U.S. lawmakers and industry experts are critical of President Obama’s plan to shut down a decades-old navigation system that could serve as a backup to the Global Positioning System (GPS), the backbone of the Federal Aviation Administration’s Next Generation Air Transportation System (NextGen).
The U.S. government provides GPS service free of charge and plans to invest more than $5.8 billion over the next five years in the GPS satellites and ground control segments. A modernization effort includes GPS IIF and IIIA, two satellite acquisition programs that are to provide new space-based capabilities and replenish the satellite constellation. There are currently 31 active GPS satellites orbiting 12,600 miles above the Earth, and at least 24 operational satellites are needed to provide optimal accuracy in calculating a user’s position.
At issue is the reliability, availability and vulnerability of the in-service GPS satellite constellation, which is already being used to provide air traffic navigation in remote locations, pinpoint targets for precision guided munitions and guide hikers and drivers to their destinations. Also under debate is what existing navigation system is needed to supplement GPS, if any.
President Obama’s 2010 federal budget proposes to cut all funding for the Loran-C navigational system, shaving $35 million in 2010 and $190 million over five years.
Loran-C consists of a chain of 24 land-based, low frequency radio transmitters in the continental United States that send out precise times and coordinated signals. It provides navigation, location and timing services for both civil and military air, land and marine users. It currently serves as a supplemental air navigation system.
Obama called for the cancellation of the program despite the Department of Homeland Security’s (DHS) endorsement of a plan to upgrade the Loran-C system as a backup to GPS. The new system would be known as eLoran.
In February 2008, DHS announced its support for eLoran as an independent national positioning, navigation and timing system that would complements GPS in the event of an outage or disruption in service.
It said “eLoran will mitigate any safety, security, or economic effects of a GPS outage or disruption. eLoran system will be an enhanced and modernized version of Loran-C, long used by mariners and aviators and originally developed for civil marine use in coastal areas. In addition to providing backup coverage, the signal strength and penetration capability of eLoran will provide support to first responders and other operators in environments that GPS cannot support, such as under heavy foliage, in some underground areas, and in dense high-rise structures. The system will use modernized transmitting stations and an upgraded network.”
The Obama administration is proposing to terminate the long-range radio navigation system operated by the U.S. Coast Guard, saying it is “obsolete” technology. “Loran-C is a federally-provided radio navigation system for civil marine use in U.S. coastal areas. The Nation no longer needs this system because the federally supported civilian Global Positioning System (GPS) has replaced it with superior capabilities. As a result, Loran-C, including recent limited technological enhancements, serves only the remaining small group of long-time users. It no longer serves any governmental function and it is not capable as a backup for GPS,” the Office of Management and Budget (OMB) stated.
“Several federal agencies, including the Departments of Defense, Transportation, and Homeland Security, already have backup systems for their critical GPS applications and the termination of Loran-C does not foreclose future development of a national backup system. It merely stops the outflow of taxpayer dollars to sustain a system that does not now and will not, in its current state, serve as a backup to GPS,” the OMB added.
Senator Jay Rockefeller (D-WV) chairman of the Committee on Commerce, Science and Transportation, advocates continuing the Loran system, saying it is the best backup to GPS. Rockefeller sees “the need to maintain Loran-C while transitioning to enhanced Loran as a means to enhance the homeland security, marine safety and environmental protection missions of the Coast Guard.”
Senator Susan Collins (R-Maine) says” “discontinuing the entire program would leave the nation without a backup to the GPS program, wasting millions of dollars already spent on this system.” To bolster her case, Collins cited a new General Accountability Office (GAO) study that warns that delays in launching new GPS satellites could imperil the performance of the navigational system.
“It is uncertain whether the Air Force will be able to acquire new satellites in time to maintain current GPS service without interruption. If not, some military operations and some civilian users could be adversely affected,” the GAO report has concluded.
It said: “The USAF has struggled to successfully build GPS satellites within cost and schedule goals; it encountered significant technical problems that still threaten its delivery schedule; and it struggled with a different contractor. As a result, the current (Boeing) IIF satellite program has overrun its original cost estimate by about $870 million and the launch of its first satellite has been delayed to November 2009–almost three years late. “
Furthermore, “while the Air Force is structuring the new (Lockheed Martin) GPS IIIA program to prevent mistakes made on the IIF program, the Air Force is aiming to deploy the next generation of GPS satellites three years faster than the IIF satellites. GAO’s analysis found that this schedule is optimistic, given the program’s late start, past trends in space acquisitions, and challenges facing the new contractor. Of particular concern is leadership for GPS acquisition, as GAO and other studies have found the lack of a single point of authority for space programs and frequent turnover in program managers have hampered requirements setting, funding stability, and resource allocation,” the GAO report added.
“If the Air Force does not meet its schedule goals for development of GPS IIIA satellites, there will be an increased likelihood that in 2010, as old satellites begin to fail, the overall GPS constellation will fall below the number of satellites required to provide the level of GPS service that the U.S. government commits to,” the GAO has concluded.
Boeing says “GPS IIF will deliver more capability and improved mission performance to military and civilian users. Working very closely with the Air Force and its team, Boeing has taken aggressive steps to resolve the technical issues on IIF with a strong emphasis on mission assurance.
“Design changes were required to ensure performance over the satellite design life and have caused schedule delays, but these changes are in the final phase of implementation and a fully integrated satellite (SV1) has already successfully completed the thermal-vacuum test program – the most stressing system level test. SV2 was shipped to the Cape on May 6 to perform system-level compatibility tests and serve as a risk reduction pathfinder for SV1 processing later this year.
“We are on track to deliver SV1 to the Air Force later this year for the first IIF launch. The Operational Control Segment was put into service in 2007 and has been successfully flying the current GPS constellation and will also support the IIF series of satellites,” Boeing added.
Meanwhile, the Lockheed Martin-led team has successfully completed the GPS III Preliminary Design Review (PDR), a major program milestone that allows the team to begin the Critical Design Review (CDR).
“GPS III will improve position, navigation and timing services and provide advanced anti-jam capabilities yielding superior system security, accuracy and reliability,” the firm said. The team is working under a $3 billion contract awarded in May 2008 to produce up to 12 GPS IIIA satellites, with first launch projected for 2014.
Lockheed Martin says “the next generation GPS IIIA satellites will deliver significant improvements over current GPS space vehicles, including a new international civil signal (L1C) and increased M-Code anti-jam power with full earth coverage for military users.”
A study requested by the Department of Transportation (DOT) in August 2006 and completed in March 2007 by an Independent Assessment Team (IAT) commissioned by the Institute of Defense Analyses (IDA) and publicly released in January 2009 recommended that the U.S. Government complete the eLoran upgrade and commit to eLoran as the national backup system to GPS for the next 20 years. Based on the IAT report, DOT and the Department of Homeland Security (DHS) jointly recommended that eLoran be the national backup for GPS.
The IAT maintains that “eLoran is the only cost-effective backup for national needs; it is completely interoperable with and independent of GPS, with different propagation and failure mechanisms. … It is a seamless backup, and its use will deter threats to U.S. national and economic security by disrupting (jamming) GPS reception.”
It is unclear whether the fiscal 2010 budget proposal actually zeros out funding for eLoran and DHS may end up a key player in keeping eLoran alive. DHS plans to complete a review of GPS backup systems in June.
The military uses GPS to direct “smart” bombs and missiles and the GAO report warned that decreased performance could have an impact on military strikes.
“The accuracy of precision guided munitions that rely upon GPS to strike their targets could decrease,” the GAO said. “The risks of collateral damage could also increase. Disruptions in service could require military forces to either use larger munitions or to use more munitions on the same target to achieve the same level of success.”
Furthermore, said the GAO, “intercontinental commercial flights use predicted satellite geometry over their planned navigation route, and may have to delay, cancel, or reroute flights. Enhanced 911 services, which rely on GPS to precisely locate callers, could lose accuracy particularly when operating in urban canyons or mountainous terrain.”
Patrick Forrey, President of National Air Traffic Controllers Association (NATCA), said “NATCA is concerned that the (NextGen) system being proposed by the FAA, which is centralized and lacking a viable backup, is unacceptably vulnerable to attack or natural disaster. Human intervention must not be the only layer of redundancy. The FAA must build redundancy into the system in order to ensure that safety is not compromised in the event of an attack, natural disaster, or technological failure.”
Concerns over GPS vulnerability to jamming surfaced in the late 1990s. A landmark report mandated by a presidential decision directive and prepared by DOT’s Volpe National Transportation Systems Center concluded: GPS is susceptible to disruption from such causes as atmospheric effects, signal blockage from buildings, and interference from communications equipment.”
Furthermore, “the GPS signal is subject to degradation and loss through attacks by hostile interests. Potential attacks cover the range from jamming and spoofing of GPS signals to disruption of GPS ground stations and satellites,” it stated. The Volpe study concluded that affordable backups to GPS needed to be developed.
The report caused the FAA and other federal government agencies to consider the adequacy for backup systems to GPS, including Loran-C, inertial navigation systems, “skeleton” VHF omni-range/distance-measuring equipment (VOR/DME) systems and an anti-jam GPS antenna developed by the military.
The FAA acknowledged that the low-power GPS signal was susceptible to interference. It said: “The potential exists for an individual or organization to jam GPS and cause a loss of service over a large area.”
But an independent risk assessment by the Johns Hopkins University Applied Physics Laboratory concluded that with some improvements and augmentation, GPS could serve as the sole basis for radio navigation by 2010. It said threats to GPS signal reception could be managed and that unintentional interference was not a major risk factor.
It deemed intentional interference the largest risk area, but noted that planned avionics were designed to rapidly detect the onset of such a threat. As aircraft can be vectored away from jammed regions, the threat poses no safety risk, though traffic flow disruptions might follow. The study said methods to detect and stop GPS jammers must be put in place. GPS jammer technology is readily available, with a Russian company known to have developed a low-cost jammer.
Michael Harrison, a consultant with Aviation Management Associates in Alexandria, VA, warns against placing all reliance on GPS. “A number of technical issues makes me very uncomfortable with GPS. The answer in my mind is for the government to declare a backup system for GPS and hurry up and build it.” Added Harrison: “The cheapest answer is eLoran.”