GPS Policy - Selective Availability
Conceived in the 1970s, the Global Positioning System (GPS) was originally built for military use. GPS remained a military-only technology until the early 1980s, when President Reagan decided the technology could be adapted for public use, as well. By the early 1990s, civilians could buy GPS equipment that was accurate within only about 300 feet. This inaccuracy was due to the deliberate distortion of the signal in order to prevent civilian gear from being used in a military attack on the U.S. This was called Selective Availability (SA).
On May 1, 2000, President Clinton signed an order ending SA as part of an on-going effort to make GPS more attractive to civil and commercial users worldwide. Now, GPS is accurate within 40 feet, or much better. Military GPS is even more precise and has a margin of error of only a few centimeters.
The end of Selective Availability was a major turning point that has helped GPS to become a global utility, now being used around the world in many different applications.
After the attacks of September 11th, the industry buzzed over the possibility of a return to SA. However, on Sept. 17, 2001, the Interagency GPS Executive Board (IGEB), which governed the GPS system at that time, announced the United States has no intent to ever use Selective Availability again.