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threat when fixing your position by a
single light source. When little or no
light is on the surface and a
prominent one comes into view, it
may seem that the light is above the
232 Operational Flying
horizon, which could lead you to
pitch into a steep attitude in keeping
with the resulting false horizon.
Sometimes the effect is not much
more than an uncomfortable
climbing sensation even when you're
straight and level, but an obscured
windscreen could make objects
appear lower than they really are.
This will be more apparent with high
intensity runway lighting, which may
also give you the same effect that
actors have on stage, where they
can't see the audience through the
bright lighting. The lack of normal
contrast will also upset your altitude
perception, making you feel further
away and higher than you are. As a
result, on a final approach you could
find yourself too low and fast. The
solution is to use every piece of
sensory information you can,
including landing lights and
instruments (look ahead and slightly
to the side of the light beam).
Problems will arise if several of the
above factors affect you at once,
especially if the landing point is
sloping—this is where frequent
cross-checking of altimeters is
important. The illusions you might
get with sloping ground include:
Problem Illusion Risk
Downslope Too low High approach
Upslope Too high Low approach
Rain Closer Low approach
Narrow Too high Low approach
Wide Too low High approach & flare
Bright lts Too low High approach
The trick with landing is to get to the
point where you think the wheels are
going to touch the ground – then go
down another 30 feet.
Helicopter landing sites must be
checked out in daylight on the same
day as they are to be used at night.
Preflight checks should allow for
night flying—carry a torch, and 2
landing lights are preferred.
Permission to enter the rotor disc is
given by flashing landing lights.
Hovertaxi higher and slower than by
day, making no sideways or
backwards movements. Great care
should be exercised in pointing the
Schermuly flares to a safe place at all
times (which is admittedly a bit
difficult when they're fitted and the
fuelling truck pulls up right alongside
them). The flares should not be
armed at this stage, but at the
holding point immediately before
take-off and disarmed at the same
place after final approach. They
should also be disarmed after
reaching cruising altitude.
The maximum useful height for
discharging a flare is around 1800
feet. Its burn time is 80 seconds,
during which time it will fall about
1500 feet. Therefore, having
established autorotation after an
engine failure at night, the first flare
should be discharged immediately, or
on passing through 1800 feet,
whichever is later. Don't bother
doing it before this, as they will be
useless. Due to the way the switches
work, and depending on the height
at which your engine stops, you may
not be able to set off more than one
flare before landing, but, if possible,
the second should be discharged
between 800-1000 feet agl.
In autorotations at night, use a
constant attitude, at whatever speed
is comfortable, to keep the beam
from the landing light in the same
position on the ground, because
Special Use Of Aircraft 233
otherwise it will shine up into the air
when you flare, from which position
it's no good to you at all.
Winter Operations
Although colder air means there's
less danger of exceeding temperature
limits, there are hazards, too,
including freezing precipitation, low
ceilings and cold temperatures.
Rapid changes in these are typical,
and it’s possible to get weathered in
for days at a time, so don’t forget
your chocolate bars.
The Weather
When it gets to below -20 or so,
contact gloves will prevent your skin
freezing when it comes in contact
with cold metal, which is a more
efficient conductor of heat than air
is. You may also need sunglasses.
Always dress properly—in a forced
landing it could be that the clothes
you wear will be the only protection
you have. Also, being cold when you
are actually flying is a Flight Safety
hazard – metal foot pedals will
conduct heat away from your boots
very quickly. Extra time for planning
should always be allowed and the
　
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