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

II-3-1-App A-2 Procedures — Aircraft Operations — Volume II
23/11/06
4. CONSTRUCTION OF AREAS FOR VOR AND NDB ROUTES
4.1 VOR
4.1.1 Constant width starting abeam the facility. In Annex 11, Attachment A, values are indicated for the width of
ATS routes navigated by VOR. Abeam the facility, values of ± 7.4 km (4 NM) and ± 11.1 km (6 NM) correspond
respectively to 95 per cent and 99.7 per cent of probability of containment. The first value is specified for the limits of
the primary area; the second value plus an additional value of 3.7 km (2.0 NM) is applied for the limits of the
secondary area.
4.1.2 Angular limits. For distances greater than 70 km (38 NM) from the facility, the angular tolerances will cause
the area width to increase. (See Figure II-3-1-App A-1.)
4.2 NDB
4.2.1 Constant width starting abeam the facility. To determine the width of the areas abeam the NDB, a factor of
1.25 is applied to the values specified in the VOR case, as in Part II, Section 2, Chapters 2 and 3. The resulting values
are ± 9.3 km (5.0 NM) and ± 18.5 km (10.0 NM). (See Figure II-3-1-App A-2.)
4.2.2 Angular limits. For distances greater than 60 km (32 NM) from the facility, the angular tolerances will cause
the area width to increase. (See Figure II-3-1-App A-2.)
4.3 Protection areas associated with turns
4.3.1 Turns can be executed overhead a facility or at a fix.
4.3.2 Turn parameters. The turn is constructed based on the parameters specified in Chapter 1, 1.4.3.3, “Turn
parameters” and the following additional parameters:
a) maximum pilot reaction time: 10 s; and
b) bank establishment time: 5 s.
4.3.3 The turn area is constructed as follows (see Figures II-3-1-App A-3 and II-3-1-App A-4):
a) on the outer edge of the turn, a wind spiral is constructed at the limit of the primary area and starting at a
distance after the nominal turn point corresponding to the fix tolerance plus 15 seconds of flight at the nominal
TAS plus a maximum tail wind. (See Part I, Section 2, Chapter 3 for the construction of the wind spiral); the
convergence angle after the turn is 30°; the secondary area width is constant throughout the turn; and
b) on the inner edge of the turn, the primary area splays from a point located at a distance equal to r*tan (α/2) prior
to the fix tolerance of the nominal turn point, at an angle of half the angle of turn. The secondary area width is
constant during the turn.
If on one edge of the turn, the convergence angle cannot be used because the area of the segment being entered
is already too wide, a splay angle of 15° is applied instead, measured from the nominal track of the segment
being entered (see Figure II-3-1-App A-4).