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#51
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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$JT.747@fed1read06... Matt Barrow wrote: How so? There isn't a newer version because the FAA does not like to admit when they do incorrect planning. If those old documents were valid some VORs would already be shutdown. Though VORs have some use in the near term, I can't see them being viable beyond a "few" years. No matter how old or crummy VORs are compared to GPS, GPS still has a continuity and integrity issue for sole-means en route navigation in a non-radar domestic airspace environment. WAAS solves the integrity issue. I'm not sure what you mean by "continuity issue" Continuity means the reliability of the primary GPS sats themselves. They can have a sat failure or, more likely, jamming. Ground based navaids can fail, can experience jamming (both intentional and unintentional) and are much more vulnerable to terrain obscuration than navaids in the sky. I'm not aware of any significant continuity issue for GPS that are a bigger problem than what is experienced with ground based navaids. |
#52
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GNS430 on the Airway
"Jim Carter" wrote in message . com... -----Original Message----- From: ] Posted At: Sunday, February 12, 2006 5:53 AM Posted To: rec.aviation.ifr Conversation: GNS430 on the Airway Subject: GNS430 on the Airway ted wrote: wrote in message news:%_hHf.33984$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. :-) |
#53
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GNS430 on the Airway
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. |
#54
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GNS430 on the Airway
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. |
#55
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GNS430 on the Airway
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. |
#56
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GPS jamming
"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. |
#57
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GNS430 on the Airway
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. |
#58
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GNS430 on the Airway
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. |
#59
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GNS430 on the Airway
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. |
#60
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GNS430 on the Airway
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. |
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