This paper describes a control hierarchy to drive a wheelchair using an interface with asynchronous and very low information transfer rate signal. Path guiding assistance allows the user to bring his or her wheelchair in a building environment, from one destination to the next destination. The user can stop the wheelchair voluntarily during movement, or through a reflex elicited by sensors. Decisions are simplified by presenting only the possible selections on the GUI, in a context dependent menu. This system is implemented on a conventional wheelchair with a P300 Brain Machine Interface. Tests with healthy subjects show that this system can move the wheelchair in a typical building environment according to the wishes of its user, and that the brain control is not disturbed by the movement.