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

I-4-3-8 Procedures — Aircraft Operations — Volume II
23/11/06
2) for base and procedure turns, however, the area for 165 km/h (90 kt) should be checked. An additional
template for these procedures is incorporated in the Template Manual for Holding, Reversal and Racetrack
Procedures (Doc 9371).
3.6.4.1 Statistical area construction
3.6.4 Area construction
If statistical methods are used to combine the variables and then to extrapolate distributions to develop areas, the
probability level associated with that extrapolation should meet an acceptable level of safety.
3.6.4.2 Additive tolerance area construction
A variety of methods may be used to construct areas. Whichever method is selected, the procedure design criteria
specified in 3.5, “Initial approach segment using a reversal procedure”, and the area parameters specified in 3.6.2,
“Area parameters”, apply. One additive tolerance method, the template tracing technique (TTT), is described in
Appendix C.
Note.— For applications where airspace is not critical, a method of constructing a simplified rectangular area
(based on the TTT areas) is also contained in Appendix C.
3.6.5 Area reduction
The area may be reduced under special circumstances. Methods of reduction include:
a) reduction of the maximum speed(s) specified for the procedure. Speeds below the minimum value for initial
approach in a given aircraft category shall not be specified (see Tables I-4-1-1 and I-4-1-2 of Section 4,
Chapter 1). If procedures are developed which exclude specific aircraft categories due to speed, this must be
stated explicitly;
b) restricting use of the procedure to specified categories of aircraft;
c) restricting procedure entry to specific track(s); and
d) use of DME or radial/bearing to limit outbound track (see 3.6.6, “Use of DME or intersecting radial/bearing”).
3.6.6 Use of DME or intersecting radial/bearing
If a DME distance or an intersecting radial or bearing is used to limit the outbound leg, the area may be reduced by
applying the appropriate adjustments described in Appendix C, in this case the limiting distance or radial/bearing shall
allow adequate time for the descent specified. The distance on the outbound track is thereby limited by the timing or by
reaching the limiting DME distance or radial/bearing, whichever occurs first.
3.6.7 Secondary areas
Secondary areas shall be added to the outer boundary of all areas calculated using the criteria in 3.6.4, “Area
construction”. The width of the secondary area is 4.6 km (2.5 NM).