|This article is about the machine spirit, for the short story by Nick Kyme see Machine Spirit (Short Story)|
A machine spirit is what the Imperium refers to as a vehicle's automatic systems.
The advanced system consists of a combination of organic and mechanical components within the vehicle, and is able to logically control the vehicle's movement and fire its weapons at enemies. Not all vehicles are equipped with such systems, but vehicles that are can operate entirely on their own without a crew, with some success.
The addition of a machine spirit is advantageous in the case of the vehicle's crew being killed or incapacitated, as the auto-systems are able to take control of the vehicle, firing its weapons and driving (providing the systems themselves are still functional). The machine spirit however cannot fully replace the abilities of trained human pilots (going that far might trespass on the Imperium's condemnation of Abominable Intelligences, and could garner the attention of the Inquisition).
A drop pod uses its abilities to handle course corrections and to avoid collisions into dangerous terrain or anti-aircraft fire. Upon landing, it reroutes all logic processing into target acquisition and shooting for any on board weapons.
A Land Raider's machine spirit is capable of virtually taking control of the entire tank for short periods of time, even so far as being able to track multiple targets and engage them simultaneously, or let the tank travel max speed and still unleash heavier weapons than normally permitted. One such famous tale is the Land Raider known as Rynn's Might that belonged to the Crimson Fists Chapter, which survived the missile that leveled their fortress-monastery. Despite not having any crew on board, the machine spirit fought a solo war against an attacking Ork Warband, killing its Warboss and many of his followers overnight, before finally being destroyed.