A method and apparatus for generating visible objects not blocked by other objects in a simulation during training with aircraft. A position for each aircraft in a number of aircraft is identified for which objects that block the fields of view for each aircraft are to be identified to form a number of positions for the number of aircraft. Any object in the simulation that blocks a portion of a field of view for each aircraft at the position for each aircraft is identified to form a number of objects. Simulation data is created for a number of visible objects not blocked by the number of objects in the simulation that has been identified as blocking the portion of the field of view for each aircraft in the number of aircraft. The simulation data is sent to each aircraft in the number of aircraft.