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Airports use a variety of methods to maintain the surface friction, and therefore the breaking action and directional control on runways if they are contaminated by snow and/or ice.
The majority of airports use mechanical methods to clear snow and ice but, depending on climatic conditions, may also apply sand or de-icing chemicals in solid (salts) or liquid form. The purpose of these products, often referred to as Pavement De-icing Products (PDP) or Runway De-icing Fluids (RDF), is to reduce the freezing point of the contaminant to cause it to melt.
Types of Pavement De-icing Product
The products most commonly used by airports are:
- Ethylene/Propylene Glycol-based fluids
- Sodium Acetate
- Potassium Acetate
- Sodium Formate
Environmental and Corrosion Issues
Chemicals used to de-ice runways can pose an environmental hazard and, as a consequence, urea and glycol-based de-icing products have generally been replaced by alkali-metal-salt-based products (KAc and KF). However, the use of these products may be linked to failures of carbon brakes and corrosion of Cadmium plated airframe components.
Interaction Between Pavement and Aircraft De-icing Products
When runway de-cing products (KAc or KF) splash onto control surfaces during taxi or take-off run, they may affect the performance of any applied aircraft de-icing product. The effects may include a reduction in Holdover Time or, in thickened fluids (Type II and IV), may accelerate the precipitation and build up of thickener residues encouraging greater moisture update on the rehydration of those residues, which may cause handling problems in flight.
- Transportation Research Board (USA) - "Impact of Airport Pavement Deicing Products on Aircraft and Airfield Infrastructure"
- EASA Safety Information Bulletin (SIB) 2010-26 Potential Performance Degradation of Anti-icing Fluids - Reduced Holdover Times