GNS430 on the Airway

wrote in message news:3kFHf.38391$JT.30351@fed1read06...
ted wrote:
wrote in message
news:%_hHf.33984$JT.6861@fed1read06...

Matt Barrow wrote:


wrote in message
news:Z_4Hf.33790$JT.747@fed1read06...


Matt Barrow wrote:


How so?




There isn't a newer version because the FAA does not like to admit when
they do incorrect planning.

If those old documents were valid some VORs would already be shutdown.


Though VORs have some use in the near term, I can't see them being
viable beyond a "few" years.




No matter how old or crummy VORs are compared to GPS, GPS still has a
continuity and integrity issue for sole-means en route navigation in a
non-radar domestic airspace environment.


WAAS solves the integrity issue. I'm not sure what you mean by
"continuity issue"



Continuity means the reliability of the primary GPS sats themselves. They
can have a sat failure or, more likely, jamming.

Ground based navaids can fail, can experience jamming (both intentional and
unintentional) and are much more vulnerable to terrain obscuration than
navaids in the sky. I'm not aware of any significant continuity issue for
GPS that are a bigger problem than what is experienced with ground based
navaids.

"Jim Carter" wrote in message
. com...


-----Original Message-----
From: ]
Posted At: Sunday, February 12, 2006 5:53 AM
Posted To: rec.aviation.ifr
Conversation: GNS430 on the Airway
Subject: GNS430 on the Airway

ted wrote:
wrote in message
news:%_hHf.33984$JT.6861@fed1read06...
...clipped for brevity...
[Jim Carter]
Continuity means the reliability of the primary GPS sats themselves.
They can have a sat failure or, more likely, jamming.

[Jim Carter]
Unless control of the satellite management system can be achieved, and
the entire constellation interrupted, wouldn't jamming be a localized
event based on the radiation pattern and power of the jamming
transmitter? And to continue jamming wouldn't the transmitter have to
stay active, making it a pretty easy target for any of several modern
weapons systems that don't rely on GPS for navigation?


I hope you are only referring to intentional jmmers. :-)

Jim Carter wrote:


[Jim Carter]
Unless control of the satellite management system can be achieved, and
the entire constellation interrupted, wouldn't jamming be a localized
event based on the radiation pattern and power of the jamming
transmitter? And to continue jamming wouldn't the transmitter have to
stay active, making it a pretty easy target for any of several modern
weapons systems that don't rely on GPS for navigation?


Jamming is indeed localized, but it can cover a fairly large area for
aircraft operating at high altitude. The jamming that occurs in this
country thus far is "friendly fire."

If hostile forces chose to jam within this country using a mobile
platform, they would be tough to find and destroy. That is why there is
so much jamming today as certain folks try to figure out how to defeat
enemy jamming.

ted wrote:


Ground based navaids can fail, can experience jamming (both intentional and
unintentional) and are much more vulnerable to terrain obscuration than
navaids in the sky. I'm not aware of any significant continuity issue for
GPS that are a bigger problem than what is experienced with ground based
navaids.


Those involved in planning see it differently. That is why the new RNAV
(RNP) criteria presumes a failure of GPS during a terrain-critical phase
of flight.

A long history of FAA ground-based nav aids has shown very, very little
problem with the ground components of the system. And, where it occurs
there is usually an alternate nav aid or aids available.

Terrain obscuration is irrelavant for IFR procedures because of design
and flight inspection confirmation.

wrote
ted wrote:
wrote in message
Matt Barrow wrote:
wrote in message
Matt Barrow wrote:

How so?

There isn't a newer version because the FAA does not like to admit when
they do incorrect planning.

If those old documents were valid some VORs would already be shutdown.

Though VORs have some use in the near term, I can't see them being
viable beyond a "few" years.

No matter how old or crummy VORs are compared to GPS, GPS still has a
continuity and integrity issue for sole-means en route navigation in a
non-radar domestic airspace environment.

WAAS solves the integrity issue. I'm not sure what you mean by
"continuity issue"

Continuity means the reliability of the primary GPS sats themselves. They
can have a sat failure or, more likely, jamming.

Ground based navaids can fail, can experience jamming (both intentional and
unintentional) and are much more vulnerable to terrain obscuration than
navaids in the sky. I'm not aware of any significant continuity issue for
GPS that are a bigger problem than what is experienced with ground based
navaids.

wrote in message...

Those involved in planning see it differently. That is why the new RNAV
(RNP) criteria presumes a failure of GPS during a terrain-critical phase
of flight.

Is that because of the physics and architecture of the GPS/WAAS system or is
it because the system is still new and not yet proven through enough testing
and actual flight experience?


A long history of FAA ground-based nav aids has shown very, very little
problem with the ground components of the system. And, where it occurs
there is usually an alternate nav aid or aids available.

It seems you missed the point. The original point was that the chance of a
failure of GPS is not a rationale for preferring ground based navaids
because ground based navaids can fail as well. No one said or implied that
ground based navaids have a high probability of failure.


Terrain obscuration is irrelavant for IFR procedures because of design and
flight inspection confirmation.

I hope you meant to say that terrain obscuration is irrelevant to the USE of
IFR procedures but it is indeed very relevant to the DESIGN of IFR
procedures. Perhaps we should say "nominal use of IFR procedures" because
there is an inherent assumption that the pilot is following those
procedures properly. Are there any cases of a pilot being off course or
below the proper elevation and thus lost the signal to a navaid due to
terrain obscuration causing additional cockpit confusion that eventually led
to an accident? How many times has an aircraft needed to abort the landing
because another aircraft on the ground blocked the glide slope or localizer
signal from the ground based antenna near the runway? GPS with much greater
coverage from the sky provides more service in more places for those "off
nominal" flight situations.

"Jim Carter" wrote in message
. com...


-----Original Message-----
From: ]
Posted At: Sunday, February 12, 2006 5:53 AM
Posted To: rec.aviation.ifr
Conversation: GNS430 on the Airway
Subject: GNS430 on the Airway

ted wrote:
wrote in message
news:%_hHf.33984$JT.6861@fed1read06...
...clipped for brevity...
[Jim Carter]
Continuity means the reliability of the primary GPS sats themselves.
They can have a sat failure or, more likely, jamming.

[Jim Carter]
Unless control of the satellite management system can be achieved, and
the entire constellation interrupted, wouldn't jamming be a localized
event based on the radiation pattern and power of the jamming
transmitter? And to continue jamming wouldn't the transmitter have to
stay active, making it a pretty easy target for any of several modern
weapons systems that don't rely on GPS for navigation?


http://www.fas.org/man/dod-101/sys/smart/agm-88.htm

http://www.vectorsite.net/twbomb8.html

HARM Block 3a and 5 software updates have completed testing and were
incorporated as a software only engineering change starting in August 1999.
The software improves missile performance against several threat
countermeasures...

The Advanced Anti-Radiation Guided Missile (AARGM) project is adding to the
Block VI capability by demonstrating technology for RF homing integration
with an active millimeter wave terminal seeker to provide a counter-shutdown
capability. Fielding this capability could be in the 2005 timeframe.

http://www.military-aerospace-techno....cfm?DocID=685

http://www.chips.navy.mil/archives/0..._files/GPS.htm

http://www.aeronautics.ru/news/news001/gpsnews001.htm

http://www.afa.org/magazine/May2003/0503road.asp
Threat to GPS Fizzled

The Great GPS Scare turned out to be a false alarm.

In the run-up to the war, some had expressed concern that Iraqi forces could
employ inexpensive jammers to disrupt the relatively weak signal emitted by
Global Positioning System satellites circling the Earth. Disruption of this
nature would have put a severe kink in USAF's ability to use GPS-guided
weapons and navigate in the desert.

However, the problem proved to be largely unfounded, as coalition forces
used GPS-guided weapons with impunity. DOD data shows that coalition forces
by April 5 had dropped more than 3,000 Joint Direct Attack Munitions, just
one type of GPS-guided weapon.

Early in the conflict, there were reports that Iraq had obtained several GPS
jammers, possibly from a Russian supplier. Maj. Gen. Victor E. Renuart Jr.,
Central Command operations director, announced March 25 that coalition
forces had identified six of these jammers and had destroyed all six.

Ted wrote:


Those involved in planning see it differently. That is why the new RNAV
(RNP) criteria presumes a failure of GPS during a terrain-critical phase
of flight.


Is that because of the physics and architecture of the GPS/WAAS system or is
it because the system is still new and not yet proven through enough testing
and actual flight experience?

It's because the known failure rate is considerably higher than with
either VOR or ILS.


A long history of FAA ground-based nav aids has shown very, very little
problem with the ground components of the system. And, where it occurs
there is usually an alternate nav aid or aids available.


It seems you missed the point. The original point was that the chance of a
failure of GPS is not a rationale for preferring ground based navaids
because ground based navaids can fail as well. No one said or implied that
ground based navaids have a high probability of failure.

If I missed the point then you didn't do a very good job of making that
point. I in no way stated a preference for VOR over GPS. All high end
users are using GPS instead of VOR, but most of them have an RNAV backup
to GPS (IRUs) and they are still equipped to revert to VOR/DME because
they are required to be so equipped by the FAA.


Terrain obscuration is irrelavant for IFR procedures because of design and
flight inspection confirmation.


I hope you meant to say that terrain obscuration is irrelevant to the USE of
IFR procedures but it is indeed very relevant to the DESIGN of IFR
procedures.

Note the "because of..." in my previous statement.



Perhaps we should say "nominal use of IFR procedures" because
there is an inherent assumption that the pilot is following those
procedures properly. Are there any cases of a pilot being off course or
below the proper elevation and thus lost the signal to a navaid due to
terrain obscuration causing additional cockpit confusion that eventually led
to an accident?

No doubt there have been accidents because of errant blunders. Same
goes for GPS. You can lead a horse to water but.....

How many times has an aircraft needed to abort the landing
because another aircraft on the ground blocked the glide slope or localizer
signal from the ground based antenna near the runway? GPS with much greater
coverage from the sky provides more service in more places for those "off
nominal" flight situations.

At Class D airports the blockage of ILS during adverse weather
conditions is very unusual. At non-tower airports it does occur, but
whether at any greater rate than someone blocking the runway causing a
missed approach on a VOR IAP or GPS IAP is unknown. The risks inherent
with IFR operations at non-towered airports is certainly greater than at
towered airports.

ILS will continue to be the primary approach and landing aid for many
years and for many reasons, including the fact that RNP procedures have
a long way to go before they can provide the precision of ILS within a
mile, or so, of the runway threshold. LPV is worse. This becomes
significant for air carrier all-weather ops in particular; i.e., CAT III
autoland operations.

VOR will continue to be primary for *en route* for some unknown and
unplanned period of time, which was my premise about VOR from the
beginning of this thread. VOR has always been a lousy approach aid.

wrote in message news:Sf0If.38585$JT.12812@fed1read06...
Ted wrote:


Those involved in planning see it differently. That is why the new RNAV
(RNP) criteria presumes a failure of GPS during a terrain-critical phase
of flight.


Is that because of the physics and architecture of the GPS/WAAS system or
is it because the system is still new and not yet proven through enough
testing and actual flight experience?

It's because the known failure rate is considerably higher than with
either VOR or ILS.

Really? Where did you get that data? Show us your source.




A long history of FAA ground-based nav aids has shown very, very little
problem with the ground components of the system. And, where it occurs
there is usually an alternate nav aid or aids available.


It seems you missed the point. The original point was that the chance of
a failure of GPS is not a rationale for preferring ground based navaids
because ground based navaids can fail as well. No one said or implied
that ground based navaids have a high probability of failure.

If I missed the point then you didn't do a very good job of making that
point.

Sorry, my intended audience was people who could read english.


I in no way stated a preference for VOR over GPS.

Oh really? Then what did you mean when you said this?:

wrote:
No matter how old or crummy VORs are compared to GPS, GPS still has a
continuity and integrity issue for sole-means en route navigation in a
non-radar domestic airspace environment.

The point you seem unable to follow is that GPS, when fully certified, has
no more continuity or integrity issues than VORs do.

ted wrote:


Sorry, my intended audience was people who could read english.

I thought we were having a reasonable technical discussion. Instead,
you are another Usenet droid asshole.

wrote in message news:5I9If.38637$JT.20875@fed1read06...
ted wrote:


Sorry, my intended audience was people who could read english.

I thought we were having a reasonable technical discussion. Instead, you
are another Usenet droid asshole.

That's rich...coming from the original Usenet droid asshole/****house
lawyer.