Rationale: AMS1426 is a specification for runway deicing fluid in liquid form formulated with a specific class of compounds, namely, glycols. AMS1426 was introduced in 1980 and its latest version AMS1426C was last revised in 1993. In 1995 a new specification for liquid runway deicing fluid was introduced, AMS1435. AMS1435 is a generic performance based specification where the runway deicing fluid can be formulated with any class of compounds that fulfills the specification requirements. When introduced, AMS1435 was meant to replace all runway deicing fluid formulated with specific class of compounds. As of January 2014, AMS1435 is an active specification undergoing regular updates. AMS1435 has replaced AMS1426. AMS1426 is not supported, is obsolete and, therefore, must be cancelled.