DoD Permanently Discontinues Procurement Of Global Positioning System Selective Availability


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Mon, 17 Sep 2007 23:00:00 -0500

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September 18, 2007


Dod Permanently Discontinues Procurement Of Global Positioning System Selective Availability

The Department of Defense announced today that it intends to stop procuring Global Positioning System (GPS) satellites with the capability to intentionally degrade the accuracy of civil signals.
This capability, known as Selective Availability (SA), will no longer be present in the next generation of GPS satellites.
Although the United States stopped the intentional degradation of GPS satellite signals by setting SA levels to zero in May 2000, this action to permanently remove SA eliminates a source of uncertainty in GPS performance that has been of concern to civil GPS users worldwide for some time. While this action will not materially improve the performance of the system, it does reflect the United States' strong commitment to users by reinforcing that this global utility can be counted on to support peaceful civil applications around the globe.
The decision to remove the capability from the next generation GPS satellites was approved by the President after a recommendation from DoD. The move coincides with the U.S. Air Force's solicitation to purchase the next generation of GPS satellites known as GPS III.
GPS is a dual-use, satellite-based system that provides accurate positioning, navigation and timing information to users worldwide. Originally developed by the Department of Defense as a military system, GPS has become a global utility. It benefits users around the world in many different applications, including aviation, road, marine and rail navigation, telecommunications, emergency response, resource exploration, mining and construction, financial transactions and many more.

Glad SA is gone

Just don't think that because SA is going away that we have made ourselves more vulnerable. I wouldn't doubt that there are GPS jamming capabilites that will prevent accurate target guidance for high-value "targets."

GPS Accuracy

Mariner Joe:

I don't think that even if the accuracy was reduced, to oh say a radius of one mile, that this makes us any safer and would only make the GPS system useless. Launching any type of nuclear device, whether a conventional bomb or dirty bomb, that lands within one mile of its target is still devastatingly effective. The same goes for a chem-bio device. I think (hope) DoD has come to the same conclusion. The only way to eliminate this risk would be to eliminate the GPS system - and that we know isn't going to happen.

Just my $0.02 worth.


Officer I'm sorry I was going the wrong way on that one-way street but my GPS told me to turn left ... Oh, I'm still getting a ticket, okay then the GPS will see ya in court!

GPS Accuracy

While I agree with you that a conventional nuclear device landing within a radius of one mile would still have a devastating affect on a target, the same cannot be said for a dirty bomb or even a chem-bio type weapon. So much would have to do with the type of isotope used (in the case of a dirty bomb) or the type of chemical biological agent used (chem-bio attack). Both would be subject to ambient temperatures, prevailing winds, humidity, etc.

The purpose of intentionally degrading GPS signals near high value targets would be more for conventional weapons and terrorist activities. No one is fully expecting terrorists to have nuclear capabilities (possibly dirty bombs but these are MUCH less devastating and harder to deploy with enough accuracy to ensure casualties) Some conventional MANPAD missile systems are GPS guided and even conventional mortars could use GPS targetting. Sensitive facilities may locally jam GPS signals in their immediate vicinity for these reasons. Some users have rightly noticed a loss of GPS signal near the Pentagon for example.

Just my take on it.

If I recall correctly, the

If I recall correctly, the DoD basically agreed to turn off Selective Availability YEARS ago. Want to say late 70s, but I don't remember off hand. Could be 80s.

My reading of this basically says is that new satellites will not have that old capability. Probably because, if needed, there are other ways of handling it. I.e. the big off switch or encrypted signals or some such.