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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 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 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.

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.

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).

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.

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 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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