6 ms·

Can someone provide context?

a-no-n 10y ago
There was a cancelled, very large proposed GPS outage (NOTAM) centered on NAWS China Lake which specifically warned that the EMB-505 Phenom 300 business jet specifically should avoid operating in the Western US during this mysterious GPS outage/jamming test event.[0] Pressure from the AOPA and others likely contributed to the scrubbing of this would-be very large outage.[1] It turns out that the EMB-505 300 lateral stability at high speed is extremely dependent on GPS. Folks on the forums suspect the root cause is related to the Garmin GRS 77/GMU 44 AHRS part of the Garmin Prodigy G3000 package.[2,3] 0. https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_GPS_Flight_Advisory.pdf https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_... 1. http://www.ainonline.com/aviation-news/business-aviation/2016-06-10/aopa-military-scrubs-planned-gps-interference-testing http://www.ainonline.com/aviation-news/business-aviation/201... 2. http://static.garmin.com/pumac/778_InstallationManual.pdf http://static.garmin.com/pumac/778_InstallationManual.pdf 3. http://static.garmin.com/pumac/1152_GRS77_GMU44TroubleshootingReference.pdf http://static.garmin.com/pumac/1152_GRS77_GMU44Troubleshooti...
- kaffeemitsahne 10y ago
  What would be the purpose of this outage?
  - colechristensen 10y ago
    "China Lake is the United States Navy's largest single landholding, representing 85 percent of the Navy’s land for weapons and armaments research, development, acquisition, testing and evaluation (RDAT&E) use and 38 percent of the Navy’s land holdings worldwide. In total, its two ranges and main site cover more than 1,100,000 acres (4,500 km2), an area larger than the state of Rhode Island."
  - deleted 10y ago
    [deleted]
  - chiph 10y ago
    Possibly to ensure that weapons and weapon systems that use GPS will still function in it's absence.
  - jonknee 10y ago
    It's classified, but they may have been testing GPS jamming equipment or other rf tech that has that as a side effect.
JshWright 10y ago
It appears that the Embraer Phenom 300 has GPS so deeply integrated into its "flight control computer" that the loss of GPS results in the loss of a number of important systems, including the system that prevents a common aerodynamic instability, known as "Dutch Roll". Modern planes aren't flown directly by people. They're flown by computers, with people using the controls in the cockpit to tell the computer what they want the plane to do (there is no direct link between the stick/yoke and the flight surfaces). The computer integrates all the information at its disposal and determines what movements of the flight control systems are necessary to meet the pilot's commands (this is known as fly by wire). In this case, it seems that computer is _really_ dependant on GPS.
- jsmthrowaway 10y ago
  > (there is no direct link between the stick/yoke and the flight surfaces) Almost true and oft-repeated. There are still means to somewhat control most FBW aircraft in the unlikely event all electrical control is lost; A320 can pitch/yaw with mechanical linkage to stabilizer trim and the rudder, for example (but, to your point, neither involve the sidestick). The flight is very likely headed for an unpleasant end but the intent is to buy time to restore computer control. Landing with trim, rudder, and differential thrust alone is possible (some have landed with less), but it's a big ask for a pilot accustomed to automation. That scenario aside, when a whole lot of things fail an Airbus can also go into a mode called Direct Law, which basically tells the computer to take a hike and puts the pilot in direct control of surfaces proportional to airspeed (and puts structural integrity in jeopardy, because the computer isn't helping to obey design limits). The aircraft is extremely sensitive in this configuration. (If you saw Sully recently, one of the reasons he quickly started the APU was to prevent the aircraft from leaving the relative safety of Normal Law in the absence of electrical power. This was described in the report, if I recall, and was one of the more critical decisions made.) Boeing is entirely different in FBW philosophy from Airbus. A coarse summary might be that Airbus drivers are negotiating with a computer while Boeing drivers are generally flying the airplane. Both have merits and drawbacks and vocal camps.
  - JshWright 10y ago

There was a cancelled, very large proposed GPS outage (NOTAM) centered on NAWS China Lake which specifically warned that the EMB-505 Phenom 300 business jet specifically should avoid operating in the Western US during this mysterious GPS outage/jamming test event.[0] Pressure from the AOPA and others likely contributed to the scrubbing of this would-be very large outage.[1] It turns out that the EMB-505 300 lateral stability at high speed is extremely dependent on GPS. Folks on the forums suspect the root cause is related to the Garmin GRS 77/GMU 44 AHRS part of the Garmin Prodigy G3000 package.[2,3] 0. https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_GPS_Flight_Advisory.pdf https://www.faasafety.gov/files/notices/2016/Jun/CHLK_16-08_... 1. http://www.ainonline.com/aviation-news/business-aviation/2016-06-10/aopa-military-scrubs-planned-gps-interference-testing http://www.ainonline.com/aviation-news/business-aviation/201... 2. http://static.garmin.com/pumac/778_InstallationManual.pdf http://static.garmin.com/pumac/778_InstallationManual.pdf 3. http://static.garmin.com/pumac/1152_GRS77_GMU44TroubleshootingReference.pdf http://static.garmin.com/pumac/1152_GRS77_GMU44Troubleshooti...

kaffeemitsahne 10y ago
What would be the purpose of this outage?
- colechristensen 10y ago
  "China Lake is the United States Navy's largest single landholding, representing 85 percent of the Navy’s land for weapons and armaments research, development, acquisition, testing and evaluation (RDAT&E) use and 38 percent of the Navy’s land holdings worldwide. In total, its two ranges and main site cover more than 1,100,000 acres (4,500 km2), an area larger than the state of Rhode Island."
- deleted 10y ago
  [deleted]
- chiph 10y ago
  Possibly to ensure that weapons and weapon systems that use GPS will still function in it's absence.
- jonknee 10y ago
  It's classified, but they may have been testing GPS jamming equipment or other rf tech that has that as a side effect.

JshWright 10y ago

It appears that the Embraer Phenom 300 has GPS so deeply integrated into its "flight control computer" that the loss of GPS results in the loss of a number of important systems, including the system that prevents a common aerodynamic instability, known as "Dutch Roll". Modern planes aren't flown directly by people. They're flown by computers, with people using the controls in the cockpit to tell the computer what they want the plane to do (there is no direct link between the stick/yoke and the flight surfaces). The computer integrates all the information at its disposal and determines what movements of the flight control systems are necessary to meet the pilot's commands (this is known as fly by wire). In this case, it seems that computer is _really_ dependant on GPS.

jsmthrowaway 10y ago
> (there is no direct link between the stick/yoke and the flight surfaces) Almost true and oft-repeated. There are still means to somewhat control most FBW aircraft in the unlikely event all electrical control is lost; A320 can pitch/yaw with mechanical linkage to stabilizer trim and the rudder, for example (but, to your point, neither involve the sidestick). The flight is very likely headed for an unpleasant end but the intent is to buy time to restore computer control. Landing with trim, rudder, and differential thrust alone is possible (some have landed with less), but it's a big ask for a pilot accustomed to automation. That scenario aside, when a whole lot of things fail an Airbus can also go into a mode called Direct Law, which basically tells the computer to take a hike and puts the pilot in direct control of surfaces proportional to airspeed (and puts structural integrity in jeopardy, because the computer isn't helping to obey design limits). The aircraft is extremely sensitive in this configuration. (If you saw Sully recently, one of the reasons he quickly started the APU was to prevent the aircraft from leaving the relative safety of Normal Law in the absence of electrical power. This was described in the report, if I recall, and was one of the more critical decisions made.) Boeing is entirely different in FBW philosophy from Airbus. A coarse summary might be that Airbus drivers are negotiating with a computer while Boeing drivers are generally flying the airplane. Both have merits and drawbacks and vocal camps.
- JshWright 10y ago