2.2.6.1 The manoeuvring zone of the landing area
extends the area in which a helicopter may manoeuvre with safety by
enlarging, to a diameter of at least 1.3D, the area over which the
rotors of the helicopter may overhang without danger from high obstructions.
When the landing area is at the ship's side, safe helicopter access
will be enhanced by widening, where possible, the boundaries of the
obstruction-free manoeuvring zone at the ship's side to a dimension
of at least 2D (see
figure
1).
2.2.6.2 If it is impossible to remove all obstructions
from the manoeuvring zone, a graduated increase in the permitted height
of obstructions, from 0.25 m at the circumference of the clear zone
to a maximum of 1.25 m at the circumference of the manoeuvring zone,
is acceptable. However, such height above 0.25 m should not exceed
a ratio of one to two in relation to the horizontal distance of the
obstruction from the edge of the clear zone (see
figure 3). So, for example, an obstruction
of 1 m in height (0.75 m more than the maximum obstruction height
in the clear zone) should be at least 1.5 m outside the circumference
of the clear zone. All obstructions in the manoeuvring zone should
be clearly marked in contrasting colours.
2.2.6.3 To assist the helicopter pilot in his
positioning, the circumference of the manoeuvring zone should be indicated
by a broken yellow line of 0.2 m width (see
figures 1 and 2).
Figure 3 Landing area - permitted height of obstructions (elevation)