Cold Weather Operations 2007-01-11

Winter—it’s cold, it’s dark and sometimes it seems like spring will never come. But, lots of pilots live in cold country, and there’s no sense letting our airplanes sit idle all winter. Although it takes more effort and better preparation, winter flying can indeed be tolerable and sometimes even downright fun. So, if you’re up for the challenge, let’s consider some things you can do to mitigate the effects of winter and enjoy some flying.

A heated hangar is hands down the best gift you can give yourself and your airplane. It allows you to preflight in comfort under good lighting. Outdoor pre-flights at minus-20 degrees F can be more “concise” than might be preferable. A hangar prevents ice or snow accumulation between flights, and the slush that accumulates on the airplane’s floorboards can evaporate in a warm hangar.

An unheated hangar isn’t quite as nice as a heated one, but it still has advantages over parking outside. You won’t need to apply wing, windshield and tail covers, or secure the controls and attach tiedowns every time you park. It’s still important, however, to carry a full set of covers in case you have to park outdoors en route because of a weather delay. You should always be prepared to land and wait out weather, and having the proper equipment on board makes the decision to land at a strange airport easier.

An insulated engine cover is essential. If you park outdoors during a stop for lunch or weather, an insulated cover will keep the engine warm enough to restart, even at temperatures well below zero. An engine cover also helps with preheating. If the airplane lives outdoors or in a cold hangar, it needs an engine preheat system. In really cold country a full electric preheat system, such as those manufactured by Reiff or Tanis, is your best choice. Combined with an insulated engine cover, these heaters will ensure that your engine is thoroughly warm when you’re ready to fly. In milder temperatures, a less complex heating system may suffice.

If your tiedown has no electricity, a blast heater such as the Red Dragon, or a generator to operate your electric heater are other options. Blast heaters warm the engine quickly, so while the cylinders may be warm, the engine’s core may still be cold. Give the heat time to normalize throughout the engine by allowing plenty of time for it to thoroughly preheat before a flight. Most engine manufacturers suggest that you preheat when temperatures reach around 10 degrees F. Personally, if it’s at or below the freezing point, I always preheat.

If you didn’t get your wing and tail covers on quite soon enough and your plane is covered with snow or ice, what do you do? If it’s heavy ice, move the aircraft into a heated hangar, let it melt and dry completely. If it’s loose snow that hasn’t thawed and refrozen, a push broom with soft bristles will remove most of the contamination.

How much snow or ice is acceptable for flight? In reality, for total safety, none. But that’s a decision each pilot has to make for him or herself. At the very least, the safest bet is to remove all contamination from the flying surfaces. By using a broom or rope, you may be able to polish simple frost on the wings to a surface smooth enough for safe flight.

Another option for deicing is to keep a small garden sprayer at home with a half-gallon of RV antifreeze in it. Before you head to the airport, top off the sprayer with hot tap water and spray the entire plane with this deicing fluid mixture.

Engine oil is a subject of much debate. I like multigrade oils. If you prefer straight-weight oils, be certain to change to a slightly lower viscosity in the fall, when temperatures start dropping. It’s always safest to use the grades of oil recommended by the engine’s manufacturer.

Engine manufacturers suggest that you get your engine’s oil temperature to at least 180 degrees for 20 minutes any time you fly. This will allow the heat to eliminate any moisture in the oil. There may be nothing wrong with using duct tape to cover half your oil cooler in cold weather, but a better approach is to install the manufacturer’s recommended winterization kit. If your aircraft has no approved winterization kit, ask your mechanic for the safest way to get the airplane’s oil temperatures into the recommended range.

Make absolutely certain that your engine oil breather line has a “whistle slot” or supplemental breather hole, somewhere high inside the cowling. Your oil breather line opening will freeze over in cold weather. A supplemental breather hole will prevent pressurization of the engine case from pushing the nose seal out of your engine, and loss of engine oil.

Okay, the airplane is ready, but how about the pilot? Flying in winter offers some of the best flying weather of the year: no thunderstorms, generally good visibility and more. Yet it can also leave you in the dark and cold. Each pilot who flies in winter should have a good warm coat, boots, hat and gloves in the plane or better yet, on their person. Good-quality, winter-weight long underwear is a necessity in very cold country.

I consider a survival kit to be essential in the winter, plus a good winter sleeping bag and insulated sleeping pad for each occupant. I also carry a minimal selection of survival items on my person, in the event I have to depart the plane in a hurry. If you “arrive” somewhere off airport it may take a while for help to come. I consider a good knife, fire starters, a signal mirror and some parachute cord to be an absolute minimum kit to carry on one’s person.

One of the new 406 mHz personal locator beacons (PLB) is a great addition to your personal survival gear, though they’re a bit expensive and bulky. My Alaskan friend Ray Tremblay used to say, “Survival gear is whatever you have in your pockets when you go out the door. That bag of stuff in the back of the airplane is camping gear, not survival gear.” Don’t forget the cell phone—it could save the day.

The pilot should be current in the airplane, for both day and night. Winter days are short, and a minor weather divert can push your landing into darkness. You did check the aircraft’s lights (including panel lights) prior to takeoff, right?

Utilize all the weather information you can find. My ideal weather briefing is done in front of an Internet-connected computer, on the phone with an AFSS briefer. It’s easy to miss subtle points in a weather briefing, so having a second opinion can be invaluable. Local NOTAMs can be critical to safety, and there’s only one source for local NOTAM information: the Automated Flight Service Station.

For a more experienced pilot, flying on and off ice can be done safely, albeit with extreme caution. If there were any crosswind, I wouldn’t fly from glare ice. With a wind straight down the runway, or no wind, flying with minimal braking action can be done safely, but it’s still not a good idea. Being conservative about distances required to land and stop, and being able to land the airplane precisely where you want to land it, every time, is essential. If you get sloppy when it’s icy, you’re in for some pain.

In some conditions, you can’t even stand up on the ramp because of ice. In such a case, it might be a great day to find a warm fire and a good book, and read about aviation. Remember, flying is as much a thinking game as it is a set of physical skills, so keep your mind engaged in aviation as well.

So, how do we knock some of the rust off during these long winter months and keep our airplane operational?

If you’re operating a tailwheel airplane, consider installing skis. Ski flying is more fun than you can stand—really! You’ll have more freedom and more challenges. Straight skis are limiting at many airports, since management removes snow and ice from taxiways and runways. However, penetration or retractable skis offer the flexibility to operate from bare pavement as well as snow-covered terrain.

If your plane isn’t a taildragger, or you simply aren’t into airport operations, look for short day-trips close to home base. Upon arrival at your “target,” fly a couple of patterns with landings. Back at your home airport, fly a few more patterns. This is especially valuable at night, when most of us don’t get enough practice.

I may not have convinced you to fly twice a week this winter, but with just a bit of preparation, you’ll find that winter flying on nice days can be really enjoyable and rewarding.

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