не верьте первому посту, здесь правильно
The FAC controls the speed scale on PFD.
When both FACs are operative, FAC1 supplies data to PFD1 and FAC2 supplies it to PFD2.
The principle of speed computation is as follows:
- First, the FAC computes VS1G (stall speed). From VS1G it computes the Gross Weight (GW) which is also sent to the Elevator Aileron computers:
* When the aircraft is below 14500 feet and 250 knots, it computes this from current angle of attack, speed/Mach, altitude, thrust, and CG.
* When the aircraft is above 14500 feet or 250 knots, it computes this out of the GW, which it has memorized and updated whis a fuel consumption model set in the FAC.
- Finally the FAC computes the various minimum and maneuvering speeds, Va prot and Vsw.
- The accuracies of the various minimum and maximum speed are functions of the accuracy with which the FAC computes aircraft gross weight. Normal accuracy for VLS in CONFIG FULL is about 3 kt.
When both FACs are operative, FAC1 supplies data to PFD1 and FAC2 supplies it to PFD2.
The principle of speed computation is as follows:
- First, the FAC computes VS1G (stall speed). From VS1G it computes the Gross Weight (GW) which is also sent to the Elevator Aileron computers:
* When the aircraft is above 14500 feet and 250 knots, it computes this from current angle of attack, speed/Mach, altitude, thrust, and CG.
* When the aircraft is below 14500 feet or 250 knots, it computes this out of the GW, which it has memorized and updated whis a fuel consumption model set in the FAC.
- Finally the FAC computes the various minimum and maneuvering speeds, Va prot and Vsw.
- The accuracies of the various minimum and maximum speed are functions of the accuracy with which the FAC computes aircraft gross weight. Normal accuracy for VLS in CONFIG FULL is about 3 kt.