WINTER
For some it is a wonderland - for
others, it is the cold, black void between fall and spring
by H. Dean Chamberlain
Article reprinted with permission of
FAA Aviation News
Regardless
of your point of view, winter poses some special restrictions on
flight operations if you don't operate in Hawaii, Puerto Rico, or one
of the other warm areas in this world. Because everyone can't-some
don't even want to-live in such areas, now is the time of year for
aircraft owners and operators to start thinking about what must be
done to get their aircraft and themselves ready for winter ops.
THE AIRCRAFT
The first step is to review the aircraft's pilot operating handbook (POH)
or flight manual. Each aircraft's operating manual lists those things
that owners need to be aware of. For example, the type of oil
viscosity and grease is specified for different operating conditions.
The need for a winterization kit may be listed for certain
temperatures. The kit may include the requirement for a baffle to be
installed on the aircraft to keep the oil within a desired temperature
range.
The flip
side of a winterization kit is if you take your winterized aircraft on
a mid-winter Caribbean vacation, you will have to remove the kit
because of the warmer outside air temperatures. You may have to remove
and reinstall the kit to match your operating environment or risk
turning your exhaust valves into "crispy critters."
Along with
the dangers of flying with frost and snow on the aircraft, the manual
may talk about the care and feeding of the aircraft's battery and
electrical system. Recommended cold weather starting techniques need
to be reviewed and practiced. As more than one pilot has learned on a
cold winter morning, weak batteries don't work well in the cold. A
discharged battery or one with a minimal charge may freeze and
self-destruct. If you have a discharged battery, don't use an
automotive battery charger. The higher charge rate of 15 to 20 amps
will warp the battery plates. A rate of three to four amps is better.
The manual
will also list the proper operation and dangers of the aircraft's
airborne heater. The manual will also explain the need for maintaining
the proper tire pressure for those aircraft operated on wheels. If
your aircraft has control cables, you may want to review your manual
or talk to your mechanic about if the cables need to be adjusted for
the colder temperatures they will be exposed to during the winter. The
reason is the cables expand or contract with changing temperatures.
This, then, changes the tension on the cables and how they feel moving
the attached control surfaces. The proper use of skis will be
explained for aircraft equipped with them in a supplement to the
flight manual.
You may
want to have the aircraft washed and waxed before the first snow. Wax
helps protect the aircraft's surfaces from snow and ice.
An
important item for all aircraft is whether or not the aircraft is
approved for operation in icing conditions. This information includes
the correct or recommended use of any installed equipment needed and
approved for flight into known icing conditions. Even the use of the
lowly pitot heat system will be explained. If the aircraft has deicing
boots or heated props, review how to operate them and how to check
them for proper operation during the preflight.
Another
valuable winter resource is the person who maintains your aircraft.
Your FAA certificated mechanic is an excellent source of winter data.
Now, it does pay to ask if he or she has ever lived or worked in cold
country. Someone who has spent his or her whole career in Miami may
not be the most knowledgeable about flight operations in Maine.
The various
aircraft manufacturers are also good winter resources. Manufacturers
are very knowledgeable about how their products operate in all kinds
of conditions. If they were not, they would not be in business very
long. Aircraft service bulletins and other documents detailing winter
operations provide a lot of data on the safe use of the aircraft and
its many subsystems.
One of the
most critical winter review topics is the safe operation and safety
check of the aircraft's heating system. It is important that the
heating system be inspected for proper operation before it's used.
Unless you are flying a turbojet aircraft that uses bleed air from the
engine for heating, you probably have either the old exhaust heater
shroud on the muffler system or one of the fuel-burning,
self-contained heaters. Each has unique risks. If your heater is the
shroud type system and if the exhaust pipe the shroud goes around has
any holes in it, deadly carbon monoxide and other exhaust gases may
enter your cabin area. More than one pilot has died from carbon
monoxide related incapacitation. Many more have been able to recognize
their own deterioration and shut off the cabin heater, open a window,
and land safely.
Although a
muffler shroud heating system poses special risks, self-contained,
fuel-fired heaters have risks just as deadly as CO poisoning. If the
unit is not properly maintained, there is the risk of an onboard fire
since the unit functions like a mini furnace. In addition to the
possibility of a fire, there is the fact the units burn aircraft fuel.
Pilots need to consider the fuel consumption of the units when
operating at max range. Although the fuel consumption may be
miniscule, it should be considered as part of your normal flight
planning.
Regardless
of the type of heating system aboard your aircraft, the key to its
safe operation is your knowledge of how it functions and ensuring it
is safe to operate.
An
interesting preflight item that can be very difficult to check is
water in the fuel system. Although water in a fuel line can freeze at
altitude and block fuel flow, a more insidious problem is water
freezing in a fuel tank. Think of the amount of water possible in your
tank. In the winter, you now have a large ice cube in your tank. Since
it is frozen solid, any fuel in the tank will check clear of water.
Then when you fly into an area above freezing, your flying ice cube
melts, and you have water in your fuel. Engines don't like water. They
don't run too well on H2O, either. So, if your aircraft has
been out in the weather, check it carefully, and let's keep any
airborne ice cubes confined to your drink at 31,000 feet in the back
of airline XYZ.
Ice can
also lock or jam your flight controls. If the aircraft has been
exposed to ice or snow, make sure the flight controls have not frozen
or been jammed. The same applies if you de-ice your aircraft or move
the aircraft in or out of a warm hanger if the aircraft has been
covered with snow, ice, or frost. Be aware of the danger any time you
have a chance of liquid water and a below freezing aircraft coming
into contact.
THE PILOT
The proper care and feeding of your
aircraft is important. No one argues with the role the aircraft plays
in flight. However, the aircraft, being a machine, is fairly
predictable. Put the right stuff in it, make the proper adjustments,
and it will fly. The same is not true of the pilot. The problem is the
pilot. Bad decision making and failure to properly control the
aircraft are important risk factors for aircraft.
More than
one accident has been caused by pilots who have run their aircraft off
a snow-covered runway or hit a snow bank or flew into a snowy whiteout
and lost control. The need for good weather briefs during the winter
season is very important to help pilots avoid making bad weather
related decisions.
A quick
scan of the National Transportation Safety Board's (NTSB) Internet web
site provided the following comments taken from NTSB accident/incident
reports. The comments are only intended to point out some of the
unique dangers winter poses for pilots and aircraft. Only select
comments were taken from the complete reports.
ACCIDENT ONE
The instrument-rated commercial pilot
received a weather briefing for a VFR cross-country flight. The
briefer described deteriorating VFR conditions along the pilot's route
of flight, and the pilot elected not to file an IFR flight plan. The
pilot departed on the flight and encountered dark night conditions in
mountainous terrain near his destination. Lowering cloud ceilings and
blowing snow were reported in the vicinity of the accident site about
the time of the accident. The airplane impacted mountainous terrain
near the top of a ridge about 20 miles from the intended destination.
The NTSB
determined the probable cause of this accident was: continued VFR
flight by the pilot into instrument meteorological conditions (IMC)
and his failure to maintain sufficient altitude and/or clearance from
mountainous terrain. Factors relating to the accident were darkness,
low ceiling, and snow.
ACCIDENT TWO
The pilot was advised that VFR flight
was not recommended. He contacted Norfolk Approach Control and
requested permission to transition through their airspace. He
indicated that he intended to fly south along the coast in an attempt
to avoid the approaching winter storm. The airplane disappeared from
radar/radio contact while over the Chesapeake Bay.
The pilot
did not possess an instrument rating. It was a dark night with snow
and fog. The NTSB determined the probable cause of this accident was
the pilot's improper in-flight planning/decision making by continuing
flight into known adverse weather conditions. Related factors were the
dark night and the winter storm (snow and fog).
ACCIDENT THREE
The Cessna 150 was substantially
damaged during a forced landing, just after takeoff. The pilot also
provided the following: "It is my belief that [the airplane] was
exposed to three weeks of terrible weather, high winds, sleet, blowing
snow, and very cold (sub zero) temperatures. Some of this
precipitation found its way into the fuel tanks vents and blocked
them."
One of the
preflight procedures in the pilot's operating handbook was: "Check
fuel tank vent opening for stoppage."
According
to the pilot, he performed a preflight inspection per the owner's
manual. The fuel quantity was half full. The wing tank drains were
"frozen stuck," and the pilot decided not to force them open. The
pilot drained about six ounces of fuel from the fuel strainer, and
found "no visible contaminants." He also noted that "the fuel vent
next to the pitot tube appeared to be open."
This
accident is a reminder that during winter operations, pilots must pay
very close attention to all of the aircraft's various vents and
openings because freezing temperatures can cause any water or moisture
in them to freeze and either close the vent or restrict its opening.
So it is important that fuel vents, pitot tubes, static vents, and
engine air sources, to name a few, are open and usable. Ice or mud can
close them if you are not careful.
WEATHER AND YOU
These examples show the importance of
a good weather briefing, and, if you are not instrument rated, of
remaining VFR in VFR conditions and the need for a good preflight.
One of the
facts of winter life is the lack of daylight. Cold, long, dark nights,
and the possibility of blowing snow or the dreaded whiteouts are all
good reasons to be qualified and current for the intended flight. Add
in the risk of cold and hypothermia to anyone forced down in the snow
and you can begin to see the many dangers winter poses for the
unprepared. That includes landing safely at a remote airfield and
finding the FBO closed and the fuel pumps locked and no one within
miles to help you. So you don't have to have an accident to be cold
and miserable, you can find yourself in that situation after a safe
flight-if you have not done your homework and a little prior planning.
THE KEY FOR A SAFE WINTER SEASON
The key to having a safe and
enjoyable winter is to fly within the operating limitations of your
aircraft and your own ability and ratings. Then you need to watch out
for winter weather. Winter can provide some of the best flying
available, but it can also be very unforgiving to anyone who takes it
for granted.
To add to
your winter safety, you need to remember to always file a flight plan.
If it is a VFR flight plan, please remember to close it when you are
safely on the ground. You don't want to close it before you land only
to have an accident within sight of the runway and no one knows you
have crashed. It has happened. In a recent case, the pilot was not
missed until the next day although he crashed near the runway.
Be safe and have a great winter of flying.
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