PA.VI.D.K1FAA-S-ACS-6C · Nov 2023Knowledge
Methods to determine position.
Methods to determine position.
Bottom line
If GPS is installed, or a pilot has a portable aviation GPS on board, it can be used to determine the position and the location of the nearest airport. Without RAIM capability, the pilot has no assurance of the accuracy of the GPS position.
Key numbers
| Number | What it means |
|---|---|
| minimum of four satellites for an accurate three-dimensional position | GPS 3D fix |
| minimum of five satellites in view, or four satellites with a barometric altimeter (baro-aiding), to detect an integrity anomaly | RAIM detect |
| six satellites in view, or five satellites with baro-aiding, to isolate and remove a corrupt satellite signal | RAIM isolate |
FAA references
- PHAK ch. 16 (p. 16-34) — FAA-H-8083-25C (2023)
- PHAK ch. 16 (p. 16-31) — FAA-H-8083-25C (2023)
- AIM 5-3-2 (Position Reporting) — AIM Basic 2/20/25 w/ Change 1 (8/7/25) & Change 2 (1/22/26)
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