Going Mainstream - GPS Declassified: From Smart Bombs to Smartphones - page 127

it resisted plans backed by the faa and the International Air Transport Asso-
ciation to build a Wide Area Augmentation System (waas) that would use
multiple reference stations and separate non-gps communications satellites
to broadcast corrected signals to airplanes across the entire continent. 35
As the Pentagon and Department of Transportation tried to resolve their
differences, U.S. officials repeatedly sought to reassure the private sector, par-
ticularly the huge civil aviation market. The faa administrator, in a letter to
the icao's Tenth Air Navigation Conference in September 1991, pledged to
make the Standard Positioning Service available to the international commu-
nity at no charge for at least ten years (starting in 1993). 36 Other than specify-
ing a time frame, this was essentially the same offer President Reagan had
made a decade before. The faa repeated that pledge at icao assemblies in
1992 and 1994, assuring provision of sps for the “foreseeable future,” subject
to available funds, and additionally promising to provide at least six years of
advance notice before terminating gps or eliminating sps. 37
All of this activity occurred before gps was officially complete. Not until
June 1993, almost twenty years after the Defense Systems Acquisition Review
Council authorized the program, was the full constellation of twenty-four sat-
ellites orbiting the earth. Following several months of testing, Secretary of
Defense Les Aspin declared Initial Operational Capability (ioc) in a Decem-
ber 8 letter to the Department of Transportation. After nearly a year and a
half of further testing, the Air Force declared Full Operational Capability (foc)
in April 1995. 38 These actions were not mere ribbon-cutting-style announce-
ments; they were formal certifications that the system met specific criteria for
accuracy and reliability—for example, accurate horizontal positioning within
one hundred meters 95 percent of the time. The foc declaration assured autho-
rized users of the Precise Positioning Service that pps met its more-stringent
requirements, which was of significance to U.S. military forces and allies. The
ioc certified that sps met standards set forth in the Federal Radionavigation
Plan, a technical planning and policy document prepared jointly by the Defense
and Transportation Departments every two years. One practical effect was to
designate gps receivers as satisfying federal maritime regulations requiring
ship-borne electronic position fixing devices. 39 Such devices enable vessels
to report their position manually or automatically to avoid accidents, such as
in fog. In March 1999 the Coast Guard activated an augmentation system
called the Maritime Differential gps Service. It consisted of a control center
and network of radio beacons for enhanced navigational accuracy along the