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

III-3-4-6 Procedures — Aircraft Operations — Volume II
for gradients of 3, 4 and 5 per cent. It is bounded laterally by the LNAV primary area. The lower/inner edges of the
associated side surfaces are defined by the edges of the LNAV missed approach primary area and the outer edges of the
LNAV secondary areas 50 m above the final missed approach (Zf) surface.
4.3.5.4.2.1 Calculation of the start of the final missed approach surface (XZf)
23/11/06
XZf =(MOCapp – RDH) / tan VPA – ATT – d – X + (MOCapp – 50) / tan Z
4.3.6 Termination of the APV segment. The APV segment terminates at the MAPt if a turn is specified at the
MAPt, at the MATF or the MAHF, whichever is earliest.
4.3.7 Determination of minimum promulgated temperature. Determine the minimum probable temperature and
round it down to the next lower 5°C increment. Use this value to calculate the minimum VPA and the final approach
surface (see 4.3.5 and 4.5.2). The resulting minimum VPA shall not be less than 2.5° at this temperature. If necessary,
the published VPA shall be increased to achieve this minimum angle.
4.4.1 Minimum obstacle clearance (MOC)
4.4 DETERMINATION OF OCH FOR APPROACH AND
MISSED APPROACH OBSTACLES
a) The MOC in the final approach (MOCapp) is 75 m. It shall be increased in accordance with the provisions of
Part I, Section 4, Chapter 5, 5.4.6.2 a) and b), regarding increased margins for excessive length of the final
approach, and for mountainous areas.
b) The MOC in the missed approach (MOCma) is 30 m for the intermediate and 50 m for the final missed approach.
This margin is included in the construction of the Zi and Zf surfaces, which start at XZi and XZf.
4.4.2 Approach and missed approach obstacles. Accountable obstacles are those penetrating the APV-OAS. They
are divided into approach and missed approach obstacles as follows.
4.4.2.1 The simplest method is by range: approach obstacles are those between the FAP and XZi, andmissed
approach obstacles are those after XZi. However in some cases this may produce an excessive penalty for certain missed
approach obstacles (see Attachment to Part II, 1.9). Where desired by the appropriate Authority, missed approach
obstacles may be defined as those above a plane parallel to the plane of the vertical path and with origin at XZi (See
Figure III-3-4-7), i.e. obstacle height greater than [(XZi +x)tanVPA].
4.4.3 Calculation of OCA/H within the APV segment. OCA/H calculation involves a set of obstacle assessment
surfaces (APV-OAS). If the APV-OAS are not penetrated, the OCA/H is defined by the lower limit of 75 m or 90 m
(see 4.2.2 b)). However, if the APV-OAS are penetrated, the MOCapp (adjusted for side surface penetrations if
appropriate) is added to the height of the highest approach obstacle, or the adjusted height of the largest missed
approach penetration, whichever is greater. This value becomes the OCA/H.
4.4.3.1 First, determine the height of the highest approach obstacle penetrating the FAS or the horizontal plane as
identified in 4.4.2. Next, reduce the heights of all missed approach obstacles to the height of equivalent approach
obstacles by the formula given below:
ha = hma cot Z + (X – Xz)
cot z + cot VPA