The timely replacement of aging GPS satellites was a major concern of the U.S. Government Accounting Office (GAO) in a May report and testimony before U.S. House subcommittee.

Following the GAO report, officials at the U.S. Peterson Air Force Space Command sought to assure the public the the GPS system would not fail, but did say there was some potential risk of degradation in GPS performance.

GAO predicted that system degradation could have wide-ranging impacts, including reducing accuracy of precision-guided munitions using GPS to strike their targets, or reducing the accuracy of emergency 911 communicatons systems. Also, airlines might have to delay, cancel or reroute flights.

The GPS system, now comprised of 30 satellites used to help in navigation, is undergoing an upgrade expected to cost the federal government $6 billion over the next five years. The system is used by the U.S. military, but also commercial ship and plane pilots, and millions of motorists.

Boeing said today that it has shipped one satellite to Cape Canaveral Air Force Station in Florida for tests considered key to the Air Force'ss deployment of a next-generation GPS system that would reduce the probability of system degradation.