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

Part III — Section 3, Chapter 6 III-3-6-17
6.5.3.3.4 Obstacle clearance. Obstacle elevation/height shall be less than:
(OCA/Hps –HL)+do tanZ–MOC
where: do =dz + shortest distance from obstacle to line K-K,
and MOC is:
dz = horizontal distance from SOC to the earliest TP,
50 m (164 ft) (Cat H, 40 m (132 ft)) for turns more than 15° and
30 m (98 ft) for turns 15° or less.
If the obstacle elevation/height exceeds this value, the OCA/H must be increased, or the TP moved to obtain the
required clearance (see Part II, Section 1, Chapter 1, Appendix A).
6.6 SIMULTANEOUS ILS AND/OR MLS PRECISION
APPROACHES TO PARALLEL OR NEAR-PARALLEL
INSTRUMENT RUNWAYS
Note.— Guidance material is contained in the Manual on Simultaneous Operations on Parallel or Near-Parallel
Instrument Runways (Doc 9643).
6.6.1 General
When it is intended to use precision approach procedures to parallel runways simultaneously, the following additional
criteria shall be applied in the design of both procedures:
a) the maximum intercept angle with the final approach course approach track is 30°. The point of intercepting the
final approach track course should be located at least 3.7 km (2.0 NM) prior to the point of intercepting the
glide path;
b) the minimum altitudes of the intermediate segments of the two procedures differ by at least 300 m (1 000 ft);
and
c) the nominal tracks of the two missed approach procedures diverge by at least 30°, the associated missed
approach turns being specified as “as soon as practicable” which may involve the construction of (a) missed
approach procedure(s).
A single GBAS is capable of serving both runways, however, a separate safety study needs to be carried out when it
is intended to use GBAS for both runways.
6.6.2 Obstacle clearance
The obstacle clearance criteria for precision approaches, as specified in the designated chapters, apply for each of
the parallel precision procedures. In addition to these criteria a check of obstacles shall be made in the area on the side
opposite the other parallel runway, in order to safeguard early turns required to avoid potential intruding aircraft from
the adjacent runway. This check can be made using a set of separately defined parallel approach obstacle assessment
surfaces (PAOAS). An example of a method to assess obstacles for these procedures is included in Part II, Section 1,
Chapter 1, Appendix D.
23/11/06