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IR.II.B.R3FAA-S-ACS-8C · Nov 2023Risk management

Modes of flight and navigation instruments, including failure conditions.

ACS element text (the applicant demonstrates understanding of)

Modes of flight and navigation instruments, including failure conditions.

Bottom line

In the event of a WAAS failure, WAAS avionics revert to GPS-only operation which is equivalent in function to unaugmented GPS avionics and satisfies the requirements for IFR use of GPS.

FAA references

  1. AFH ch. 18 (pp. 18-14–18-15) — FAA-H-8083-3C
  2. IFH ch. 11 (p. 11-8) — FAA-H-8083-15B
  3. AC 90-100 Appendix 2 — AC No: 90-100A
  4. IFH ch. 5 (p. 5-19) — FAA-H-8083-15B
  5. AFH ch. 2 (p. 2-22) — FAA-H-8083-3C
  6. PHAK ch. 8 (p. 8-2) — FAA-H-8083-25C (2023)
  7. AC 90-100, para. 10d — AC No: 90-100A
  8. AC 90-105 Appendix H — AC No: 90-105A
  9. AC 90-107, para. 7a — AC No: 90-107
  10. 14 CFR 91.205 (Powered civil aircraft with standard U.S. airworthiness certificates: Instrument and equipment requirements.) — eCFR current as of 2026-03-05
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