A primary objective of the FAA's ATM functions is to provide fair and equitable access to the National Air Space. Traditionally, the FAA has interpreted fairness as prioritizing flights on a "first-come, first-served" basis. The allocation procedures introduced under Collaborative Decision Making (CDM), however, represent a departure from this paradigm: allocations are based on carriers' original flight schedules. Yet in spite of these changes, the concept of fairness under CDM is largely left implicit in the procedures. Different and even conflicting concepts are sometimes used to describe these procedures. Moreover, the achievement of equitable allocations is often complicated by practical considerations. This paper describes a general framework for equitable allocation procedures within the context of ATM, and illustrates its use in reducing certain systematic biases that exist under current procedures. We also discuss other applications of this approach, and summarize practical considerations and implementation issues.