The Operating Environment and Aircraft Performance

ICING

Environmental factors are a constant threat for aircraft and their crew. Many different environmental factors can have a drastic effect and change an ordinary flight in to one you won't forget. I have had firsthand experience with, in my opinion, one of the more serious environmental factors, ice. Aircraft are no strangers to ice, but it's when the ice becomes thick enough and starts to disrupt the fundamental principals that make the aircraft fly that it gets serious. Ice can affect the aircraft in three main ways: weight, lift, and drag. Think of a boat out at sea in the winter, the deckhands are out there with hammers trying to break off the ice, because if they don't the ship could sink. The same thing can happen for an aircraft, too much weight is dangerous. Ice can accumulate on all surfaces of an aircraft, but when it accumulates on the airfoil surfaces this begins to limit the amount of lift the aircraft can generate. Ice effectively changes the shape of the wings, making them less efficient. The third aspect of icing is drag. Aircraft surfaces are meticulously engineered to be as aerodynamic as possible and any unwanted addition to that surface can cause flight control problems and increase your fuel consumption drastically.

There are many effects icing can have on an aircraft. Many of which can be mitigated by simply flying around known icing conditions. However, that's not always possible. Anti-icing systems on aircraft have become very reliable, and work off a very simple ideal, hot air. The aircraft's bleed air system can send hot air to the parts of the aircraft most susceptible to icing, such as the wings and engines. This keeps the surfaces free of any ice accumulation and prevents the problems I spoke of earlier. It's the job of the crew to keep out of known icing areas and know how and when to use the aircrafts anti-icing system to prevent any mishaps. 

Icing which can be very dangerous if not corrected immediately. This is any deposit or coating of ice on an object. Ice can collect on any component of the aircraft to include wings, props, windshields and air intakes. Basically, the ice limits all aspects of performance such as increased drag, increased weight, decreased lift and reduced thrust. A couple mitigating methods include anti-freeze fluids and heating devices. These can be used to remove ice and prevent it from collecting. When neither of the mitigating methods work then avoidance is the only option. "When ice formation is observed in flight, there is only one certain method of avoiding its hazards and that is to get out of the ice-forming layer as quickly as possible." (weather.gov)

References:

Icing Hazards (weather.gov)