The Federal Aviation Administration (FAA) is considering many new technological solutions to improve the efficiency and capacity of the National Airspace System (NAS). Most of these technologies require the addition or modification of equipment not only on the ground, but also in the aircraft that operate in the NAS. If these aircraft equipage costs are too high, the owner/operators may not equip their aircraft and the overall program might not proceed as desired.Presented is a methodology that can be used to define and forecast the range of user responses to new technologies that require aircraft equipage. The responses can be linked to potential FAA actions and policies regarding the technology, which could include: relying solely on voluntary user equipage, supplying subsidies for all or a portion of the avionics cost, and creating rulemaking to require certain capabilities in specific airspace. This user response forecast, when combined with model-or type-specific aircraft knowledge, provides an estimate of the future mix of aircraft capabilities, and can be utilized to determine overall fleet upgrade costs for unequipped aircraft. An example is shown for Automatic Dependent SurveillanceBroadcast (ADS-B) that draws upon previous avionics costing work for the FAA by the same authors published in MTR 05W0000082.