The FMS position data uses three sources. Which are they?

The FMS position data uses three sources. Which are they?

• A. VHF, VOR/DME, GPS
• B. VHF, GPS, ADF
• C. VOR/DME, GPS, DME
• D. VHF, VOR, ILS

Answer: (A)

Position data in an FMS is kept reliable by combining multiple independent sources, so navigation remains accurate even if one source is degraded. The three sources used are VHF navigation signals (the VOR system), VOR/DME, and GPS. GPS provides precise latitude and longitude from satellites. VOR/DME adds another reference by giving both the bearing from a VOR VHF station and the distance to that station, allowing the system to determine position relative to known ground points. The VHF navigation signals offer additional coverage and cross-checks across the airspace, helping the FMS validate or supplement GPS and VOR/DME data. By integrating these three sources, the FMS achieves a robust position solution.

Position data in an FMS is kept reliable by combining multiple independent sources, so navigation remains accurate even if one source is degraded. The three sources used are VHF navigation signals (the VOR system), VOR/DME, and GPS. GPS provides precise latitude and longitude from satellites. VOR/DME adds another reference by giving both the bearing from a VOR VHF station and the distance to that station, allowing the system to determine position relative to known ground points. The VHF navigation signals offer additional coverage and cross-checks across the airspace, helping the FMS validate or supplement GPS and VOR/DME data. By integrating these three sources, the FMS achieves a robust position solution.