In this chapter, the guidance algorithm is described in the context of the previous sections with necessary details and explanations. For the original description of this algorithm, the reader is referred to Klumpp’s work in Ref. [1]. As mentioned in the previous chapters, the execution time for the P63-64 guidance algorithm is computed in the ignition algorithm. The guidance cycle on BP is repeated every \(Dt=2\) seconds and on AP—every second, while orbital integration is carried out every 1 or less second. It is necessary to distinguish the guidance cycle which is used in the targeting process on the ground and on-board. The results of the guidance cycle in the ground procedures are used iteratively to determine initial, terminal and target states of the braking phase.