Particularly during winter months, de-icing and anti-icing equipment are vital to proper aircraft operation. However, temperatures at higher altitudes drop significantly regardless of the season, so there is reason to exercise caution year-round. The type of equipment used depends on the particular aircraft in question, but as a general rule, turbine aircraft are better prepared for icing conditions than jets. The presence of ice on the outside of an aircraft can pose a danger to the vehicle, as ice causes it to be prone to a loss of lift and stalls while moving at faster airspeeds. Anti-icing is preventative, keeping the ice from forming in the first place. De-icing equipment, on the other hand, removes ice that is already accumulated on the outside of the aircraft. The majority of piston aircraft feature one of these two systems, while turbine aircraft often feature anti-icing and de-icing equipment.