As the craft approached perilune, the descent engine was started again to begin powered descent. During this time, the crew flew on their backs, depending on the computer to slow the craft's forward and vertical velocity to near zero. Control was exercised with a combination of engine throttling and attitude thrusters, guided by the computer with the aid of landing radar. During braking, the LM descended to about , then, in the final approach phase, down to about . During final approach, the vehicle pitched over to a near-vertical position, allowing the crew to look forward and down to see the lunar surface for the first time.