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Winter Cometh - Keeping Warm On A Cold Winter Day

Reprinted with permission from FAA Aviation News

As I noted in the Editor's Runway on the inside back cover of this issue, editorially, summer is gone and winter cometh. What this means for many pilots and aircraft owners in the Snow Belt is a long, dark, cold period before spring flying starts again. In some cases, this is because of the type of aircraft involved. In other cases, it is because of the general inconvenience of flying in the cold and snow. Snow and frost removal takes all the fun out of pre-flighting an aircraft on a cold January day. Now if you live in Florida, Arizona, or Hawaii, you may not understand what it is like to preflight in the cold, but please read on.

I spoke with a pilot of a weight-shift trike aircraft at the Sun'n Fun Flyin last April in Florida. Although it was T- shirt and shorts weather on the g round at the time, he told of flying down the coast of Florida at about 3,000 feet while wearing an insulated snowmobile outfit. He said he was comfortable at altitude, but he was sweating because of the heat when he had to land to refuel.

For those intrepid aviators who fly open or open cockpit type aircraft such as this trike pilot or some of the ultra light or light sport aircraft during the winter, they have to not only ensure their aircraft are prepared for the cold, but they themselves must also be prepared. Without proper clothing and facial protection, they risk not only hypothermia, but also frostbite on any exposed skin.

In the case of enclosed cockpit aircraft with airborne heating systems, their pilots may be more comfortable in flight, but they face another type of danger unique to aircraft with certain types of heaters. That is the risk that their heaters may be leaking carbon monoxide (CO) gas into the cockpit. Carbon monoxide is a deadly gas because it effectively prevents the blood from absorbing oxygen vital to life. As noted in the FAA's Pilot's Handbook of Aeronautical Knowledge, FAA - H -8083-25, on page 15-2, under the general chapter title, Environmental and Health Factors Affecting Pilot Performance, the handbook describes the various types of hypoxia that pilots need to be aware of. Under the subheading of Hypemic Hypoxia, it states one of the types of hypemic hypoxia is when, '...hemoglobin, the actual blood molecule that transports oxygen, is chemically unable to bind oxygen molecules. The most common form of hypemic hypoxia is carbon monoxide poisoning.'

Since many general aviation aircraft use part of the exhaust system to heat the air going into the cockpit, aircraft owners and pilots need to be aware of the fact that a hole or crack in the portion of the exhaust system that the heater shroud surrounds can allow exhaust gas to enter the cockpit along with the heated air. This type of heater is the most common type of heating systems installed in many general aviation aircraft. The other type of heating system used in other general aviation aircraft is basically a small, fuel-fed 'furnace' that heats ram air that is directed into the cockpit. A defective or worn furnace can allow combustion products, which includes CO, to enter the cockpit. In either system, the best defense is a properly inspected and functioning heating system.


To reduce the risk of CO entering the cockpit along with heated air, some pilots buy one or more of the various types of chemical and electronic CO detectors that can be installed in an aircraft to detect dangerous levels of CO. Pilots should review the latest handbooks and manufacturers' guidance for more detailed information on how to recognize and cope with a heating system that is permitting CO to enter the heating system. At a minimum, pilots should, if suspecting a CO leaks in their aircraft, close or shut off the heating system and open any fresh air vent or vents as applicable.

According to the Pilot's Handbook of Aeronautical Knowledge, some of the first symptoms of hypoxia include euphoria and a carefree feeling. With more oxygen starvation, it says '...the extremities become less responsive and flying becomes less coordinated.' Other signs may include cyanosis (blue fingernails and lips), headache, decreased reaction time, impaired judgment, visual impairment, drowsiness, and lightheaded or dizzy sensation, tingling in fingers or toes, and numbness. The handbook noted that although symptoms vary by individual, these symptoms are common. A hidden danger in all of these is the fact that when a pilot needs to be the most aware that a problem is developing, the root cause of the problem may impair the pilot's judgment to the point the pilot may not want or be able to take effective action to correct the problem. Corrective actions for hypoxia include using supplemental oxygen, flying at a lower altitude, shutting off the source of CO, and breathing fresh air when able.


Checking the aircraft's heater system is only one of the checks aircraft owners and pilots should be aware of when preparing an aircraft for winter operations. As I said in the Editor's Runway, the aircraft's flight and maintenance manuals are the best sources of information for preparing your aircraft for winter operations. The same is true of your aircraft 's maintenance personnel. They know their local area's weather conditions and how to service your aircraft.


The real challenge for safe winter flight may be preparing the pilot. In addition to preparing their aircraft and heating system for winter operations, pilots need to review material for their own benefit.

For example, now would be a good time to review your own decision-making criteria. What are your decision-making limitations for winter flights? If your aircraft is not approved for flight into known icing conditions, have you considered under what weather forecast conditions will you launch? What are your divert criteria?

Have you reviewed the FAA's regulations applicable for your proposed flight? Have you reviewed the current Notices to Airmen (NOTAM) for any re ports for your airport of departure and landing? Flying to an airport closed for snow removal can make for a long day.

Do you have the appropriate survival equipment for your route of flight? FAA Aviation News continues to support the well-publicized viewpoint that you should wear what you want to walk home in when going flying during the winter. A year or so ago, there was a well-publicized report of a winter accident out west in the mountains where one of the survivors was wearing shorts. After all, no one planned to walk home in the snow when the flight departed. Certain areas of Canada and the State of Alaska have regulatory requirements for specific types and amounts of survival equipment.

Have you considered the best use of inhabited areas and routes along highways and other populated are as to be near help in case of an accident or precautionary landing off airport? In many cases, a safer route may only add a few extra miles to your flight plan while increasing your odds of rescue significantly.

Do you have a plan to deice or defrost your aircraft in case it gets snow covered or exposed to freezing rain? From fuel tanks to control surfaces to landing gear, have you considered how you would deice your aircraft? If you have a retractable gear aircraft, does your flight manual re commend you leave the gear down a little longer after takeoff to help blow off any potential source of freezing liquid before retracting the gear. There have been cases where wheels have frozen in the 'up' position. Do you have a plan for dealing with slush and freezing rain and snow on your landing gear as you taxi out for takeoff and after landing? What about frost on your wings?

When was the last time you checked your pitot's heating system? What is your plan for starting your aircraft if your battery dies? Do you know how to protect your aircraft's battery when the temperature is below freezing? Do you know how to jumpstart your aircraft? Does it have any special safety precautions for jumpstarting? Considering the risks of hand propping an aircraft with snow or ice on the ground, do you have a plan and a safe method for hand propping your aircraft if you decide to do so?

Do you have a plan for operating on a slippery runway and ramp area? With all of the news stories about the dangers of super-cooled water droplets, have you considered or know how your aircraft might perform with a significant amount of ice attached to it?

Do you know the capabilities of the various types of deicing and anti-icing fluids available? Are they approved for your particular type aircraft? Some fluids have a minimum rotation speed necessary so that the fluid will blow off the aircraft. Is your aircraft 's rotation speed fast enough for the available fluid?


These are only a few of the things a well-prepared aviator or aircraft owner needs to think about when operating in snow country. FAA has published many snow and winter operations advisory circulars as well as other safety recommendations for those operating in snow country. Those living full-time in the Snow Belt should be aware of how to operate safely when the landscape turns white and cold, but everyday new pilots are certificated and new and old pilots from the sun-belt venture into the frozen north. They may not know or remember the safe operating techniques needed to flying in the cold areas and especially during the limited daylight hours we all have during the winter months. For those pilots, we recommend they contact the Flight Standards District Office (FSDO) Safety Program Manager (SPM) in the area they are planning to visit for the latest safety information. The SPM may refer you to one of the office's volunteer aviation safety counselors who may be an expert on winter operations in that area for more advice.

Winter can be a beautiful and safe season for flying as long as you and your aircraft are properly prepared for its unique challenges. The secret is simple. It is the same for any season. With proper planning, preparation, and good risk management, you can have a safe and fun filled winter season. But the single most important safety practice any pilot can do is to file and activate, as appropriate, a flight plan. FAA Aviation News hopes everyone has a safe winter-flight season.

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