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

Appendix B to Chapter 1
STEEP GLIDE PATH ANGLE APPROACHES
1. GENERAL
Glide path angles above 3.5° should be used in approach procedure design only for obstacle clearance purposes and
must not be used as a means to introduce noise abatement procedures. Such procedures are non-standard and require a
special approval.
2. PROCEDURE DESIGN
2.1 Obstacle clearance criteria
The following obstacle clearance criteria should be adjusted for specific glide path angle:
a) the W surface of the OAS;
b) origin of the Z surface of the OAS; and
c) height loss/altimeter margin (see paragraph 3).
W surface: Coefficient AW is determined by the formula
where θ is the glide path angle in degrees.
Coefficient CW = –6.45
2.2 Determination of the OAS coefficients
AW = 0.0239 + 0.0092 (θ –2.5)
X and Y surfaces: The X and Y surface coefficients for 3.5° glide path at the appropriate localizer/threshold distance
are used for all glide path angles greater than 3.5°.
Z surface: The coefficient Cz for the Z surface is determined by the formula
CZ =–AZ XZO
where AZ is the A coefficient for the selected missed approach gradient; and Xzo is the new co-ordinate of the Z surface
origin:
XZO = –900 – 50 (θ –3.5°)/0.1°
II-1-1-App B-1 23/11/06