What is the primary means of navigation in oceanic airspace?

• A. GPS
• B. VOR/DME
• C. ADF
• D. Inertial Navigation System

Answer: (A)

Global navigation satellite system positioning, specifically GPS, is the primary means of navigation in oceanic airspace. Over the oceans there are few or no ground-based navigation aids like VORs, DMEs, or NDBs, so pilots can’t rely on those signals for continuous position fixes. ADF depends on distant beacons and is not practical offshore, and VOR/DME requires ground stations whose coverage is limited over water. An inertial navigation system can operate without external signals, but it drifts over time and needs updates to stay accurate. GPS provides accurate, global position, velocity, and time anywhere there is satellite visibility, making it the standard method for enroute oceanic navigation.