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Re: GPS...

Posted: 15 Jan 2012, 21:21
by Chris Trott
petermcleland wrote:Thanks for that explanation Chris...I didn't know that selective availability was still used. I was under the impression that it was permanently switched off some years ago.
While normally off, the capability is retained, and utilized on occasion. Primarily they only use it in areas of "unrest" where GPS might be used by people whose interests don't exactly agree with those of the United States, but they also test the system on occasion in other areas to ensure the system is working or to accommodate testing of other systems by users in that area. Here in Texas, we'll get RAIM (Receiver Autonomous Integrity Monitoring) warnings occasionally when certain testing is being conducted at the Raytheon testing centers in Garland and McKinney where the DoD activates selective availability so that Raytheon can test various tracking and guidance systems to see if they still operate properly under those conditions. The tests usually only last an hour or two, but it'll mean that no airplanes can make RNAV approaches using a virtual glideslope during that time as it requires maximum GPS accuracy.

Re: GPS...

Posted: 16 Jan 2012, 00:17
by DaveB
Primarily they only use it in areas of "unrest" where GPS might be used by people whose interests don't exactly agree with those of the United States
Well.. that's just about everywhere then :lol:

I jest CT.. tks for the explanation ;)
ATB
DaveB B)smk

Re: GPS...

Posted: 16 Jan 2012, 01:22
by Chris Trott
Oh believe me, I fear the day that the DoD gets sufficiently irresponsible as to use RAIM degredation and Selective Availability on a large scale. Hopefully as with the Cold War, cooler heads will prevail.

Re: GPS...

Posted: 16 Jan 2012, 10:00
by emfrat
I'm right with you there, Chris!...I'm still puzzled as to how a gash on the port side resulted in a capsize to starboard.
MIkeW

Re: GPS...

Posted: 16 Jan 2012, 11:05
by SkippyBing
emfrat wrote:I'm right with you there, Chris!...I'm still puzzled as to how a gash on the port side resulted in a capsize to starboard.
MIkeW
I think that may be more to do with the way they drove it onto the sandbank to avoid sinking completely, also if the flooding went across the whole width of the ship the free surface effect would make a capsize to either side equally likely.

Re: GPS...

Posted: 16 Jan 2012, 11:20
by jonesey2k
I wonder who will get the job to refloat her. I reckon she will get the chop because who would chose to sail on a ship that has sunk? A shame really, she looks a nice ship.

Re: GPS...

Posted: 16 Jan 2012, 11:26
by TSR2
I reckon she will be refloated too, given a new name, made to look cosmeticly different and sold to the far East or South America. Thats happened before at any rate.

Re: GPS...

Posted: 16 Jan 2012, 11:53
by DaveB
It's no worse than flying an aircraft that's been in a decent prang. If the damage on the Stbd side isn't too bad, I'm sure they can patch the Port side gash and get her upright again. With a build cost of some $380m.. that's a lot of cash to write off :)

ATB
DaveB B)smk

Re: GPS...

Posted: 16 Jan 2012, 11:59
by Garry Russell
Many ships have completly sunk and some were under water a fair time before salvage and repair.

The hulll is the most expensive bit, but strip it down and repair then refit and you're away. :thumbsup:

If they're interested I have an oldish humidifier they can borrow. :)


http://www.history.navy.mil/photos/even ... ph-ca9.htm

Re: GPS...

Posted: 16 Jan 2012, 12:13
by Tomliner
Perhaps not relevant but am I the only one that looks at the vast height of these modern liners with their shallow draughts and feels some uncertainty about their stability? *-) EricT