  A method to quantify the probabilistic controller taskload inherent to
maintaining aircraft adherence to 4-D trajectories within flow corridors is
presented. An Ornstein-Uhlenbeck model of the aircraft motion and a Poisson
model of the flow scheduling are introduced along with reasonable numerical
values of the model parameters. Analytic expressions are derived for the
taskload probability density functions for basic functional elements of the
flow structure. Monte Carlo simulations are performed for these basic
functional elements and the controller taskload probabilities are exhibited.
