Monitoring system for monitoring the environment, in particular of the return space of motor vehicles

The invention relates to a monitoring system for monitoring the environment, in particular of the return space of motor vehicles and trailers with several, in a main plane and in at least arranged an additional level of distance sensors is founded for detecting a risk of collision and / or the drive-through height and / or the passage width limiting objects or obstacles in the each monitoring range (10 ', 12', 14 ') and with a the distance sensor signals evaluating means (30) for determining the current distance (actual value) of the motor vehicle to the detected object or obstruction, and for comparing the actual value with a predeterminable vehicle-specific distance setpoint and outputting a warning signal when it falls below a predetermined difference value between actual and desired values. In order to cover the surveillance area not only in the surface but also in height, additional distance sensors (12, 14) are arranged on the vehicle in at least one additional plane such that objects (20, 22) and obstacles over the entire width of the vehicle can be detected, the by the distance sensors (10) in the main plane (2) can not be detected.