Rho-theta is a term used in aviation navigation for a location method (or even a group of locating methods) based on the measurement of coordinates (direction and distance to a ground station beacon or beacons ). Many automated

Aids to Navigation Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual ma ...

, such as a

VORTAC Very high frequency omnirange station (VOR) is a type of short-range radio navigation system for aircraft, enabling aircraft with a receiving unit to determine its position and stay on course by receiving radio signals transmitted by a network ...

, use the ''Rho-Theta'' data as the primary method to calculate relative position of an aircraft to the reference beacon(s). ''Rho-Theta'' methodology is a key component in ''Area Navigation'' (RNAV). The term "Rho-Theta" consists of the two Greek letters corresponding to Rho and Theta: * Rho (Greek ρ) as a synonym for distance measurement, ''e.g.'' Rho would be the equivalent to the English abbreviation "R" for Range * Theta (Greek θ) for the associated heading (direction or bearing) measurement.

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Navigation {{Aviation-stub