Median prediction error (t) between the measured flight trajectories and those simulated under the refined mixed guidance law (Equation 1), with best-fitting parameters N=0.75, K=1.25s-1, and tau=0.01s. Because the initial conditions of each simulation were matched to those we had measured, (0)=0 by definition. The simulations deviate from the measured trajectories over time but do so to a greater extent on the n = 154 obstacle test flights (orange) than on the n = 103 obstacle-free test flights (blue). The dashed lines and vertical bars denote the median and interquartile range, respectively, of the times at which the hawks passed the locations of the first and second obstacles. Note that the median prediction error peaks at these times for the test flights with obstacles (orange), but not for the test flights without obstacles (blue), providing evidence of mid-course steering correction to avoid them.
