The path angle, θ, for the uppermost paths should be between 30° and 65° to minimize uncertainties. If the path angle is less, the flow-meter section will be long, and the flow direction may not be constant throughout the section. This would impair the compensating effect of the crossed-path configuration.In trapezoidal channels, if it has been decided to mount the transducers on each bank in sloping arrays normal to the flow direction, the angles for the paths near to the bed should not be less than 30°.