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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 i

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
  > 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). Yeah, that's why I was specific about the stick/yoke connection. Though, after some research, it appears I was wrong about that as well (as least in the case of Embraer). In the 190, the ailerons are, effectively, directly controlled (there is a hydraulic system in line, but it is directly actuated by cables from the yoke). I was unable to find any conclusive details about the Phenom 300 after a cursory search, but it appears it is "fully" FBW. > 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. Yeah, and both sides can point to major incidents that wouldn't have happened in the other cockpit.
  - throwanem 10y ago
    I know of Air France 447 in the "fly the airplane" camp. (An inexperienced copilot stalled the aircraft all the way from cruise altitude to impact, and because the sidesticks aren't linked, no one else could tell that was what was wrong.) What's a good example in the "negotiate with the computer" camp? Perhaps it's merely a tendency on my part, but I don't think I have run across any accident which militates as strongly in favor of Airbus's design as AF 447 seems to militate against it.
    - rockdoe 10y ago
      AA 587, which ironically happened on an early model Airbus before they went FBW. Your perspective will influence how you classify the accidents. Proponents of full FBW will argue AF 447 happened exactly because part of the FBW system was disabled.
    - pedrocr 10y ago
      >I don't think I have run across any accident which militates as strongly in favor of Airbus's design as AF 447 seems to militate against it. The references I've seen to advantages tend to be more subtle than the AF447 tragedy. Things like the Hudson river landing where in that strange situation where you have no power the workload was diminished by having the computer keep the airplane flying most efficiently and thus be able to reach the river instead of crashing by losing airspeed. It also makes sense the advantages are less obvious as the flight envelope protection actively prohibits dangerous situations and you can't report on non-events. The stats also show Boeing and Airbus airplanes pretty evenly matched on safety.

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
> 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). Yeah, that's why I was specific about the stick/yoke connection. Though, after some research, it appears I was wrong about that as well (as least in the case of Embraer). In the 190, the ailerons are, effectively, directly controlled (there is a hydraulic system in line, but it is directly actuated by cables from the yoke). I was unable to find any conclusive details about the Phenom 300 after a cursory search, but it appears it is "fully" FBW. > 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. Yeah, and both sides can point to major incidents that wouldn't have happened in the other cockpit.
- throwanem 10y ago
  I know of Air France 447 in the "fly the airplane" camp. (An inexperienced copilot stalled the aircraft all the way from cruise altitude to impact, and because the sidesticks aren't linked, no one else could tell that was what was wrong.) What's a good example in the "negotiate with the computer" camp? Perhaps it's merely a tendency on my part, but I don't think I have run across any accident which militates as strongly in favor of Airbus's design as AF 447 seems to militate against it.
  - rockdoe 10y ago
    AA 587, which ironically happened on an early model Airbus before they went FBW. Your perspective will influence how you classify the accidents. Proponents of full FBW will argue AF 447 happened exactly because part of the FBW system was disabled.
  - pedrocr 10y ago
    >I don't think I have run across any accident which militates as strongly in favor of Airbus's design as AF 447 seems to militate against it. The references I've seen to advantages tend to be more subtle than the AF447 tragedy. Things like the Hudson river landing where in that strange situation where you have no power the workload was diminished by having the computer keep the airplane flying most efficiently and thus be able to reach the river instead of crashing by losing airspeed. It also makes sense the advantages are less obvious as the flight envelope protection actively prohibits dangerous situations and you can't report on non-events. The stats also show Boeing and Airbus airplanes pretty evenly matched on safety.