ABSTRACT
High speed low-altitude flight is an advanced form of flight requiring skilled pilots with special training. In its most taxing varieties and moments it demands precision and responsiveness of control almost to the level of prescience. Precision is demanded because a deviation of a few tens of feet from an intended altitude might mean clipping a tree or exposing oneself to an enemy. S. H. Johnson and A. V. Phatak modeled this local control strategy and found close agreement between the model and human performance in their altitude control studies. The performatory demands of low-altitude flight are due to the fast-changing and hazardous spatiotemporal relationship of the pilot and the environment, that is, the dynamic ecology. This environment provides advantages as well as dangers. The focus of optical outflow or the focus of expansion is optically coincident with the point in the environment toward which the observer is heading. The local retinal cue for heading is called differential motion parallax.
