Concerns Exist About Whether WAAS Can Satisfy Performance Requirements Within Budget and on Schedule

While system developers and outside experts have confidence that WAAS can achieve most key performance requirements within current cost and schedule estimates, four concerns are worth noting: (1) the ability of WAAS to provide the level of service for precision approaches provided by existing ground-based systems; (2) the ability of computers to process the large quantities of GPS/WAAS data within a few seconds; (3) the vulnerability of GPS/WAAS signals to interference; and (4) the need for additional satellites to achieve the availability requirement. If WAAS cannot meet this requirement, FAA may incur additional costs to install local area augmentation systems at more airports than expected. A decision is expected on any needed procedural changes by late 1998. The addition of one or two GEO satellites would increase the program cost beyond the current estimate of $2.4 billion. FAA expects that adding one or two GEO satellites would cost between $71 million and $192 million over the WAAS life cycle (2001-2016). Full Cost Savings From WAAS Tied to FAA’s Decommissioning of Ground-Based System

To get the full cost savings from WAAS, FAA will need to decommission its ground-based network of navigation aids, which now costs the agency $166 million annually to maintain. FAA’s plan presumes that both its current ground-based system and the new satellite-based system will be in place from the time that the full, Phase 3 WAAS is commissioned until the decommissioning of the ground-based network is completed in 2010. Nevertheless, FAA’s plans could be impeded if the WAAS program’s schedule slips or if safety and economic benefits are not sufficient to cause the aviation industry to switch quickly to satellite technology. Cost Increases and Delays in Decommissioning Reduce Net Benefits of WAAS, but Benefits Still Exceed Costs

In making investment decisions, FAA conducts benefit-cost analyses to determine if the benefits to be derived from acquiring new equipment outweigh the costs. To understand the impact of the potential cost increases and decommissioning delays previously discussed, we requested that FAA’s support contractor perform alternative runs of the benefit-cost analysis.FAA’s 1997 analysis served as the base case for comparison purposes. Using these assumptions, the contractor’s analysis found that the benefit-cost ratio would be 4.6 when passenger time savings were included and all aircraft gained savings from shorter flights and 1.7 when passenger time savings were excluded and 30 percent of all aircraft gained savings from shorter flights. However, delays in decommissioning or the retention of ground-based navigation aids would cause substantial decreases in the net benefits of the WAAS program.
Why GAO Did This Study

GAO discussed the Federal Aviation Administration's (FAA) Wide Area Augmentation System (WAAS) program, focusing on: (1) the likelihood of WAAS satisfying key performance requirements within current program cost and schedule estimates; (2) the importance of avoiding delays in FAA's timetable for shutting down (decommissioning) ground-based navigation aids; and (3) the potential impact of cost increases and decommissioning delays on the benefit-cost analysis for the WAAS program.

What GAO Found

GAO noted that: (1) while the developers of WAAS and outside experts are confident that WAAS is likely to satisfy most key performance requirements within current program cost and schedule estimates, some concerns are worth noting; (2) specifically, FAA may make some procedural changes for aircraft landings if WAAS is not able to deliver the level of service provided by existing ground-based landing systems; (3) also, FAA may add more space-based equipment to meet performance requirements; (4) FAA expects to make decisions on these matters by late 1998 and late 2000, respectively; (5) if the space-based equipment is added, program costs would grow between $71 million and $192 million above the current total program cost estimate of $2.4 billion; (6) the program's schedule can be expected to slip if arrangements are not made immediately to put this equipment in space; (7) to realize the full cost savings from WAAS, FAA will need to avoid delays in decommissioning its ground-based network of navigation aids; (8) FAA estimates that it incurs costs of $166 million annually to maintain this ground-based network; (9) FAA's plans--which envision complete decommissioning of the network by 2010--presume that the full WAAS will become operational (commissioned) in 2001 and that the aviation industry will install the necessary equipment in its aircraft during the remainder of that decade; (10) however, the planned decommissioning could be delayed if the WAAS program's schedule slips or if safety and economic benefits, such as an aircraft's ability to take advantage of more fuel-efficient routes, are not sufficient to cause the industry to switch to satellite-based navigation technology by the end of the next decade; (11) cost increases and decommissioning delays, if they occur, would reduce the net benefits of the WAAS program, but program benefits would still outweigh costs; (12) FAA's July 1997 benefit-cost analysis found that benefits were: (a) more than five times greater than costs when passenger time savings were included and all aircraft gained savings from shorter flights; and (b) more than two times greater than costs when passenger time savings were excluded and 30 percent of all aircraft gained savings from shorter flights; (13) additional analyses done at GAO's request, using pessimistic cost and decommissioning assumptions, found that the WAAS program's benefits are still significantly greater than the costs; and (14) however, if the ground-based navigation network is not decommissioned or must remain in place much longer than expected, the net benefits from WAAS would be substantially reduced.