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

I-2-2-4 Procedures — Aircraft Operations — Volume II
or d=0.033h(dinNM,hinthousandsoffeet).
For a cone angle of 50 degrees, the accuracy of entry is ± 5°. From the points of entry, tracking through the cone is
assumed to be achieved within an accuracy of ± 5°. Passage over the VOR is assumed to be indicated within the limits
of the cone of ambiguity. See Figure I-2-2-3. If the facility defines the MAPt or the turning point in the missed
approach, fixed values are used (see Section 4, Chapter 6, 6.1.6.1.2 and 6.4.6.2).
23/11/06
2.5.2 NDB
A cone effect area based upon an inverted cone of ambiguity extending at an angle of 40 degrees either side of the
facility should be used in calculating the areas. Entry into the cone is assumed to be achieved within an accuracy of
± 15° from the prescribed inbound track. From the points of entry, tracking through the cone is assumed to be achieved
within an accuracy of ± 5°. See Figure I-2-2-4. If the facility defines the MAPt or the turning point in the missed
approach, fixed values are used (see Section 4, Chapter 6, 6.1.6.2.1 and 6.4.6.2).
2.6 OPERATIONAL APPLICATION OF FIXES FOR FLIGHT PROCEDURE PLANNING
2.6.1 Minimum usable ground distance to a VOR/DME fix
The minimum usable ground distance to a VOR/DME fix can be determined from the following equations.
dm =hl tan 55°
where: hl = height above the facility in thousands of metres; and
dm = minimum usable DME ground distance in kilometers
or dm = 0.164 hl tan 55°
where: hl = height above the facility in thousands of feet; and
dm = minimum usable DME ground distance in nautical miles.
2.6.2 Initial/Intermediate approach fix
To be satisfactory as an intermediate or initial approach fix, the fix tolerance (along track tolerance (ATT) for RNAV)
must not be larger than ± 3.7 km (± 2.0 NM) with the following exception. When the FAF is a VOR, NDB or
VOR/DME fix, the fix tolerance may be increased to not greater than ± 25 per cent of the corresponding segment’s
length (intermediate or initial, as appropriate).
Example: If the intermediate or initial segment is 10 NM in length, then the fix tolerance may be 2.5 NM.
Measurements are made from the nominal fix positions along the nominal flight track. See Figure I-2-2-5.