This International Standard identifies and summarizes the various factors that shall be considered and evaluated by the design or specifying engineer in establishing performance requirements for four-wheel-drive aircraft tow tractors. The International Standard provides a summary of design factors that shall be considered in establishing performance requirements, as well as various tabulated design data and explanatory examples. It is not within the scope of this International Standard to specify a comprehensive set of design criteria for aircraft tractors, but only those relating to performance requirements.