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ANNEX
POSITION FIXING ACCURACIES
1 Radar ^
1.1 Twentyfour miles should be considered as the maximum range for radar position
fixing in a routing system. This maximum range should be used with caution, reduced in
doubtful cases and only increased where local experience has positively determined a
greater distance.
1.2 The errors to be taken into consideration when assessing the fixing accuracy of a
radar should be
- ranging error 1.5%,
- bearing error ±1°.
2 Radio D.F. ^
2.1 Radio D.F. may supplement radar as a fixing device. In areas outside the effective
range of radar, D.F. is to be treated as the prime navigational aid and routes should be
designed to make the best use of D.F. taking into account its limitations, particularly
"coastal error".
2.2 The range and bearing error to be taken into consideration when assessing the
fixing accuracy of D.F. should be
- range as published in the Radio Aids to Marine Navigation,
- bearing error ±1°.
3 Echo Sounder ^
3.1 The design of the route should also take into consideration the practical use of an
echo sounder as a supplementary positional check.
3.2 The errors to be taken into consideration when assessing the accuracy of the echo
sounder should be
- ±1 metre on the shallow range scales,
- ±5 metre on the deep range scales, or
- ±5% of the indicated depth, whichever is the greater.
4 Visual Fixing ^
4.1 The routes should be designed so that the best use can be made of visual fixing as
a supplement to other methods.
4.2 The errors to be taken into consideration when assessing the accuracy of visual
bearings
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