VFR Winter Flying, Starting Up

Flying during the winter season can be one of the most spectacular experiences there is. Especially in the mountains. But winter time means that we have to take special preparations to safeguard ourselves and the aircraft, so that flying remains fun even in the cold season and does not become a life threatening situation.

Taxiing and taking off from icy or snowy run and taxiways can be difficult. Even in flight a number of situations like carburetor ice or precipitation can make live tempting. On this page we address some of these situations.

Engine starting

With some engines it is recommended to pull the propeller through several times with the ignition off. This will relieve any stress due to oil thickening in the engine and make starting much easier. Only recommended when the aircraft flight manual recommends it (Rotax 9 series for example), this procedure also pre-oils the engine.

Preheating

Engine preheating eases starting by raising the temperature of the engine and oil and reduces warm up time and saving fuel. It can be done in several ways:

• Electric heatings pads attached to the engine sump, this will add to the weight of the aircraft (you could also hang a 100 watt light bulb underneath the sump, this lamp emits lots of heat too).
• An electric heater with hoses running to the engine compartment and the cabin.
• The use of a heated hanger, could be more expensive in increased rental fees.
• Remove the warm oil after the last flight and keep it inside a warm hanger. Add before the first flight of the next day, usually done in very cold places like Alaska, Siberia and northern Canada.

Sometimes the battery is preheated as well with a special harness wrapped around the battery and connected to a suitable electrical outlet. With water cooled engines the use of thermostats in coolant and oil systems may help to keep the engine running at the correct temperatures and warm-up quicker after a cold start.

A winterization kit installed on the air cooled engine will help keeping the cylinder head and oil temperature within limits set by the manufacturer during flight.

Difficult starts

Starting an engine can be difficult when temperatures are dropping, it will require more priming (carburetor engines in particular) and therefore increase the change of fire during engine start. Those engines lucky to be equipped with fuel injection and a FADEC should start a whole lot easier when temperatures are low.

Diesel engine operators should expect to have to glow somewhat longer before starting the engine. FADEC equipped diesels regulate this automatically. Diesel fuel should be prepared for colder temperatures (winter diesel), if not, refuel with JET if you expect to fly at higher (colder) altitudes.

Taxi & Take Off

In the winter special problems arise like trying to taxi on frozen, ice of snowy surfaces with almost or no braking action available, steering could be a problem too (certainly for a taildragger). It is important to try to remain out of pot holes, heavy snow patches, slush and the like. Wheel pants fill up easily with with show adding to the weight and possibly freezing the brakes solid.

Snow increases the takeoff and landing distances by some 25%. Read in Aircraft Take Off & Landing Performance about it.

Fog can be a problem too. Early morning departures with freezing fog (common with airports not close to the sea) and running propellers can create ice build up on the propeller tips and resulting in heavy unbalance. You will just have to wait it out until the fog lifts.

Remove frost

At any indication of frost on the aircraft, check the wings and clean them. Do not try to takeoff. The aerodynamic properties of the wing are altered by frost and the stall speed is increased due to the added weight. Snow or ice on the wing reduce lift and the aircraft is increased. Frost can sometimes hardly be seen but the result is that the airfoil is changed and with that, the flying capabilities of the aircraft.

With propeller aircraft the left turning tendencies (with engines that rotate clockwise) are more pronounced due to slippery surfaces, be prepared and advance the throttle more slowly than you are used too.