Aircraft Operations. Volume II - Construction of Visual and Instrument ...

Chapter 4
VOR/DME RNAV
4.1 GENERAL
4.1.1 Area navigation systems which use the procedure must be controlled through a navigation database.
4.1.2 Reference facility. Criteria in this chapter apply to procedures based on one reference facility composed of a
VOR and collocated DME equipment. This facility shall be published.
4.2 VOR/DME RNAV SYSTEM USE ACCURACY
4.2.1 Accuracy
The operational performances of the area navigation equipment shall be such that the tolerances which determine the
system use accuracy remain within the values specified in 4.2.2 through 4.3 below. These values are based on 2 sigma
(95 per cent) confidence limits.
4.2.2 Navigation accuracy factors
The factors on which the navigation accuracy of VOR/DME RNAV depends are:
a) ground station tolerance;
b) airborne receiving system tolerance;
c) flight technical tolerance;
d) system computation tolerance; and
e) distance from the reference facility.
4.2.3 System use accuracies
4.2.3.1 The system use accuracy of the VOR is equal to the VOR system use accuracy of the facility not providing
track, which is equal to ± 4.5 degrees (see Part I, Section 2, Chapter 2).
4.2.3.2 The system use accuracy of the DME is equal to the DME system use accuracy (DTT) of the facility not
providing track, which is equal to ± (0.46 km (0.25 NM) + 1.25 per cent of the distance to the antenna). (See Annex 10,
Volume I, 3.5.3.1.3.2.)
4.2.3.3 For further information see Part I, Section I, Chapter 2, “Terminal area fixes”.
III-1-4-1 23/11/06