Have you ever...

"Bob Noel" wrote in message
...
Can't be done. There is no on/off switch.

don't bet on it.

And besides, even if you could bet on it, the GPS receiver itself is a
possible point of failure (and probably more likely than the satellite
network).

Newps wrote:


Suppose you are navigating solely by GPS. What are you going to do in
the event the military chooses to disable the GPS system while you're
airborne

Can't be done. There is no on/off switch.

I'm involved with supporting spacecraft operations of NASA's constellation
of EOS spacecraft. Somewhere, there's a satellite control center that
operates the constellation of GPS spacecraft. It may be true that the
military can't "throw a switch", but there's no doubt that they can
command each satellite to shut itself down and go into "safe hold",
effectively shutting down the GPS system.

--- Jay


--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.oceancityairport.com
http://www.oc-adolfos.com

On 16 Apr 2005 00:26:54 GMT, (Jay Masino)
wrote:

Newps wrote:


Suppose you are navigating solely by GPS. What are you going to do in
the event the military chooses to disable the GPS system while you're
airborne

Can't be done. There is no on/off switch.

I'm involved with supporting spacecraft operations of NASA's constellation
of EOS spacecraft. Somewhere, there's a satellite control center that
operates the constellation of GPS spacecraft. It may be true that the
military can't "throw a switch", but there's no doubt that they can
command each satellite to shut itself down and go into "safe hold",
effectively shutting down the GPS system.

I wrote some articles on GPS for Trimble in the early '80s. I don't
have my notes from then, but there are a few things I sort of remember
that sort of come down evenly on both sides of the debate.

One is that the Navstar system was a joint military/civilian effort,
implying a promise to keep it operational in most circumstances.

The other is that the satellites' orbits have to be tracked and
corrected ephemerides regularly updated with an uplink from the Naval
Observeratory, which I assume is how they can deliberately degrade C/A
coverage over specific geographic areas.

(The NO would have been a single point of failure. By now, there is
probably some redundancy.)

Feel free to bring me up to date.

Don

Don Tuite wrote in
:

On 16 Apr 2005 00:26:54 GMT, (Jay Masino)
wrote:

Newps wrote:


Suppose you are navigating solely by GPS. What are you going to do
in the event the military chooses to disable the GPS system while
you're airborne

Can't be done. There is no on/off switch.

I'm involved with supporting spacecraft operations of NASA's
constellation of EOS spacecraft. Somewhere, there's a satellite control
center that operates the constellation of GPS spacecraft. It may be
true that the military can't "throw a switch", but there's no doubt that
they can command each satellite to shut itself down and go into "safe
hold", effectively shutting down the GPS system.

I wrote some articles on GPS for Trimble in the early '80s. I don't
have my notes from then, but there are a few things I sort of remember
that sort of come down evenly on both sides of the debate.

One is that the Navstar system was a joint military/civilian effort,
implying a promise to keep it operational in most circumstances.

The other is that the satellites' orbits have to be tracked and
corrected ephemerides regularly updated with an uplink from the Naval
Observeratory, which I assume is how they can deliberately degrade C/A
coverage over specific geographic areas.

(The NO would have been a single point of failure. By now, there is
probably some redundancy.)

Feel free to bring me up to date.

Don

A small hobby of mine is satellite observing, so I asked about
this amongst some of those folks and got the following tidbits.

Individual NAVSTAR sats can surely be shut down, aka sleep mode.
This would be necessary in the event of a satellite sending
erroneous data. You need to be able to shut it off to keep the
system working. If they really wanted to, they could put them
all into sleep mode, but that is near nil probability as it
would also deny the military of their use.

However, it may take a few hours to accomplish for any given
sat as it must be within communications range which isn't
100% of the time.

Although President Clinton ordered the 'selective accuracy' mode
to be turned off, it surely can be turned back on again. This
would degrade the accuracy, but the system woudl still be useable.

Also, it was the military can use 'selective deniability' to
degrade or disabel to civilian signal in a local region.

There are GPS jammers, but their effectiveness is disputed.

Due to the tight control of GPS by the US gov, the Europeans
are develping their own system called GALILEO which will use
the same base frequency (L1) as the NAVSTAR which means most
consumer level GPS units will be compatible. Once this is
available, the idea of the US Gov 'turning off' GPS is moot.

The Russians have GLONASS but it's of limited use.

As for getting rid of VOR training/testing, I think it's silly,
and I don't even have a PPL!!! I know flight sims aren't 100%
accurate but I have no trouble using VOR's in MSFS. Besides,
I think arguing to get rid of VOR training/testing is like
arguing to get rid of parallel parking training/testing in
drivers ed. They've tried making drivers licenses easier to
get and look where it got us. A lot of bad drivers. Now they're
starting to make it tougher again. (too little too late if you
ask me)

Brian
--
http://www.skywise711.com - Lasers, Seismology, Astronomy, Skepticism

Home of the Seismic FAQ
http://www.skywise711.com/SeismicFAQ/SeismicFAQ.html

Sed quis custodiet ipsos Custodes?

I think you just answered your own question, Larry. Them's the same
actions I'd take if I was on top and the VOR went and packed up, so how is a
GPS packing up any different?

Shawn
"Larry Dighera" wrote in message
...
On Thu, 14 Apr 2005 20:48:47 GMT, "Jay Honeck"
wrote in
PGA7e.14356$xL4.13659@attbi_s72::

If, in ten years and nearly 1000 hours of flying, I've never needed to
figure out my position by looking at the face of my VOR, as if I'd
suddenly
awakened in my plane and didn't have a clue where I was, what the hell is
it
doing on the written exam for Private Pilot?

Suppose you are navigating solely by GPS. What are you going to do in
the event the military chooses to disable the GPS system while you're
airborne (or a solar storm renders GPS unusable) and you find yourself
above an undercast? If the aircraft isn't equipped with ADF, and you
haven't been trained to use VOR navigation, you'd have to request a DF
steer from FSS, or if you're located in an area of ATC radar coverage,
vectors.

"Larry Dighera" wrote in message
.. .
On Thu, 14 Apr 2005 20:48:47 GMT, "Jay Honeck"
wrote in
PGA7e.14356$xL4.13659@attbi_s72::

If, in ten years and nearly 1000 hours of flying, I've never needed to
figure out my position by looking at the face of my VOR, as if I'd
suddenly
awakened in my plane and didn't have a clue where I was, what the hell is
it
doing on the written exam for Private Pilot?

Suppose you are navigating solely by GPS. What are you going to do in
the event the military chooses to disable the GPS system while you're
airborne (or a solar storm renders GPS unusable) and you find yourself
above an undercast? If the aircraft isn't equipped with ADF, and you
haven't been trained to use VOR navigation, you'd have to request a DF
steer from FSS, or if you're located in an area of ATC radar coverage,
vectors.

On Fri, 15 Apr 2005 17:07:50 GMT, "ShawnD2112"
wrote in
::

I think you just answered your own question, Larry.

In the Los Angeles area, pilots often fly over the vast Mojave Desert
enroute to their destinations. My experience has shown that ARTCC
radar coverage is limited below 8,000' over the Mojave, so radar
vectors may not be available. I have no idea of the coverage provided
by FSS for DF help.

Them's the same
actions I'd take if I was on top and the VOR went and packed up,

You wouldn't just fish your handheld GPS receiver out of your flight
bag, and continue on?

so how is a GPS packing up any different?

If you are an airman trained in VOR navigation, you don't need to rely
on radar nor DF for backup navigation while finding your way with GPS.

Jay Honeck wrote:

You figured out your position using VORs? What decade was this? ;-)

Can I do that? Sure. Can I name the last time I needed to know that?
Nope. Can I even name the last time I did it? Nope.

If, in ten years and nearly 1000 hours of flying, I've never needed to
figure out my position by looking at the face of my VOR, as if I'd suddenly
awakened in my plane and didn't have a clue where I was, what the hell is it
doing on the written exam for Private Pilot? Who in the world uses VORs
for daily flight anymore?

Well, hell, who uses pilotage anymore? Hasn't everybody got a GPS these days?
Why should anyone be required to learn any form of navigation that isn't
state-of-the-art?

/sarcasm

What will you do when that black box fails? I want to be able to use *any*
navigational equipment that happens to be in the plane I'm flying, and *you'd*
better be able to also ('cause I don't want you running into me while you're
trying to remember how it works).

When they disable the VOR network, *then* they should take all the questions
about it off the exams, but not until then.

George Patterson
There's plenty of room for all of God's creatures. Right next to the
mashed potatoes.

What will you do when that black box fails? I want to be able to use *any*
navigational equipment that happens to be in the plane I'm flying, and
*you'd* better be able to also ('cause I don't want you running into me
while you're trying to remember how it works).

When they disable the VOR network, *then* they should take all the
questions about it off the exams, but not until then.

I didn't say anything about not training pilots to use VORs, nor did I say
to take all VOR questions off the test.

I was referring specifically to the pages and pages (ad nauseum) of study
questions that show you a VOR instrument, totally out of context with
anything else, and ask you to determine where you are in relation to the
transmitter.

First of all, if I'm flying along and the "black box" goes dead, I've been
following my position on my sectional -- so I have a pretty good idea where
I am from the get-go. It's not like I'm going to turn on my VOR with NO
knowledge of where I am. I will know approximately where I am in relation
to the transmitter before I even turn it on (after all -- I will need my
sectional to even determine which VOR frequency to tune in -- duh), and will
thus be able to easily and quickly determine my position from/to it. From
that point on, reading a VOR needle is child's play.

The point is, get stupid "gotcha!" questions like these off the written
test. They are put there to confuse and eliminate candidates, nothing
more, nothing less -- and the knowledge they purport to "test" isn't even
represented well by the questions.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:

I was referring specifically to the pages and pages (ad nauseum) of study
questions that show you a VOR instrument, totally out of context with
anything else, and ask you to determine where you are in relation to the
transmitter.

The point is, get stupid "gotcha!" questions like these off the written
test.

It's been a long time since I studied for the PPC written, but I don't recall a
single navigation question that was a "gotcha." Every single one had one
obviously correct answer that was obviously correct if you had any idea how the
things worked. Now, I took my written just before my 300 mile cross-country, so
I had been using a VOR for some time. If you found them to be "gotchas", I'd say
you didn't really have a handle on VOR navigation at the time.

As far as there being pages of study questions, that's simply because there are
ten study questions for every one that gets selected for the exam you take, and
all of those ten are basically the same. If you could've handled one, you
could've answered any of them.

George Patterson
There's plenty of room for all of God's creatures. Right next to the
mashed potatoes.

It's been a long time since I studied for the PPC written, but I don't
recall a single navigation question that was a "gotcha." Every single one
had one obviously correct answer that was obviously correct if you had any
idea how the things worked. Now, I took my written just before my 300 mile
cross-country, so I had been using a VOR for some time. If you found them
to be "gotchas", I'd say you didn't really have a handle on VOR navigation
at the time.

As I said, I scored in the upper 90s, some ten years ago, and have no
trouble using VORs. But they *did* take a significant amount of time to get
proficient at using, and I hope that I'm the last generation of pilots to
have to rely on such an antiquated system for primary navigation.

Since nowadays VFR pilots have little use for VORs, (I don't turn them on --
ever -- except for the occasional practice VOR approach), to put those kind
of questions on the Private written exam is just another way to weed out
potential pilots.

I wonder if VOR tracking is tested in the new Sport Pilot curriculum?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"