Haddo underwent and intensive Selective Restricted Availability in October 1985 in San Diego.

Initially, the highest quality signal was reserved for military use, and the signal available for civilian use was intentionally degraded (Selective Availability).

On May 2, 2000 "Selective Availability" was discontinued as a result of the 1996 executive order, allowing users to receive a non-degraded signal globally.

In the spring of 2000, the U.S. government discontinued Selective Availability, its practice of degrading publicly-available GPS signals.

However, the military developed technology that would allow them to scramble GPS signals over sensitive areas, so Selective Availability became obsolete.

This enhanced data allowed for considerably enhanced system accuracy (not unlike Selective Availability under GPS).

Selective Availability is still a system capability of GPS, and could, in theory, be reintroduced at any time.

But until 2000, the U.S. government practiced something called Selective Availability, which meant they purposefully degraded the information that civilian GPS systems were able to receive.

In theory the GPS signal with Selective Availability turned off offers accuracy on the order of 3 m. In practice, typical accuracy is about 15 m.

After Selective Availability was turned off by the U.S. government, the largest error in GPS was usually the unpredictable delay through the ionosphere.