IR.VI.B.K3FAA-S-ACS-8C · Nov 2023Knowledge
Ground-based and satellite-based navigation systems (orientation, course determination,...
Ground-based and satellite-based navigation systems (orientation, course determination, equipment, tests and regulations, interference, appropriate use of navigation data, signal integrity).
Bottom line
The GPS receiver verifies the integrity (usability) of the signals received from the GPS constellation through RAIM to determine if a satellite is providing corrupted information. In situations where the loss of RAIM capability is predicted to occur, the flight must rely on other approved equipment, delay departure, or cancel the flight.
Key numbers
| Number | What it means |
|---|---|
| ±4 degrees (test signal or surface checkpoint) | VOR ground check |
| 4 degrees maximum variation between systems | Dual VOR check |
| Minimum of four satellites above the mask angle | GPS satellites |
FAA references
- IFH ch. 9 (p. 9-31) — FAA-H-8083-15B
- IFH ch. 9 (pp. 9-26–9-27) — FAA-H-8083-15B
- 14 CFR 91.171 (VOR equipment check for IFR operations.) — eCFR current as of 2026-03-05
- 14 CFR 91.227 (Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment performance requirements.) — eCFR current as of 2026-03-05
- AC 90-105 Appendix J — AC No: 90-105A
- AC 90-105 Appendix E — AC No: 90-105A
- AC 90-105 Appendix A — AC No: 90-105A
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