13.2.1
Final approach and take-off area
(FATO) is a defined area over which the final phase of the
approach manoeuvre to hover or landing of the helicopter is intended
to be completed and from which the take-off manoeuvre is intended
to be commenced.
13.2.2
Limited obstacle sector (LOS) is
a sector extending outward which is formed by that portion of the
360° arc, excluding the obstacle-free sector, the centre of which
is the reference point from which the obstacle-free sector is determined.
Obstacles within the limited obstacle sector are limited to specified
heights.
13.2.3
Obstacle is any object, or
part thereof, that is located on an area intended for the movement
of a helicopter on a helideck or that extends above a defined surface
intended to protect a helicopter in flight.
13.2.4
Obstacle-free sector is a
complex surface originating at, and extending from, a reference point
on the edge of the FATO of a helideck, comprised of two components,
one above and one below the helideck for the purpose of flight safety
within which only specified obstacles are permitted.
13.2.5
Touchdown and lift-off area (TLOF) is
a dynamic load-bearing area on which a helicopter may touch down or
lift off. For a helideck it is presumed that the FATO and the TLOF
will be coincidental.