typically the aircraft 1 electrical system will provide the electrical power 20 to the system although an internal battery backup not shown may also be included power conditioning is provided as necessary for various system electronic components through dc dc converters not shown as shown in the block diagram two low cost pressure sensors 30 a 30 b are employed one of these sensors 30 a is open to the ambient atmosphere to provide a measure of aircraft barometric altitude the second pressure sensor 30 b is actually a differential sensor sensing the difference between ambient barometric pressure and dynamic pressure provided through a pitot tube thereby providing a measure of airspeed such an instrument may be integrated with the aircraft 39 s existing pitot static system not shown the next sensor is a part of a three axis orthogonal microelectromechanical mems rate gyro array system 40 the primary function of the gyro array system 40 is to sense aircraft roll yaw and pitch rates it should be noted that one single axis gyro mounted near the aircraft 39 s vertical plane at an angle to the vertical and longitudinal axes is sufficient for sensing any combination of roll and yaw motions and represents the minimum sensor set for operation of the system 10 as will be discussed in more detail below a full set of separate orthogonal roll yaw and pitch gyros can be used to provide enhanced heading estimation alternatively a full set of orthogonal accelerometers and at.