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RCP1209_012-015_Feature 12/31/09 7:17 AM Page 13
By Commander Dan Bitton –
Winthrop Harbor Police Department
Law Enforcement Aviation Coalition
Eurocopter EC-135T2 - HB-ZEF
Air Zermatt AG
Photo: Julien Ritz - www.helidropzone.ch
For those law enforcement agencies
that operate in cold weather environ-
ments, winter adds dangers we must con-
sider before launching.
Winter brings a combination of high
moisture content and cold temperatures
that pose a threat of engine, airframe, and
blade icing. During day and night opera-
tions, snow and ice become significant
threats in many ways. Ice on a ramp or
ice or snow on a helipad during a rapid
spool-up or rapid spool down can cause
the helicopter to yaw. Snow can lead to a
whiteout during takeoff and landing. Dur-
ing night NVG operations, a gradual in-
crease in snowfall can lead to loss of
situation awareness and CFIT, or to in-
stant IIMC conditions that can result in
loss of control.
An awareness of these conditions along
with proper training, mission planning
and crew-coordination can prevent flight
crews from getting caught in these traps
and thereby prevent accidents. The bad
news is that accidents involving loss of
situational awareness and the resultant
loss of control and CFIT are usually fatal
accidents. The good news is that these ac-
cidents are typically avoidable.
At the risk of boring you with physics,
the basics a pilot and all crewmembers
should know about icing begins with the
fact that icing can occur in conditions of
high humidity when the ambient temper-
ature is at or below 0 degrees C. Note that
this does not require you to be in the
clouds. Icing can also occur at higher
temperatures during times of falling baro-
metric pressure, so for safety sake let’s
just say that with temperatures at or be-
low 5 degrees C, high humidity, tempera-
ture and dew point being nearly even, we
must be aware of the dangers of ice ac-
cumulation.
The primary effect of ice on a heli-
copter’s blades is drag and loss of lift.
During temperatures between 0 and -3C,
ice will form on the leading edge from the
Continued on page 14
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