The U.S. Navy has developed an electronic system that allows aircraft to practice bombing at sea, and ships to fire at virtual land targets, rather than on land. VAST (Virtual At Sea Trainer) consists of five customized sonobouys that record where shells or bombs hit. Computer software take that data and GPS location info and match it to the virtual land image put onto the radar screens or map displays of gun crews. As far as the gun crews are concerned, they are looking at the same kind of visual information they would have if firing against a real coastal area. The sonobouy data shows how accurate the firing is. For aircraft, the system simulates night bombing, when all the pilot has is electronically collected information for dropping his bomb. In any event, most bombing missions today use GPS bombs, which require precise location information to be entered into the bombs guidance system. Each VAST system costs $50,000 and three were delivered to the Atlantic Fleet in 2002.