2026-03-05
  5. IPH ch. 4 (p. 4-15) — FAA-H-8083-16B
  6. AFH ch. 18 (p. 18-4) — FAA-H-8083-3C
  7. AFH ch. 9 (p. 9-28) — FAA-H-8083-3C
  8. AFH ch. 15 (p. 15-14) — FAA-H-8083-3C
  9. 14 CFR 91.129 (Operations in Class D airspace.) — eCFR current as of 2026-03-05
  10. PHAK ch. 2 (p. 2-9) — FAA-H-8083-25C (2023)
  11. IPH ch. 1 (p. 1-20) — FAA-H-8083-16B
  12. IPH ch. 3 (p. 3-8) — FAA-H-8083-16B
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