Aeromedical Forum

It's winter flying season! Some of the best conditions imaginable can be had on a clear crisp winter morning in Minnesota. You ease the throttle forward and suddenly your C172 feels like a P52 Mustang as it takes off in nothing flat. Same with the climb as you plow through that calm solid air. So what could go wrong on a day like this?

Unfortunately, weather that's good for aerodynamics isn't necessarily good for pilots. Of course, I'm talking about cold injury, something I try to touch on every winter for pilots up here in the Northern Midwest. An unwary aviator can easily lose bits and pieces of his anatomy on the tarmac if he's not respectful of the cold. Not all of us have the luxury of a heated hangar.

When we're flying cross-country in winter it usually means doing some preflights on a windy frigid stretch of concrete. That's an ideal set-up for freezing some part of you-frostbite!

The mildest form of frostbite is frostnip, something that almost every one of us has experienced. First, your skin pales or turns red and feels very cold. Keep trying to fix that loose fairing and you feel prickling and numbness in the exposed skin. As you finally get in the cockpit and the heater cranks up, your skin warms and you may feel pain and tingling. Frostnip doesn't permanently damage the skin. It's just a pain in the finger!

If that darn fairing just won't bolt back on and your exposure increases you will progress to "superficial frostbite." That skin that was previously red turns a pale white. As you rewarm, the skin may look mottled, blue or purple. You may notice stinging, burning and swelling. A fluid-filled blister sometimes appears 24 to 36 hours later. With superficial frostbite you could have some permanent tissue damage.

If you stay out on the tarmac even longer, you can progress to severe (deep) frostbite. Here the skin and underlying tissues freeze solid. The exposed finger, toe or nose becomes numb. All sense of cold, pain, or discomfort is lost. The joints don't bend. The muscles don't work. Again, blisters may pop up 24 to 48 hours later. The underlying skin then turns black and hard as tissue dies. You're screwed!

• If you are experiencing anything more severe than frostnip, you should seek medical attention. Of course there are a number of things you can do to protect yourself from getting into that situation. First of all, wear suitable clothing. That seems like a no-brainer, but how often do you go on a winter flight and neglect to pack clothes suitable for walking out of a forced landing?

Risk of frostbite increases dramatically in temperatures below 5 degrees Fahrenheit Wind chills below - 16 degrees Fahrenheit can cause severe frostbite in less than 30 minutes.

A number of things can increase your chances of getting frostbite. Alcohol or drugs, smoking, dehydration, mental or physical exhaustion all lower your resistance to frostbite. Being at high altitude reduces oxygen supply to tissues and allows damage to occur more easily. Keep that in mind on your next flight to the ski slopes.

One final caution: if you begin to experience intense shivering, slurred speech, loss of coordination or drowsiness, get out of the cold fast and seek medical attention. These are signs of hypothermia-a lowering of your body core temperature. If that continues, loss of consciousness, heart arrhythmias and death can follow. Let the mechanic fix that fairing in the morning!

Fly wisely. See you next month.