While GPS is currently leading the pack in terms of satnav system implementation, at a recent UN International Committee on Global Navigation Satellite Systems conference it was clear that competing systems are getting closer and could overtake it during the next decade. Presentations from Europe, Russia and China described active developments of worldwide satnav constellations, while India and Japan are moving ahead with regional networks. Though their signals will be compatible with GPS, these aren’t simply clones, and Europe’s Galileo, Russia’s Glonass and China’s Compass will offer several capabilities and services not currently available from GPS.
With its first satellite launched in the late 1970s, GPS has certainly been a trailblazer and today supports more than 300 million land, sea and airborne users around the world. Furthermore, the USAF spends some $1 billion per year to ensure consistently improving global performance, replacing older satellites with updated units that have progressively increased its accuracy and reliability.

However, one perceived major shortcoming of the system is that it employs too few satellites. GPS is a 24-satellite system, and while the Air Force diligently works to maintain that number, the military needs only 21, and that’s a concern for civil aviation interests. Although spare satellites are in nearby “parking” orbits, it takes time to move them to replace failed units.

A United Airlines analysis shows that losing just one satellite of the 24 would inhibit many current GPS procedures, including five-nautical-mile en route separation. Losing one in a 27-satellite constellation would have a much less serious impact, while a 30-satellite configuration would be unaffected even if two satellites failed. Galileo, forecast to be operational in 2013, will have 27 satellites, and Glonass and Compass will each have 30, by 2012 and 2016, respectively.

Furthermore, the other satnav systems include or are planned to include more backup in the form of geostationary (GEO) WAAS satellites. While GPS is augmented by two, Galileo has three GEOs; Glonass will have two, possibly three; and Compass could have as many as five. Also, GPS simply provides separate signals for military and civil users, whereas the in-development systems will provide a range of signals tailored to meet various civil user needs, with some including fees for guaranteed performance, and others providing certain types of data communication.

The additional capabilities of non-U.S. satnav systems pose a dilemma for the Department of Defense and the U.S. government as they determine the capabilities of the next-generation GPS III. The first satellite of that system is forecast to be launched in 2015, with its full constellation operational by 2021. Adding more satellites would require a substantial investment, as would adding the services the other systems offer. On the other hand, GPS equipment and services have created valuable export opportunities for U.S. companies, and falling behind would be costly.
In fact, the business potential of satellite navigation has become at least as strong an incentive to foreign system developers as their earlier concerns about total reliance on GPS, owned and controlled by the DOD. A senior European official stated recently that the $12 billion investment in Galileo would be worth more than $600 billion by 2025. By that time, aviation-related services will account for very little of that sum. Last year 40 million GPS “smart” cellphones were sold in Europe alone, and even larger quantities were sold in Asia, along with car navigators and a vast array of other GPS-dependent equipment, much of it locally manufactured.