Number 257
January 2001
Experiences with GPS
The Global Positioning System (GPS) is a worldwide, satellite-based radio navigation system that is based on several components — ground stations that control the system; a “constellation” of 24 or more satellites orbiting 11,000 miles above the surface of the earth; and receivers carried by users. GPS signals are derived from the atomic frequency standards on board each satellite. When receiving the signals from at least 4 satellites, a ground-based receiver can determine latitude, longitude, altitude, and time – highly accurate information used by both air carrier and general aviation pilots. But GPS use also requires judicious cross-checking with cockpit charts and instruments, as well as knowledge of the technology’s limitations. Several ASRS reports explain:
opstr
jsuw gtye
iw
carrier flights transitioning to or from the airport terminal area. Safer practice is to maintain an appropriate VFR altitude buffer between the aircraft and Class B floor/ceiling altitudes.
s I was enroute and intended to utilize the GPS approach.
After loading the approach into my IFR-certified GPS [unit], I decided to head direct to the XYZ GPS fix. I thought that the XYZ fix was the same as the XYZ airport. Unfortunately, the fix was slightly northwest of the airport. My path took me directly over a Restricted Area. Since I was descending for the GPS approach I possibly broke the 2999 foot MSL ceiling of the Restricted Area. ASRS frequently hears from pilots who “go direct” with GPS and neglect other flight planning. A quick look at a VFR chart, low altitude IFR chart, or the airport GPS approach plate would have helped this pilot differentiate between the location of the GPS fix and the airport location. The use of flight following, even with no flight plan filed, might also have prevented the airspace violation.
Code/A Alert
Another pilot reported that he used GPS successfully to navigate to a distant point on an IFR flight plan – but ran afoul of the FARs in the process:
Confused by the Map
Our next reporter relied on a visual feature of GPS for navigation when other features would have better served the purpose:
s IFR flight plan filed on airways [with] equipment Code/A. Aircraft equipped with 2 VFR GPS units, with current database. Requested and received vectors (radar) for a short-cut on the route. Controller asked if I had GPS. I replied “VFR” GPS. Used GPS to aid navigation to vector fix. When handed over to next Center controller, he rerouted my flight plan and current radar vector to a quite distant VOR fix. All was going well until we were handed over to Approach, who complained that we were filed equipment /A but were flying to a distant fix on GPS navigation. He said I should have refused the unsolicited rerouting by Center. I remain confused, as it’s my understanding that using any GPS as an adjunct to flying an assigned radar vector to a fix is legal. Nothing dangerous occurred. Conditions CAVU, VMC, continuous radar contact.
IFR equipment rules apply to all conditions under which instrument flights may be made, including CAVU. According to Section 5-1-7(a)3 of the current Aeronautical Information Manual, the /A notation on an IFR flight plan indicates that the aircraft has transponder with Mode C capability only. The /G notation indicates that the aircraft is GPS/GNSS equipped with enroute, terminal, and approach GPS capability. The reporter erred twice — in requesting a route short-cut using VFR-certified GPS on an IFR flight plan; and in accepting the Center controller’s reroute to the distant fix. The Center controller in this case should not have approved the direct reroute, since the pilot legally should have had IFR-certified GPS on board in case radar coverage was lost.
s Took off from field, relied on GPS moving map for
Class G guidance. Too many lines on screen and I interpreted [them] to mean I was under Class B segment with base at 3,000 feet. At 2,200 feet Tower informed me I should be at 1,700 feet. Flew east at 1,700 feet until clear, then back up to 3,000 feet under Class B airspace. Should not have relied on moving map. Should have calculated Class B transition points with GPS or VOR/DME. An additional factor past ASRS research has demonstrated leads to Class B airspace violations is flying too close to the floor (or ceiling) of Class B airspace. ATC often uses the floor/ceiling altitudes to route IFR air
ASRS Recently Issued Alerts On…
B757-200 power port converter electrical short Multiple reports of ATC incidents at a major NY airport A319 pitch-up on approach with engines in auto throttle Laptop computer interference with B767 cabin speakers Bulb replacement anomaly involving a SF340A gear light
A Monthly Safety Bulletin from
The Office of the NASA Aviation Safety Reporting System, P.O. Box 189, Moffett Field, CA 94035-0189 http://asrs.arc.nasa.gov/
November 2000 Report Intake
Air Carrier / Air Taxi Pilots General Aviation Pilots Controllers Cabin/Mechanics/Military/Other TOTAL 2388 662 74 168 3292
飞行翻译公司 www.aviation.cn 本文链接地址：美国ASRS安全公告CALLBACK cb_257.pdf
January 2001
Experiences with GPS
The Global Positioning System (GPS) is a worldwide, satellite-based radio navigation system that is based on several components — ground stations that control the system; a “constellation” of 24 or more satellites orbiting 11,000 miles above the surface of the earth; and receivers carried by users. GPS signals are derived from the atomic frequency standards on board each satellite. When receiving the signals from at least 4 satellites, a ground-based receiver can determine latitude, longitude, altitude, and time – highly accurate information used by both air carrier and general aviation pilots. But GPS use also requires judicious cross-checking with cockpit charts and instruments, as well as knowledge of the technology’s limitations. Several ASRS reports explain:
opstr
jsuw gtye
iw
carrier flights transitioning to or from the airport terminal area. Safer practice is to maintain an appropriate VFR altitude buffer between the aircraft and Class B floor/ceiling altitudes.
s I was enroute and intended to utilize the GPS approach.
After loading the approach into my IFR-certified GPS [unit], I decided to head direct to the XYZ GPS fix. I thought that the XYZ fix was the same as the XYZ airport. Unfortunately, the fix was slightly northwest of the airport. My path took me directly over a Restricted Area. Since I was descending for the GPS approach I possibly broke the 2999 foot MSL ceiling of the Restricted Area. ASRS frequently hears from pilots who “go direct” with GPS and neglect other flight planning. A quick look at a VFR chart, low altitude IFR chart, or the airport GPS approach plate would have helped this pilot differentiate between the location of the GPS fix and the airport location. The use of flight following, even with no flight plan filed, might also have prevented the airspace violation.
Code/A Alert
Another pilot reported that he used GPS successfully to navigate to a distant point on an IFR flight plan – but ran afoul of the FARs in the process:
Confused by the Map
Our next reporter relied on a visual feature of GPS for navigation when other features would have better served the purpose:
s IFR flight plan filed on airways [with] equipment Code/A. Aircraft equipped with 2 VFR GPS units, with current database. Requested and received vectors (radar) for a short-cut on the route. Controller asked if I had GPS. I replied “VFR” GPS. Used GPS to aid navigation to vector fix. When handed over to next Center controller, he rerouted my flight plan and current radar vector to a quite distant VOR fix. All was going well until we were handed over to Approach, who complained that we were filed equipment /A but were flying to a distant fix on GPS navigation. He said I should have refused the unsolicited rerouting by Center. I remain confused, as it’s my understanding that using any GPS as an adjunct to flying an assigned radar vector to a fix is legal. Nothing dangerous occurred. Conditions CAVU, VMC, continuous radar contact.
IFR equipment rules apply to all conditions under which instrument flights may be made, including CAVU. According to Section 5-1-7(a)3 of the current Aeronautical Information Manual, the /A notation on an IFR flight plan indicates that the aircraft has transponder with Mode C capability only. The /G notation indicates that the aircraft is GPS/GNSS equipped with enroute, terminal, and approach GPS capability. The reporter erred twice — in requesting a route short-cut using VFR-certified GPS on an IFR flight plan; and in accepting the Center controller’s reroute to the distant fix. The Center controller in this case should not have approved the direct reroute, since the pilot legally should have had IFR-certified GPS on board in case radar coverage was lost.
s Took off from field, relied on GPS moving map for
Class G guidance. Too many lines on screen and I interpreted [them] to mean I was under Class B segment with base at 3,000 feet. At 2,200 feet Tower informed me I should be at 1,700 feet. Flew east at 1,700 feet until clear, then back up to 3,000 feet under Class B airspace. Should not have relied on moving map. Should have calculated Class B transition points with GPS or VOR/DME. An additional factor past ASRS research has demonstrated leads to Class B airspace violations is flying too close to the floor (or ceiling) of Class B airspace. ATC often uses the floor/ceiling altitudes to route IFR air
ASRS Recently Issued Alerts On…
B757-200 power port converter electrical short Multiple reports of ATC incidents at a major NY airport A319 pitch-up on approach with engines in auto throttle Laptop computer interference with B767 cabin speakers Bulb replacement anomaly involving a SF340A gear light
A Monthly Safety Bulletin from
The Office of the NASA Aviation Safety Reporting System, P.O. Box 189, Moffett Field, CA 94035-0189 http://asrs.arc.nasa.gov/
November 2000 Report Intake
Air Carrier / Air Taxi Pilots General Aviation Pilots Controllers Cabin/Mechanics/Military/Other TOTAL 2388 662 74 168 3292
飞行翻译公司 www.aviation.cn 本文链接地址：美国ASRS安全公告CALLBACK cb_257.pdf
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