Bearing Estimation

Bearing Estimation

A radial is a magnetic bearing from a VOR station.  In a conventional environment, the aircraft used to fly inbound and outbound on radials from the different VOR stations as defined by the ATS route network.

A position estimation can be made with the intersection of two radials.  As the angular signal propagates, the splay of the signal increases.  Therefore, the precision of the position estimation is a factor of distance from the transmitting stations; this is known as the Dilution of Precision (DOP).

Dilution of Precision

For angular measurements, the DOP is effected by range.

Using a simple mathematical rule, commonly called the 1 in 60 rule, the effect of angular displacement of the transmitted signal can be calculated.  The 1 in 60 Rule states:

‘An angle of 1° subtends 1NM at 60NM’

The performance of the transmitting station will clearly effect the accuracy of the position estimation. 


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