Abstract: A plane dropping leaflets passes through a point and looking sequentially at regions in the plane, the estimation of the direction followed by the plane is desired. This is an example of a non-homogeneous Poisson process and the maximum likelihood estimator can be obtained explicitly when search regions are circles. ln this case, the existence of optimal stopping time, when the cost function is the sum of the cost of sampling plus the cost of estimating error, can be established but numerical results are hard to be obtained. Suboptimal stopping times are proposed Ver menos