9.A.3.Linear accelerometers, designed for use in inertial navigation systems or in guidance systems of all types, usable in the systems specified in 1.A., 19.A.1. or 19.A.2., having all of the following characteristics, and specially designed components therefor:

a. 'Scale factor' 'repeatability' less (better) than 1250 ppm; and
b. 'Bias' 'repeatability' less (better) than 1250 micro g.
Note:
Item 9.A.3. does not control accelerometers specially designed and developed as Measurement While Drilling (MWD) sensors for use in downhole well service operations.
Technical Notes:
1. 'Bias' is defined as the accelerometer output when no acceleration is applied.
2. 'Scale factor' is defined as the ratio of change in output to a change in the input.
3. The measurement of 'bias' and 'scale factor' refers to one sigma standard deviation with respect to a fixed calibration over a period of one year.
4. 'Repeatability' is defined according to IEEE Standard for Inertial Sensor Terminology 528-2001 in the Definitions section paragraph 2.214 titled repeatability (gyro, accelerometer) as follows: 'The closeness of agreement among repeated measurements of the same variable under the same operating conditions when changes in conditions or non-operating periods occur between measurements'.