 PIGA accelerometers mounted in the AIRS (Advanced Inertial Reference Sphere) are part of most accurate inertial navigation (INS) developed for the MX Missile.The INS drift rates are less than 1.5 x 10−5 degrees per hour of operation, about 8.5m per hour with the overall accuracy of the missile affected more by defects in the gravitational maps.A recovered MMIA accelerometer from an unexploded V2 was presented to Dr Charles Stark Draper of the United States's MIT instrumentation lab who had been developing the basis of inertial navigation for aircraft by initially concentrating efforts on achieving extremely low drift rate gyroscopes known as a floated integrating gyroscope.