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

II-1-1-12 Procedures — Aircraft Operations — Volume II
where: ha = height of equivalent approach obstacle
23/11/06
hma = height of missed approach obstacle
θ = angle of glide path (elevation angle)
Z = angle of missed approach surface
x = range of obstacle relative to threshold (negative after threshold)
xz = distance from threshold to origin of Z surface (900 m (700 m Cat H))
1.4.8.8.3 Adjustment for high airfield elevations and steep glide path angles
1.4.8.8.3.1 Height loss (HL)/altimeter margins. The margins in Table II-1-1-2 shall be adjusted as follows:
a) for airfield elevation higher than 900 m (2 953 ft), the tabulated allowances shall be increased by 2 per cent of
the radio altimeter margin per 300 m (984 ft) airfield elevation; and
b) for glide path angles greater than 3.2° in exceptional cases, the allowances shall be increased by 5 per cent of
the radio altimeter margin per 0.1° increase in glide path angle between 3.2° and 3.5°.
1.4.8.8.3.1.1 Procedures involving glide paths greater than 3.5° or any angle when the nominal rate of descent (Vat
for the aircraft type x´ the sine of the glide path angle) exceeds 5 m/sec (1 000 ft/min), are non-standard. They require
the following:
a) increase of height loss margin (which may be aircraft type specific);
b) adjustment of the origin of the missed approach surface;
c) adjustment of the slope of the W surface;
d) re-survey of obstacles; and
e) the application of related operational constraints.
Such procedures are normally restricted to specifically approved operators and aircraft, and are associated with
appropriate aircraft and crew restrictions. They are not to be used as a means to introduce noise abatement procedures.
1.4.8.8.3.1.2 Appendix B shows the procedure design changes required and the related operational/certification
considerations.
Example: Aircraft Category C — Aerodrome elevation: 1 650 m above MSL; glide path angle 3.5°.
Tabulated allowances: radio altimeter 22 m
(Table II-1-1-2) pressure altimeter 46 m
Correction for aerodrome elevation:
2 1 650
22 × × =
2.42 m
100 300