In June of 2001
Houston was conducting normal training operations in the Pacific off the coast of
Washington state, which included a "crash back" drill, in which the ship goes from ahead flank (maximum forward speed) to back full emergency (maximum engine power in reverse). The maneuver proceeded well, despite the tremendous shaking, noise, and stress the maneuver creates, until the boat began to gain sternway (actually moving backwards through the water).
When a vessel is moving backwards, her rudder and in the case of a submarine, her planes, function in the opposite manner than when she is moving forwards. The stern planesman failed to compensate for this phenomenon, and continued to try to trim the boat as if they still were making headway. When the stern began to rise, he raised the stern planes, which would have depressed the stern if they had been moving forward. While making sternway, it had the opposite effect, increasing the down-angle. The stern continued to rise, more rapidly as the boat accelerated backwards. Before the problem could be corrected,
Houston had attained a
70 degree down-angle and her screw broached the surface while still turning at a high rpm. The control team performed a partial emergency ballast tank blow and safely surfaced the boat.