Global Aviator December/January 2017/18 / Vol. 9 / No. 12 47
or the wind direction, or all of the
above. Every single confined area is
different and must be assessed and
approached in a different manner.
So what are the possible difficulties?
The first one, of course, is that you might
fly into something or try to land on an
unsuitable surface. This might sound
unlikely, but obstacles are very difficult
to see from the air. Steeply sloping
ground can look flat, and fields sewn
with crops can appear like meadows. As
mentioned previously, wires represent a
major hazard. I was taught that the first
thing you must do before a confined
area approach is ascertain exactly where
the wires are - since there are sure to be
some, somewhere! It was good advice.
The next potential problem is
that of needing to take off and land
vertically or nearly so. Yes, helicopters
can do this. But it isn’t particularly
easy, and it isn’t recommended. Firstly,
in the admittedly unlikely event of
an engine failure, it would be very
difficult to land safely. A helicopter
autorotation, in which you descend,
then flare and raise the collective to
cushion your landing, needs airspeed.
For this reason helicopter pilots are
generally taught to stay out of the ‘avoid
curve’ - the area in which surviving an
engine failure would be difficult, if not
impossible. However, if your choice
is between being in the avoid curve
or being in the trees...well, there’s no
contest really. But it isn’t something
you contemplate or undertake lightly.
The next difficulty is that landing
vertically requires great care. You cannot
just lower the collective, descend at
any rate you feel like, and dump thehelicopter on to the ground. Most
people will have noticed that helicopters
usually descend very slowly, and
there is a reason for this. If a helicopter
comes down vertically, it can get into
a condition known as ‘vortex ring’,
in which it descends into its own
downwash, gets out of control, and
crashes. This is not a common problem,
as in order to get into vortex ring you
need to be in a descent, with almost
no airspeed and with power applied.
This is fairly unlikely to happen with
a normal approach and landing if it
is done properly. However, if you are
coming straight down in a confined
area, all these three conditions are likely
to be present. There are generally clear
signs of incipient vortex ring – the
helicopter starts to shudder and shake,
and becomes difficult to control. So