distance u03b2 g m from the scan lines in the first field recall that u03b4 depends on the velocity of the aircraft to determine the velocity v and angle u03b8 which are solutions yielding m lines equally spaced the following equation must be solved equ25 the velocity v and the angle u03b8 that satisfy this equation provide solutions having m scan lines equally spaced except for the case when u03b8 u03b1 this corresponds to the scan lines being parallel to the direction of flight and u03b4 u221e in any case it is important to maintain m overlapping fields to prevent gaps in the data the sensitivity of u03b4 to variations of the angle u03b8 is determined by using percentage sensitivity a percentage sensitivity to small variations is attained by dividing a first derivative of a function by the function itself in this connection it is desirable to have small values of the percentage sensitivity in the following analysis u03b4 is the function whose sensitivity is to be determined with respect to variations in the angle u03b8 a u03b8 below is the equation within the absolute value of the numerator of u03b4 and c gy is the denominator of u03b4 in other words equ26 where the equations for a u03b8 and c gy are equ27 from these equation the first derivative can be obtained with respect to the angle u03b8 equ28 the graph of this function using the typical values used for the previous sensitivity analysis and with the x axis representing values of the angle u03b8 measured in radians is shown in fig9 from fig9 it is apparent that u03b4 is extremely sensitive to variations of the angle u03b8 for values of the angle u03b8 near.