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

Part III — Section 3, Chapter 6 III-3-6-5
6.3.2 Intermediate approach segment alignment
The intermediate approach segment of a GBAS procedure shall be aligned with the final approach course.
6.3.3 Intermediate approach segment length
6.3.3.1 The optimum length of the intermediate approach segment is 9 km (5 NM) (Cat H, 3.7 km (2 NM)). This
segment shall allow interception with the final approach course and with the glide path.
6.3.3.2 The segment length should be sufficient to permit the aircraft to stabilize and establish on the final
approach course prior to intercepting the glide path, taking into consideration the angle of interception with the final
approach course.
6.3.3.3 Minimum values for distance between final approach and interception of the glide path are specified in
Table III-3-6-1; however, these minimum values should only be used if usable airspace is restricted. The maximum
length of the segment is governed by the requirement that it be located wholly within the service volume of the GBAS,
and normally at a distance not exceeding 37 km (20 NM) from the landing threshold point (LTP).
6.3.4 Intermediate approach segment area width
6.3.4.1 The total width at the beginning of the intermediate approach segment is defined by the total width of the
initial approach segment and tapers uniformly to match the horizontal distance between the OAS X surfaces at the FAP
(see 6.4.8.3, “Definition of OAS”).
6.3.4.2 For obstacle clearance purposes the intermediate approach segment is divided into a primary area bounded
on each side by a secondary area. However, when a DR track is used in the initial approach segment, the primary area
of the intermediate segment extends across the full width and secondary areas are not applied.
6.3.4.3 The primary area is determined by joining the primary initial approach area with the final approach
surfaces (at the FAP). At the interface with the initial approach segment the width of each secondary area equals half
the width of the primary area. The secondary area width decreases to zero at the interface with the final approach
surfaces. See Figure III-3-6-2.
6.3.4.4 Where a racetrack or reversal manoeuvre is specified prior to intercepting the final approach course, the
provisions in Part I, Section 4, Chapter 4, 4.4.4, “Turn not at the facility” apply, the facility being the GARP itself and
the FAF being replaced by the FAP. (See Figure III-3-6-3).
6.3.5 Intermediate approach segment obstacle clearance
The obstacle clearance is the same as defined in Part I, Section 4, Chapter 4, except where the procedure permits a
straight-in approach in which the aircraft is stabilized on the final approach course prior to crossing the IF. In this case,
obstacles in the secondary areas need not be considered for the purpose of obstacle clearance.
6.4 PRECISION SEGMENT
6.4.1 General
The precision segment for GBAS is aligned with the final approach course and contains the final descent for landing,
the initial and the intermediate missed approach. See Figure III-3-6-4.
23/11/06