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It seems worth mentioning that the last time GPS had issues like this afaik, it was due to the US utilizing 'selective availability' due to national security issues. We used it somewhat famously during the 9/11 attacks.

Also the page 404's via archive.org, but information formerly from gps.gov can still be found here: https://archive.ph/trwOo

Edit: The selective availability page moved to https://www.gps.gov/selective-availability

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> We used it somewhat famously during the 9/11 attacks.

I have not been able to locate any source that backs up this claim.

Indeed, the link in the parent even says it hasn't been used since May 2000. So, yeah, it certainly wasn't used "famously".

Perhaps the commenter is thinking of the fact it was used globally prior to May 1, 2000. From a civilian point of view, GPS appeared to be invented around this time but it had actually been available for a couple of decades already, just in a degraded form that wasn't very useful.

> just in a degraded form that wasn't very useful

Differential GPS was already in widespread use in many counties by 2000, which made "selective ability" pointless at it provided automatic corrections to the 'degraded' GPS signal.

https://en.wikipedia.org/wiki/Differential_GNSS

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