Clarification about the term "GPS Shutdown"

How do you know when it's noon without a clock?

The only way I can think of is to plot the movement of the sun over an
entire day. You can then see true north plotted directly. But an
entire day is a long time to wait. And if you are moving, that won't
help.

What if it's daytime?

Not if they keep their eyes open.

GPS receivers?

 

Five hours is an extremely long time.

Years from now, people will be saying exactly the same thing, except
that it will be a £1 GPS receiver from a junk shop, instead of a watch.

You need destination coordinates, and your coordinates.

You can ask someone who lives there.

So? It was part of what proved the value of GPS to me.

 

I'm just using the same reasoning being used to argue against GPS.

What if GPS fails?

Well, what if VOR fails? Or ADF? Or the magnetic compass?

The fact is, they are all more or less equally vulnerable, but human
nature is such that people will tend to reject what's new, rather than
what's old. They believe that anything new is less reliable, whether
this is actually the case or not.

 

A human being, or a signal from a computer.

 

Components aren't good enough.

 

To maintain RNP 10 tracks over the oceans, an INS needs an

THAT IS NOT THE ONLY WAY. RPN 10 approval requires an airline to demonstrate
it's equipment meets certian accuracy requirements. Meeting those requirements
allows 6.2 hours of flight without position updates. Several means of updating
or increasing INS/IRS accuracy are mentioned, GPS is one but not the ONLY one.
See: http://www.faa.gov/ats/ato/rnp.htm
Quote from FAA order 8400.12A --- .
Effect of En route Updates. Operators may extend their RNP-10 navigation
capability time by updating. Approvals for various updating procedures are
based upon the baseline for which they have been approved minus the time
factors shown below:

(1) Automatic updating using DME/DME = Baseline minus 0.3 hours (e.g., an
aircraft that has been approved for 6.2 hours can gain 5.9 hours following an
automatic DME/DME update).

(2) Automatic updating using DME/VOR = Baseline minus 0.5 hours.

(3) Manual updating using a method similar to that contained in Appendix 7 or
approved by AFS-400 = Baseline minus one hour.

GPS is listed as a SUPPLEMENTAL navigation system by the FAA - aircraft can
still navigate without it. Maybe someday GPS will be required on aircraft, but
not now.

 

The majority of the airports in the world (and in the USA) don't

Is that so? I would think that every airport in the world that passenger
airlines land at would have an ILS (instrument landing system = localizer and
glideslope). WOW. Don't ever fly on a rainny day! Maybe you'rer referring to
county airports and dirt airstrips?

 

Anybody got a back issue of that british newspaper? ;-)


Juergen Nieveler

 

Which is why they have more than one backup...

For the ATC, another radar. Or if everything breaks down, they might
call the Pentagon and ask them to launch an AWACS bird if they're
really desperate.

If you were going in the right direction before the outage, why should
you suddenly be flying circles?

GPS isn't primary navigation yet, though.


Juergen Nieveler

 

During a day it's not all that bad - you can usually still see the sun
through the clouds.

And if you're lost in the woods on a cloudy night, that light polution
might prevent you from seeing the stars, but it tells you the direction
to the next city


Juergen Nieveler

 

Not nearly an entire day needed. Once it got to the highest position,
you'll note it going down again.

You use all those other methods we keep telling you

But you'd at the very least have to make huge detours - imagine a
terrain like grand canyon, with a map you can plan your route ahead.

Maps.


Juergen Nieveler

 

Turning a crank, after pre-heating the cylinders with a match? Hint:
Most diesel engines today are started electrically...


Juergen Nieveler

 

There are churches with the choir and altar in the west? Got to be
pretty rare, at least in catholic areas.


Juergen Nieveler

 

Join the boyscouts. You findout where north is, orient your map, look
at the area around you for noticeable features (and on a 1:25000 map,
that includes trees), and fix your initial position. Easy. BTDT.

If your batteries run out, you're out of luck.

Juergen Nieveler

 

Just how did the pilgrims manage to find the USA? And why didn't
anybody stop them?

Juergen Nieveler

 

Look at the direction people are praying in, then.

If you don't even know THAT, you're screwed. Your GPS won't help you if
you suddenly find yourself on the wrong planet.

Not necessarily. You can measure height of the sun over the horizon -
highest position is noon.

You don't even know THAT? Just how old are you, 8?

We could set you up on a normal field exercise, basic-training-style -
we'd send out a search team after a couple of days, don't worry.

And if you get thrown out of a plane with just the order "Reach the
city of $FOO", you're still screwed.

You realise that you can't compare geocaching with real field trips,
let alone army exercises?

Wrong. If you know your position and know where you want to go, you'll
end up next to that huge river and drown in a patch of quicksand -
which you would have known if you had a map.


Juergen Nieveler

 

I grew out of that long ago. I don't think I'd find the organization
interesting, especially if it is still depending on the moss on trees
for navigation.

 

They sailed due west from a known point in Europe.

Why would anyone want to?

 

How? And what if you start at dawn?

The detour is the same, though.

 

In which direction do Christians pray?

I guess the methods you suggest aren't valid for the tropics, then.

Not if you are moving.

Which one is the polar star?

Why would I want such blast to the distant past? Nobody navigates with
moss and stars today. Neither method is certified by the FAA, either.

Why would that happen?

Why are any of these being discussed? None of them is a terrorist
activity, and none of them is a frequent use of navigation among
civilians.

Maps are notoriously unreliable. Direct observation works better.