Document ID: chunk:federal_register_of_legislation:F2024C01244:reg:5:p74
Version: federal_register_of_legislation:F2024C01244
Segment Type: reg
Provision Reference: reg 5 (pt 74/225)
Character Range: 505869–508769

(i) at the top of the tower;

           (ii) at the point of the tower that is the lowest level of the catenary of the wires or cables;

           (iii) at approximately midway between the 2 levels referred to in subparagraphs (i) and (ii).

Note   In some cases, paragraph (b) may require the bottom and middle lights to be located off the tower on stand-alone supports.

       (12) For subsection (11):

(a) the number and arrangement of lights at each level mentioned in subparagraphs (11) (b) (i), (ii) and (iii) must be such that the object or structure is indicated from every angle of azimuth; and

(b) if a light would be shielded in any direction by an adjacent object or structure, the light so shielded may be omitted, provided that such additional lights are used as are necessary to retain the general definition of the object or structure.

     Figure 9.31 (1)-1   Typical lighting of tall hazardous obstacles (illustrates matters)

     Figure 9.31 (1)-2   Typical lighting of a group of hazardous obstacles (illustrates matters)

     Figure 9.31 (1)-3   Typical lighting of horizontally-extended hazardous obstacles (illustrates matters)

     Figure 9.31 (1)-4   Typical lighting of towers and large hazardous obstacles (illustrates matters)

9.32 Characteristics of low-intensity obstacle lights

       (1) Low-intensity obstacle lights must have the following:

(a) fixed lights showing red;

(b) a horizontal beam spread that results in 360-degree coverage around the obstacle;

(c) a minimum intensity of 100 candela (cd);

(d) a vertical beam spread (to 50% of peak intensity) of 10 degrees;

(e) a vertical distribution with 50 cd minimum at +6 degrees and +10 degrees above the horizontal;

(f) not less than 10 cd at all elevation angles between –3 degrees and +90 degrees above the horizontal.

Note   The intensity requirement in paragraph (c) may be met using a double-bodied light fitting. CASA recommends that double-bodied light fittings, if used, should be orientated so that they show the maximum illuminated surface towards the predominant, or more critical, direction of aircraft approach.

       (2) To indicate the following:

(a) taxiway obstacles;

(b) unserviceable areas of the movement area;

        low-intensity obstacle lights must have a peak intensity of at least 10 cd.

9.33 Characteristics of medium-intensity obstacle lights

       (1) Medium-intensity obstacle lights must:

(a) be visible in all directions in azimuth; and

(b) if flashing — have a flash frequency of between 20 and 60 flashes per minute.

       (2) The peak effective intensity of medium-intensity obstacle lights must be 2 000  25% cd with a vertical distribution as follows:

(a) for vertical beam spread — a minimum of 3 degrees;

(b) at -1 degree elevation — a minimum of 50% of the lower tolerance value of the peak intensity;

(c) at 0 degrees elevation — a