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

Part II — Section 1, Chapter 3 II-1-3-13
b) for glide path (elevation 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 (elevation angle) between 3.2° and 3.5°.
3.4.8.8.3.1.1 Procedures involving glide paths greater than 3.5° or any angle when the nominal rate of descent (Vat
for the aircraft type × 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.
3.4.8.8.3.1.2 Appendix B to Chapter 1 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-1-3-2) pressure altimeter 46 m
Correction for aerodrome elevation:
2 1 650
22 × × = 2.42 m
100 300
Correction for glide path angle:
5 3.5 – 3.2
22 × × = 3.30 m
100 0.1
Total correction 5.72 m rounded up to 6 m.
Corrected radio altimeter margin 22 + 6 = 28 m.
Corrected pressure altimeter margin 46 + 6 = 52 m.
3.4.8.8.3.2 Exceptions and adjustments to values in Table II-1-3-2. Values in Table II-1-3-2 are calculated to
account for a aircraft using normal manual overshoot procedures from OCA/H on the nominal approach path. The
values in Table II-1-3-2 do not apply to Cat III operations. The values do not consider the lateral displacement of an
obstacle nor the probability of an aircraft being so displaced. If consideration of these joint probabilities is required,
then the ILS CRM discussed in 3.4.9 shall be used. Values in Table II-1-3-2 may be adjusted for specific aircraft types
where adequate flight and theoretical evidence is available, i.e. the height loss value corresponding to a probability of
1×10 -5 (based on a missed approach rate of 10 -2 ).
23/11/06