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

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Part I — Section 4, Chapter 5 I-4-5-5<br />

5.4.3.2 Non-aligned straight-in approach<br />

For a final approach where the track intersects the extended runway centre line, OCA/H varies according to the<br />

interception angle. The OCH <strong>of</strong> the procedure shall be equal to or greater than the lower limits shown in Table I-4-5-2.<br />

The calculations used to arrive at these values appear in the Appendix to this chapter. For nominal descent gradients<br />

above 5.2 per cent, increase by 18 per cent the lower limits shown in the table for each per cent <strong>of</strong> gradient above<br />

5.2 per cent.<br />

5.4.4 OCA/H for visual manoeuvring (circling)<br />

The OCA/H for visual manoeuvring (circling) shall provide the minimum obstacle clearance (MOC) over the highest<br />

obstacle in the visual manoeuvring (circling) area as specified in Table I-4-7-3 <strong>of</strong> Chapter 7. It shall also be:<br />

a) above the lower limits (also specified in Table I-4-7-3); <strong>and</strong><br />

b) not less than the OCA/H calculated for the instrument approach procedure which leads to the circling<br />

manoeuvre. See Chapter 7, “ <strong>Visual</strong> manouevring (circling) area”.<br />

Circling procedures are not provided for helicopters. When a helicopter instrument approach is followed by visual<br />

manoeuvring, the OCH shall not be less than 75 m (246 ft). See Chapter 7.<br />

5.4.5 MOC <strong>and</strong> OCA/H adjustments<br />

5.4.5.1 In certain cases the MOC <strong>and</strong>/or the OCA/H must be increased. This may involve:<br />

a) an additional margin that is added to MOC;<br />

b) a percentage increase in OCA/H; <strong>and</strong><br />

c) applying a lower limit (a minimum value) to OCA/H; as described below.<br />

5.4.5.2 Additional margin applied to MOC<br />

a) Mountainous areas. See 1.7, “Increased altitudes/heights for mountainous areas” in Section 2, Chapter 1 for<br />

guidance on increased MOC in mountainous areas.<br />

b) Excessive length <strong>of</strong> final approach. When a FAF is incorporated in a non-precision approach procedure, <strong>and</strong> the<br />

distance from the fix to the runway threshold for which the procedure is designed exceeds 11 km (6 NM), the<br />

obstacle clearance shall be increased at the rate <strong>of</strong> 1.5 m (5 ft) for each 0.2 km in excess <strong>of</strong> 11 km (0.1 NM in<br />

excess <strong>of</strong> 6 NM).<br />

5.4.5.2.1 Where a stepdown fix is incorporated in the final approach segment, the basic obstacle clearance may be<br />

applied between the stepdown fix <strong>and</strong> the MAPt, provided the fix is within 11 km (6 NM) <strong>of</strong> the runway threshold.<br />

5.4.5.2.2 These criteria are applicable to non-precision approach procedures only.<br />

23/11/06

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