All segments are  needed to take full advantage of GPS capabilities. The Air Force Continues to Face Challenges to Launching Its Satellites as Scheduled, Which Could Affect the Availability of the Baseline GPS Constellation

The Air Force faces challenges to launching its IIF and IIIA satellites as  scheduled. The GPS IIIA program is progressing and the Air  Force continues to implement an approach that should prevent the types  of problems experienced on the IIF program. However, the IIIA schedule  remains ambitious and could be affected by risks such as the program’s  dependence on a ground system that will not be completed until after the  first IIIA launch. Meanwhile, the availability of the baseline GPS  constellation has improved, but a delay in the launch of the GPS IIIA  satellites could still reduce the size of the constellation to below its 24- satellite baseline, where it might not meet the needs of some GPS users. After Long Development Delays, the First GPS IIF Satellite Has Been Launched, but the Program Faces Longer-Term Challenges in Launching IIF Satellites as Scheduled

Last year, we reported that under the IIF program, the Air Force had  difficulty successfully building GPS satellites within cost and schedule  goals, encountered significant technical problems that threatened its  delivery schedule, and faced challenges with a different contractor for the  IIF program. Since our last review, launch of the first IIF satellite was postponed an  additional 6 months—for an overall delay of almost 3-½ years—to May  2010. Current GPS Constellation Availability Improves, but a Delay in GPS III Could Affect GPS Constellation Performance

To ensure that the GPS constellation can provide PNT information to GPS  users located anywhere on the earth at almost any time of day, the  performance standards for both (1) the standard positioning service  provided to civil and commercial GPS users and (2) the precise positioning  service provided to military GPS users commit the U.S. government to at  least a 95 percent probability of maintaining a constellation of 24  operational GPS satellites. Exploitation of New Satellite Capabilities Delayed Further Because of Ground Control and User Equipment Delays and Acquisition Challenges

GPS modernization efforts across the space, ground control, and user  equipment segments introduce new capabilities, such as improved  resistance to jamming and greater accuracy. However, the development of GPS ground  control systems has experienced years of delay and in some cases will  delay the delivery of new capabilities to users. In addition, although the  Air Force has taken steps to enable quicker procurement of military GPS  user equipment, there are significant challenges to these systems’  implementation. DOD has taken some steps to coordinate GPS segments, but it is not likely  that these will be sufficient to ensure that all GPS segments are  synchronized to the maximum extent practicable, which we recommended  last year. The GPS Interagency Requirements Process Is Relatively Untested and Lacks Detailed Guidance

The GPS interagency requirements process remains relatively untested  and civil agencies continue to find the process confusing. The lack of  detailed guidance on the process is a key source of confusion and has also  contributed to other problems, such as disagreement and inconsistent  implementation of the process. In addition, we found that the interagency  requirements process relies on individual agencies to identify their own  requirements but does not identify PNT needs across civil agencies. Both DOD and DOT concurred with this recommendation. 3. State Department officials also  stated that they continue to engage other planned global navigation  satellite system providers bilaterally and multilaterally in pursuit of  interoperability with civil GPS signals and compatibility with GPS military  signals. Moreover, this year we found that a lack of comprehensive guidance on  the GPS interagency requirements process is a key source of this  confusion. DOT  generally agreed to consider our recommendation. Appendix I: Scope and Methodology

In order to assess the status of the U.S. Air Force’s efforts to develop and  deliver new Global Positioning System (GPS) satellites, the availability of  the GPS constellation, and the potential impacts on users if the  constellation availability diminishes below its committed level of  performance, we performed several tasks. To assess the GPS interagency requirements process, we (1) reviewed and  analyzed guidance on the process and documents related to the status of  civil requirements and (2) interviewed officials from the National  Aeronautics and Space Administration; the Department of Transportation,  including the Federal Aviation Administration; the Department of  Commerce, including the National Oceanic and Atmospheric  Administration and the National Institute of Standards and Technology;  the Coast Guard; the Office of the Assistant Secretary of Defense,  Networks and Information Integration; the National Security Space Office;  the Air Force Space Command; the Interagency Forum for Operational  Requirements; and the National Coordination Office for Space-Based  Positioning, Navigation, and Timing.
Why GAO Did This Study

The Global Positioning System (GPS) provides positioning, navigation, and timing (PNT) data to users worldwide. The U.S. Air Force, which is responsible for GPS acquisition, is in the process of modernizing the system. Last year GAO reported that it was uncertain whether the Air Force could acquire new satellites in time to maintain GPS service without interruption. GAO was asked to assess (1) the status of Air Force efforts to develop and deliver new GPS satellites, the availability of the GPS constellation, and the potential impacts on users if the constellation availability diminishes below its committed level of performance; (2) efforts to acquire the GPS ground control and user equipment necessary to leverage GPS satellite capabilities; (3) the GPS interagency requirements process; and (4) coordination of GPS efforts with the international PNT community. To do this, GAO analyzed program documentation and Air Force data on the GPS constellation, and interviewed officials from DOD and other agencies.

What GAO Found

The Air Force continues to face challenges to launching its IIF and IIIA satellites as scheduled. The first IIF satellite was launched in May 2010--a delay of 6 additional months for an overall delay of almost 3 1/2 years--and the program faces risks that could affect subsequent IIF satellites and launches. GPS IIIA appears to be on schedule and the Air Force continues to implement an approach intended to overcome the problems experienced with the IIF program. However, the IIIA schedule remains ambitious and could be affected by risks such as the program's dependence on a ground system that will not be completed until after the first IIIA launch. The GPS constellation availability has improved, but in the longer term, a delay in the launch of the GPS IIIA satellites could still reduce the size of the constellation to fewer than 24 operational satellites--the number that the U.S. government commits to--which might not meet the needs of some GPS users. Multiyear delays in the development of GPS ground control systems are extensive. In addition, although the Air Force has taken steps to enable quicker procurement of military GPS user equipment, there are significant challenges to its implementation. This has had a significant impact on DOD as all three GPS segments--space, ground control, and user equipment--must be in place to take advantage of new capabilities, such as improved resistance to jamming and greater accuracy. DOD has taken some steps to better coordinate all GPS segments. These steps involve laying out criteria and establishing visibility over a spectrum of procurement efforts. But they do not go as far as GAO recommended last year in terms of establishing a single authority responsible for ensuring that all GPS segments are synchronized to the maximum extent practicable. Such an authority is warranted given the extent of delays, problems with synchronizing all GPS segments, and importance of new capabilities to military operations. As a result, GAO reiterates the need to implement its prior recommendation. The GPS interagency requirements process, which is co-chaired by officials from DOD and DOT, remains relatively untested and civil agencies continue to find the process confusing. This year GAO found that a lack of comprehensive guidance on the GPS interagency requirements process is a key source of this confusion and has contributed to other problems, such as disagreement about and inconsistent implementation of the process. In addition, GAO found that the interagency requirements process relies on individual agencies to identify their own requirements rather than identifying PNT needs across agencies. The Department of State continues to be engaged internationally in pursuit of civil signal interoperability and military signal compatibility, and has not identified any new concerns in these efforts since GAO's 2009 report. Challenges remain for the United States in ensuring that GPS is compatible with other new, potentially competing global space-based PNT systems.

What GAO Recommends

GAO recommends that the Department of Defense (DOD) and the Department of Transportation (DOT) develop comprehensive guidance for the GPS interagency requirements process. DOD did not concur with the recommendation, citing actions under way. DOT generally agreed to consider it. GAO believes the recommendation remains valid.