getting to grips with CAT II CAT III operations(39)

The wind characteristics are longitudinal and lateral component, nominal wind shear and turbulence.
The runway characteristics are elevation, slope, length, ambient temperature and status (dry or wet). Auto-land is generally approved by JAA only up to 2500 ft runway elevation, unless a runway higher than that is included in the flight tests -the so-called high-altitude auto-land approval.
Note from JAR-AWO subpart 1:
The information on characteristics of aerodromes is contained in ICAO Annex 14. Examination of a number of airports used for automatic landing has shows that the following features may be encountered:
Case A.  Sloping runway - slopes of 0.8%
Case B.  Hilltop runway - 12.5 % slope up to a point 60m prior to the threshold ; or
Case C.  Sea wall -6m (20ft ) step up to threshold elevation at a point 60m prior to the threshold.
Figures 4.3

4.4 CATEGORY II/III CERTIFICATION
This section describes the specific requirements for CAT II and CAT III airworthiness certification. It is assumed that the aircraft has a basic airworthiness approval for IFR operations.
4.4.1 REQUIREMENTS
Subpart 2 of JAR-AWO contains the supplementary airworthiness requirements forCAT II operations i.e. to perform ILS precision approaches with decision heights below 60 m (200 ft) down to 30 m (100 ft).
Subpart 3 of JAR-AWO contains the supplementary airworthiness requirements for CAT III operations i.e. to perform ILS precision approaches with decision heights below 30 m (100 ft) or no decision height. Subpart 3 provides a further division of the criteria into:
. decision heights below 15m (50 ft) and
. no decision height.

The latter two cases require the landing system installed in the aircraft to be fail operational ; if the ground roll control is not fail-operational, a minimum Runway Visual Range (RVR) is necessary, a typical value for Airbus aircraft is 75m (JAA).
All values of aircraft airworthiness certification have to be considered as limits, the operational approval may introduce margins to ensure operational safety for every specific case, e.g. operation to a specific airport.
4.4.2 RATE OF MISSED APPROACH
The rate of missed approach or go-around rate below 150m (500ft) may not exceed a prescribed limit of 5% due to performance deficiencies or reliability of the airborne equipment (see JAR-AWO 202 for CAT II and 302 for CAT III).
The go-around rate is demonstrated by simulation.
Definition of a successful approach can be found in JAR-AWO Subpart 2. It reads as follows:
An approach is successful if:
a) The approach from 150m is completed without a system failure.
b)  Between 150m and the start of flare, the speed is maintained within ±5 knots of the approach speed (disregarding rapid airspeed fluctuations associated with turbulence) under all intended flight conditions ;
　
中国航空网 www.aero.cn
航空翻译 www.aviation.cn
本文链接地址：getting to grips with CAT II CAT III operations(39)