Winter Flying Tips from Bill Stinson, Beacon Aviation Risk Manager
Winter is in full swing and although some areas are getting an occasional reprieve, 2024 has shown to be a winter with record levels of snow and ice in many areas of the country. Anchorage, Alaska for example has exceeded all records with over 114 inches of the white stuff before February! Frigid double-digit negative temperatures had accompanied the white fluffy stuff.
-25 degrees and a fresh dump of 8 inches of snow welcomed the attendees to the 2024 Alaska Air Carriers Association Conference last week.
So, how does all this affect our aircraft, personnel, and flying opportunities?
Snow is Heavy
A rule of thumb regarding the weight of light, fluffy snow: One inch of snow weighs 0.26 pounds per square foot. That means for every 6.5 inches of snowfall you’ve got the weight of a compact SUV on your roof – or airplane if it is a large twin tied down outside. If the snow is heavy and wet like we experience in Alaska, the rule of thumb is that one inch of snow weighs 1.66 pounds per square foot. Even for small single engine aircraft with the typical 30-foot or so wingspan – this creates a tremendous amount of negative force on the wing structure that is designed to handle positive lift forces.
It is not uncommon for aircraft to suffer structural damage to spars and struts when snow is left to accumulate on aircraft. If you don’t have the benefit of a nice warm hangar for your airplane – the only solution is to remove the snow after every significant snowfall.
Using fabric wing covers helps to keep ice from the wing surfaces and makes preflight easier, but the snow must still routinely be removed following fresh deposits.
Engines Do Not Like The COLD
The propeller acts as a very efficient heat sink which draws the cold deep into the engine core due to it being mounted to the crankshaft. Starting a cold-soaked engine can lead to premature engine wear and even parts breakage. When the outside air temperature drops below 32 degrees, it is a good idea to preheat your engine. If the temperature goes below 20 degrees, it is a must. The best way is to put your aircraft inside a heated hangar and allow it to warm up overnight. But that isn’t always possible.
There are several options of preheating an aircraft engine store in the elements. Electric preheaters are common and can be allowed to work for hours or overnight. But they require an energy source. Propane or gasoline powered force air preheaters are available that blow warm air into the engine ducts, inlets and under the cowling – but they do bring the risk of fire with them.
ICE
Ice accumulation on wings and control surfaces – even a small amount – impedes lift. It also adds weight to the entire surface of the aircraft. If you don’t use covers to keep the ice off, it must be removed physically. Again, rolling a frozen airplane into a heated hangar until it melts off is the best way – but brushing it off is an option. Use a soft bristle brush and be careful of sensitive areas of the aircraft such as antennae, pitot tubes, static ports, trim tabs, and control surfaces. In some cases, chemical de-icing with a glycol solution such as used on airliners is most efficient. However, such facilities and equipment are rarely available to the general aviation pilot or aircraft and comes with a significant cost.
Be aware of the effects of ice on crew and passengers. Winter walking slips and falls are the number one cause of injuries in the winter. Sanding and using snow melt on the ramp is important. The use of proper footwear and ice grippers are suggested prior to entering the airplane.
SURVIVAL GEAR
Forced landings and unplanned stops or stays are always a possibility – but bring added challenges in winter conditions. Adequate survival gear should be available for each occupant. A good rule of thumb is one sleeping bag for each person. Water, shelter materials, fire starting supplies, first aid equipment and emergency rations should be carried in the aircraft. Most important is emergency communication and signaling devices. Those should be carried on the person. You are only guaranteed to have or have access to what is physically on your person when you exit the aircraft in an emergency. Everything else you carry in the aircraft is essentially baggage and you may not be able to access it following egress.
Satellite communicators such as InReach devices use the Iridium satellite network and work anywhere on the globe. An SOS function activation will be answered by the Emergency Rescue Coordination Center. Two-way messaging is possible, and the device is accurate for determining position within 16 feet. In my opinion, that is the best way to ensure someone knows about your situation – will send help – and they will be able to easily find you.
ENJOY THE WINTER WONDERLAND
The cold air and typical low humidity make for excellent aircraft performance. Clear skies and low-angle lighting can make for some beautiful flights and views of scenery. Take a camera along to record your adventures, have fun – but think ahead and be aware of your surroundings and conditions in the air and on the ground this winter.
