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

Chapter 4
OFFSET MLS
4.1 USE OF MLS CAT I WITH OFFSET AZIMUTH ALIGNMENT
4.1.1 In certain cases it may not be physically practicable to align the azimuth with the runway centre line because
of siting problems, or because airfield construction work demands a temporary offset location. An offset azimuth shall
not be established as a noise abatement measure.
4.1.2 The zero-degree azimuth shall intersect the runway extended centre line:
a) at an angle not exceeding 5°; and
b) at a point where the nominal glide path (elevation angle) reaches a height of at least 55 m (180 ft) above
threshold. This is called intercept height.
4.1.3 The procedure shall be annotated: “azimuth offset ... degrees” (tenth of degrees). The general arrangement is
shown in Figure II-1-4-1.
The provisions contained in Chapter 3 apply except that:
4.2 OBSTACLE CLEARANCE CRITERIA
a) all the obstacle clearance surfaces and calculations are based on a fictitious runway aligned with the azimuth
specified for the final approach track. This fictitious runway has the same length, the same threshold elevation,
and the same distance threshold to intercept point as the real one. The azimuth sector width and the MLS
approach reference datum height are based on the threshold of the fictitious runway; and
b) the OCA/H for this procedure shall be at least: intercept altitude/height + 20 m (66 ft).
II-1-4-1 23/11/06