GPS Shutdown in time of US "National Crisis"
 

Guess if you're IMC in Buttholenowhere you could be a spot of bother.

Netscape/CNN Article

Ah,it would be a delight to all those who yearn for the glory days of VOR-whoring. Just turn off the INS first.

Because of Selective Service, I doubt anybody would try a serious pond hop without something to back up the GPS.

Thats why the EU are developing their own version of GPS. For once a sensible and strategic use of our tax euros.

I think I heard that there is an agreement to shut down both in "time of war." Could be wrong, though. Might make sense if you consider that what's the point of you having the ability to turn off your GPS if the enemy can simply use the other guy's.

Hmm, I guess the Europeans really don't know about the ability of the DoD to turn off the VOR's/DME's, NDB's, ILS's ...etc, in time of national emergency either.
Gosh, its been this way since the late 1950's and was put in place under Eisenhower.

News travels slowly, I guess.

I wouldn't just generalise "just Europeans" there 411A. I wonder how many pilot types (especially the weekend warriors ;) ) that are aware of this in North America.

Yep, this is nothing new, just a "journalist" looking for a headline on a slow news day...

See: http://www.faa.gov/ATpubs/MIL/Apdices/milapd17.html

Hey, thanks for the link Bubba! :ok:

Not all that surprising, when you consider that many road signs in the UK were removed during WW11

...and mostly didn't get put back again afterwards!!!
TOO

What's the point in the US turning off the GPS system in times of war when it was for military reasons the system was developed in the first place. I thought everyone's use of it apart from the military use of it was secondary.

So they're going to spend billions in construction and maintenance of a system that they couldn't use for the sole purpose it was intended.

Ah yes, but they can tell their folks when it's going to be switched off/jammed/interfered with. Presumably this can be done on a second-by-second basis so that the service can seem seamless for their own users but hopelessly inaccurate for the enemy.

You'll all no doubt seen NOTAM from time to time adertising intentional jamming of GPS for military purposes. Hopefully the commercial organisations who have GPS installed take note of this and rely on INS to a greater extent during these times. I know private pilots who rely utterly on their GPS - putting their lives in the hands of someone in a mountain in Colorado with a digit on the 'off' switch!

At least with VOR, NDB, DME ILS we've got our destiny in our own hands to a greater extent (or am I deluding myself again?)

Cheers,
The Odd One

"I wouldn't just generalise "just Europeans" there 411A. I wonder how many pilot types (especially the weekend warriors) that are aware of this in North America.

Or indeed that there is anywhere outside North America?

Yes, in a real war I would indeed expect all radio navigation aids to be turned off. But since both civil airlines and private flying would also be likely to be banned, would it really affect anyone?

Y-code GPS would probably continue - but CA-mode would be off for the duration.....even with SA re-enabled.

Agreed. But the term "national crisis" is a very wide statement.

Still, your good old INS/IRS system should allow you to get close enough to identify the target/skyscraper visually. After all, this worked well enough until GPS came along.

I doubt that the last 2 minutes of the September 11th attacks were done on GPS/FMS.

IMHO, really safety critical GPS will only be possible with all three systems - GPS (indeed differential GPS!), Galileo when it comes on line, and let's not forget GLONASS. If you have three independent satnavs, you're getting somewhere.

I_FORD is completely wrong. GPS is still the responsibility of the US Department of Defense although GPS is now overseen by a committee co-chaired by the Secretary of Defense and the Secretary of Transportation.

See

http://gps.faa.gov/GPSBasics/index.htm

then follow links to

Interagency GPS Executive Board (IGEB)

followed by

U.S. Space-Based Positioning, Navigation, and Timing Policy

This is the full text for the new arrangements for the control of GPS.

Sure I read somewhere that in the Gulf war (the first one) that they were messing around with the sats in order to degrade the service and make it inaccurate for the enemy/lay user.

My recollection of the first Gulf War was that Selective Availablity was turned off (ie the exact opposite of what SA is for) because the US did not have enough military grade receivers to issue to their ground troops and rushed around buying civil receivers which do not read the P-code. Therefore the C/A code had to be kept without SA degradation.

My understanding of GPS is that the channel for use by Civilians can be turned off, or degraded under selective availability, but the known military channel (and the other couple of unpublished channels) remain in use for those with the correct equipment.